To see the other types of publications on this topic, follow the link: Plant residues in soil.
Dissertations / Theses on the topic 'Plant residues in soil'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Plant residues in soil.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Collins, Shane. "Residue composition influences nutrient release from crop residues." University of Western Australia. School of Earth and Geographical Sciences, 2009. http://theses.library.uwa.edu.au/adt-WU2009.0171.
Full textAbstract:
[Truncated abstract] A greater adoption of stubble retention, minimum-till and no-till farming practices for the purposes of conserving soil, water and fertility requires a greater understanding of the complexity of physical and chemical interactions between the soil and crop residues. There is currently insufficient knowledge to allow reliable predictions of the effects of different residue types in different environments on soil fertility and crop growth, owing to the many residue characteristics and environmental interactions that have been shown to affect decomposition or nutrient release. The role of fibre and nutrient composition in nutrient release from crop residues, and implications for residue management techniques, were studied. Canola, lupin and field pea residues, obtained from farmland in Meckering and Northam, Western Australia, were separated into upper and basal stems, leaves, and siliques or pods. This was done to provide materials with a wide range of chemical and physical characteristics, and also allowed consideration of differential residue management of plant organs, such as comparing harvested canola siliques and retained canola stubble. Pre-treatment by chopping and/or humidification was applied to residues to provide some information about the processes of nutrient release. Residues were subjected to simulated rainfall to assess nutrient leaching from plant material, and placed on soil in pots in constant-temperature glasshouse conditions to assess decomposition. Amounts and rates of change of residue fibre and nutrients were determined throughout leaching and decomposition. Energy Dispersive X-ray (EDX) microanalysis was used to assess the location of diffusible ions in air-dried residues and the effects of humidification on nutrient positioning and release. ... However, the release of calcium and magnesium depended on the decomposition of the more recalcitrant components such as cellulose and lignin, as supported by microscopy results showing changes in nutrient distribution following humidification. The proportionality of amounts of calcium and magnesium leached and released during decomposition is likely to suggest a similarity of chemical form more than similarity of function or position of the two elements. Management of crop residues for maximising and optimising the timing of release of different nutrients will need to take into account the placement of different plant types and parts, particle sizes distribution and pre-treatment of material to efficiently manage short- and long-term soil fertility to sustain crops, particularly on degraded soils. Significant nutrient release of potassium, sulphur and magnesium from crop residues can be achieved from surface placement, with the release of potassium and sulphur managed by modifying residue particle size through appropriate harvesting, ploughing or sowing implement selection. High nutrient uptake crops and plant parts where they can be economically viable to grow or separated by the harvesting technique are particularly valuable as sources of nutrients and soil organic matter.
2
Sakala, Godfrey Mekelani. "The effects of incorporating plant residues on soil acidity in management of tropical soils." Thesis, University of Reading, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.263047.
Full text
3
Ehaliotis, Constantinos. "Nitrogen turnover during decomposition of recalcitrant plant residues in acid soils." Thesis, Imperial College London, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.243408.
Full text
4
Mehdi, Bano B. "Soil nitrate-N and plant nitrogen distributions under different tillage practices." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0005/MQ44220.pdf.
Full text
5
Read, Nicholas A. "Plant Residues and Newspaper Mulch Effects on Weed Emergence And Collard Performance." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1357076611.
Full text
6
White, Paul Mark Jr. "Enhancing soil carbon sequestration with plant residue quality and soil management." Diss., Manhattan, Kan. : Kansas State University, 2006. http://hdl.handle.net/2097/222.
Full text
7
Wei, Xi. "Effects of residual veterinary antibiotics on soil enzyme activity and plant growth." HKBU Institutional Repository, 2007. http://repository.hkbu.edu.hk/etd_ra/830.
Full text
8
Si, Weiduo. "The effect of plant residue decomposition on microbial community composition in soil." Thesis, University of Newcastle Upon Tyne, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.324866.
Full text
9
Amin, Bilal Ahmad Zafar. "Rôle des enzymes lignocellulolytiques dans le processus de biodégradation de résidus végétaux dans les sols : Influence de la qualité des résidus sur l’efficacité des enzymes et leur dynamique." Thesis, Reims, 2012. http://www.theses.fr/2012REIMS029/document.
Full textAbstract:
La décomposition des résidus végétaux joue un rôle essentiel dans le cycle biogéochimique des éléments nutritifs et influence le fonctionnement des écosystèmes. La composition biochimique intrinsèque des résidus végétaux est un facteur clé qui influe sur les processus de décomposition dans le sol tandis que la majorité des réactions biochimiques dans le sol, liées à la biodégradation des résidus végétaux, sont catalysées par des enzymes extracellulaires produites par les microorganismes. L'objectif global de cette étude était d'acquérir des connaissances fondamentales concernant l'impact de la qualité des résidus sur les fonctions microbiennes du sol et les modes d'intervention des enzymes du sol interviennent dans la décomposition des résidus végétaux. Cet objectif a été atteint en trois parties visant à : 1) déterminer le rôle des communautés initiales des résidus i.e. les microorganismes et leurs enzymes provenant des compartiments épiphytes et endophytes, et l'effet de la qualité des résidus végétaux sur les cinétiques des enzymes extracellulaires au cours du processus de décomposition dans le sol 2) étudier l'effet des fonctions microbiennes du sol (biomasse microbienne et enzymes extracellulaires) liées à la minéralisation sur la décomposition ultérieure de résidus introduits dans le même sol 3) explorer les interactions entre la disponibilité en azote et la décomposition des composés phénoliques par l'action des activités oxydo-réductases, et développer une méthode pour mesurer ces activités dans des sols contrastés en utilisant un seul substrat. L'approche générale de cette étude a été de sélectionner les résidus végétaux de qualité chimique variable pour obtenir des cinétiques contrastées de minéralisation du C. Le maïs (Zea mays L.) a été choisi comme plante modèle en raison de variations chimiques et structurales (Mexxal, F2, F2bm1, F292bm3) des parties aériennes (feuilles, entre-nœuds) et souterraines (racines). Des tiges de lin marqué au 13C ont été utilisées pour quantifier avec précision la minéralisation du carbone dans les différents réservoirs de carbone. Afin d'évaluer les relations entre la qualité des résidus végétaux et les fonctions biologiques associées au sol, des expériences en microcosmes contrôlés ont été réalisées en utilisant des sols agricoles et forestiers. La minéralisation du carbone, les caractéristiques chimiques des résidus (teneurs en C et N, les sucres totaux et lignine), la biomasse microbienne et les activités enzymatiques (L-leucine aminopeptidase (LAP), cellobiohydrolase (CBH-1), xylanase, cellulase et la laccase) ont été déterminées à différents stades de décomposition. Les résultats de la première étude ont indiqué que les activités de micro-organismes épiphytes et endogènes étaient du même ordre de grandeur dans le cas des racines, tandis que les activités des enzymes spécifiques (cellulase, xylanase et laccase) étaient fortement corrélées à la dégradation de leurs substrats cibles (glucanes, xylanes et lignine, respectivement). Dans la seconde étude, l'addition répétée de résidus a eu peu d'effet sur la biomasse microbienne et la dynamique enzymatique, sauf la LAP et la laccase. Ces résultats suggèrent que la qualité des résidus végétaux est le principal facteur déterminant les modes d'action de la biomasse microbienne et de leurs enzymes extracellulaires durant le processus de décomposition dans le sol. Les résultats de la dernière étude ont démontré que l'addition d'azote réprimait la minéralisation du carbone des résidus les moins lignifiés (F2, F2bm1), mais n'a pas affecté celle du résidu plus lignifié (F292bm3) au cours de la décomposition à long terme. L'ABTS est apparu comme un meilleur substrat que le L-DOPA, le pyrogallol et le TMB pour estimer les activités phénoloxydase et peroxydase.Mots clés: décomposition, biomasse microbienne, enzymes extracellulaires, qualité des résidus, maïsPlant residue decomposition plays a pivotal role in the biogeochemical cycling of nutrients and influences ecosystem functioning. The intrinsic biochemical composition of plant residues is a key factor influencing decomposition processes in soil while the majority of biochemical reactions in soil, related to the biodegradation of plant residues, are catalyzed by extracellular enzymes produced by microorganisms. The overall goal of this research study was to gain fundamental knowledge regarding the impact of residue quality on soil microbial functions and the principles by which soil enzymes mediate plant residue decomposition. This goal was achieved in three parts: 1) to determine the role of the initial residue community i.e. microorganisms and enzymes from the epiphytic and endophytic compartments and effect of plant residue quality on the extracellular enzyme kinetics during the decomposition process in soil 2) to investigate the effect of soil microbial functions (microbial biomass and extracellular enzymes) on the subsequent residue decomposition in the same soil 3) to explore the interactions between nitrogen availability and the decomposition of phenolic compounds through the action of oxydo-reductase enzymes activities and to develop a method to measure these activities in contrasted soils using a single substrate. The general approach of this study was to select plant residues with variations in their chemical quality to obtain contrasted C mineralization kinetics. Maize (Zea mays L.) was selected as a model plant because of variations in chemical and structural characteristics (Mexxal, F2, F2bm1, F292bm3) of aerial (leaves, internodes) and underground parts (roots). 13C-labeled flax stems were used to quantify accurately carbon mineralization in different carbon pools. To assess the relationships between plant residue quality and associated soil biological functions, controlled microcosm experiments were performed using agricultural and forest soils. Carbon mineralization and chemical characteristics (C and N contents, total sugars and lignin contents) of the plant residue, microbial biomass and enzyme activities (L-leucine aminopeptidase (LAP), cellobiohydrolase (CBH-1), xylanase, cellulase and laccase) were determined at different stages of decomposition. The results of first study indicated that activities of epiphytic and endogenic microorganisms were of the same order of magnitude in case of roots while the activities of specific enzymes (cellulase, xylanase and laccase) were highly correlated to the degradation of their target substrates (glucans, xylans and lignin, respectively). In the second study, little effect of repeated residue addition was observed on microbial biomass and enzyme dynamics except LAP and laccase. These results suggest that plant residue quality is the main factor which determines the fate/patterns of microbial biomass and their extracellular enzymes during decomposition process in soil. The results of last study demonstrated that nitrogen addition repressed the carbon mineralization of less lignified residues (F2, F2bm1) but did not affect more lignified residue (F292bm3) in long term decomposition. For estimation of phenol oxidase and peroxidase activities, ABTS appeared as a better substrate than L-DOPA, pyrogallol and TMB.Key words: decomposition, microbial biomass, extracellular enzymes, residue quality, maize
10
Nguyen, Trung Hai [Verfasser], Anthony [Akademischer Betreuer] Whitbread, Klaus [Gutachter] Dittert, and Marife [Gutachter] Corre. "Measuring and modelling the dynamics of carbon and nitrogen mineralization from diverse plant residues in soil – plant systems / Trung Hai Nguyen. Betreuer: Anthony Whitbread. Gutachter: Klaus Dittert ; Marife Corre." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2016. http://d-nb.info/1105036243/34.
Full text
11
Landzela, Besule. "Effects of BT Maize (MON810) crop and its residues on selected soil biological properties and N and P release in a sandy loam soil from Alice, Eastern Cape, South Africa." Thesis, University of Fort Hare, 2013. http://hdl.handle.net/10353/d1007542.
Full textAbstract:
There are apprehensions that genetic modification of maize with Bacillus thuringiensis (Bt) may have negative effects on soil biodiversity, ecosystem processes and functions. This study aimed at determining the effect of Bt maize crop, Bt maize residues and its genetic modification on microbial biomass carbon (MBC), selected enzyme activities, vesicular arbuscular mycorrhizal (VAM) fungi and N and P release patterns. The study was conducted under field, glasshouse and laboratory conditions. In 2010/2011 season, four maize cultivars; DKC 61-25B (Bt), DKC 61-24 (non-Bt), PAN 6Q-321B (Bt) and PAN6777 (non-Bt) were planted. Determination of MBC, enzyme activities and fungal spore count was done at 42, 70, and 105 days after planting (DAP). A loam soil amended with Bt or non-Bt maize leaf residues from a study of 2009/2010 season was incubated to investigate effects of Bt maize residues on MBC and soil enzyme activities. Leaf residues of Bt and non-Bt maize cultivars (DKC 61-25B, DKC 61-24, PAN 6Q-321B and PAN6777) were used and soil without residues was used as a control. Samples were collected at 7, 28 and 56 days of incubation (DOI). An incubation study was also carried out in the laboratory to determine the effect of Bt maize residues (i.e. leaf, stem and root) and its genetic modification on N and P release patterns. Residues of DKC 61-25B, DKC 61-24, PAN 6Q-321B and PAN6777and soil without residues as a control were incubated in the laboratory. After destructive sampling at 0, 7, 14, 28, and 56 DOI, N in the form of NH4-N and NO3-N and P mineralisation were determined. Amendment of soil with residues enhanced MBC (p < 0.05) at all the sampling dates. For example MBC increased from 95 in the control to 146.3 mg/kg in the DKC 61-25B treatment at the end of the glasshouse trial. In the field DKC 61-25B had 9.1 mg/kg greater MBC than DKC 61-24, while PAN 6Q-321B had 23.9 mg/kg more MBC than PAN6777 at the end of the trial. However, no differences (p < 0.05) were observed in enzyme activities under field and glasshouse conditions except for dehydrogenase that had greater activity where DKC 61-25B and PAN 6777 were grown. There were no differences between the type of residues (Bt and non-Bt) on enzyme activities tested. However, differences were observed among the sampling dates. No effects of Bt maize crop on fungal spore count were observed. Similarly no differences were observed in leaf, stem and root tissues composition between Bt and non-Bt maize cultivars. Net N and P mineralisation from Bt maize cultivars did not differ from that of non-Bt maize cultivars. However, differences were observed among the cultivars. The results of this study suggested that Bt maize with Bt MON810 event can be grown in the central region of the Eastern Cape (EC), South Africa without affecting MBC, soil enzyme activities, VAM, and release of N and P nutrients from its residues.
12
Schall, William Lawrence 1954. "SOIL RESIDUES AND PERSISTENCE OF PREEMERGENCE HERBICIDES ASSOCIATED WITH USE ON ORNAMENTAL CROPS, TURF AND LANDSCAPE PLANTINGS." Thesis, The University of Arizona, 1987. http://hdl.handle.net/10150/276381.
Full text
13
Silva, Mariana Pina da [UNESP]. "Coberturas vegetais e adubação fosfatada no desenvolvimento e produtividade do feijoeiro cultivado no período de inverno em sistema plantio direto." Universidade Estadual Paulista (UNESP), 2012. http://hdl.handle.net/11449/106145.
Full textAbstract:
Made available in DSpace on 2014-06-11T19:35:15Z (GMT). No. of bitstreams: 0
Previous issue date: 2012-02-29Bitstream added on 2014-06-13T18:46:45Z : No. of bitstreams: 1
silva_mp_dr_ilha.pdf: 1046855 bytes, checksum: ed7d2f423c1e4d7223ecfca99890e8fd (MD5)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
A utilização de resíduos vegetais no solo é uma prática cultural antiga. No entanto, com o passar dos anos, em função da utilização de fertilizantes químicos, esta prática foi perdendo interesse, porém recentemente tem despertado novamente a atenção por parte dos produtores e pesquisadores. O trabalho teve como objetivo analisar o crescimento, produtividade e qualidade fisiológica do feijoeiro de inverno irrigado cultivado após diferentes plantas de cobertura, bem como as possíveis interações dessa pratica com diferentes doses de P 2O5 em semeadura, e a influência das plantas de cobertura sobre as características químicas e físicas do solo. A pesquisa foi conduzida no período de inverno de 2010 e 2011, na Fazenda de Ensino, Pesquisa e Extensão da Faculdade de Engenharia do Campus de Ilha Solteira – UNESP, localizada no Município de Selvíria/MS. O delineamento experimental foi o de blocos casualizados, em esquema de parcelas subdivididas com 4 repetições. Constituídos pela combinação de plantas de cobertura (milheto, Crotalaria juncea, mucuna-preta, guandu, milheto + Crotalaria juncea, milheto + guandu e milheto + mucuna-preta), além de ser também utilizada uma área em pousio, e níveis P2O5 em semeadura, constituídos por ausência de adubação fosfatada e doses de P2O5 (60, 90 e 120 kg ha-1). Foram avaliados: porcentagem de recobrimento, produção e teor de nutrientes na matéria seca das culturas de cobertura; teor de nutrientes nas folhas de feijoeiro; matéria seca das plantas; componentes de produção, produtividade e qualidade fisiológica das sementes. Foram realizadas avaliações físicas e químicas do solo. De acordo com os resultados, pode se concluir que: o uso de palhada de Crotalaria juncea, milheto + Crotalaria juncea e milheto + mucuna-preta proporcionaram melhores condições...
The use of plant residues in soil is an ancient cultural practice. However, over the years, depending on the use of chemical fertilizers, this practice was losing interest, but recently has attracted renewed attention from producers and researchers. The study aimed to analyze the growth, yield and physiological quality of irrigated winter common bean cultivated after different cover crops, as well as possible interactions of practice with different doses of P2O5 at sowing, and the influence of cover crops on the chemical characteristics and physical soil. The survey was conducted during winter 2010 and 2011, at the Unesp experimental farm, Ilha Solteira campus, in Selviria, Mato Grosso do Sul state, Brazil. The experimental design was a randomized block in split plot with four replications. Constituted by the combination of cover crops (millet, sunn hemp, velvet bean, pigeon pea, pearl millet + sunn hemp, pearl millet + millet + pigeon pea and velvet bean), and is also used in a fallow field, and P 2O5 levels in seeding consisting of the absence of phosphate and levels of P2O5 (60, 90 and 120 kg ha-1). Were evaluated: percentage of coverage, production and nutrient content in dry matter of cover crops, nutrient content in bean leaves, plant dry matter, yield components, yield and physiological quality of seeds. Evaluations were carried out physical and chemical soil in relation to the use of cover crops. According to the results, it can be concluded that the use of straw sunn hemp, consortia millet + sunn hemp and millet + black velvet bean provided better conditions for the production of beans and economy in the application of phosphorus in no- tillage system, the species used as cover caused changes in soil chemical properties, the highest values of macroporosity and lower bulk density occurring in layer 0-0,20... (Complete abstract click electronic access below)
14
Hilscher, André [Verfasser], Heike E. [Akademischer Betreuer] Knicker, Jörg [Akademischer Betreuer] Völkel, and Christian [Akademischer Betreuer] Siewert. "Degradation, chemical alteration and stabilisation of pyrogenic plant residues in soil / André Hilscher. Gutachter: Heike E. Knicker ; Jörg Völkel ; Christian Siewert. Betreuer: Heike E. Knicker." München : Universitätsbibliothek der TU München, 2011. http://d-nb.info/1014329604/34.
Full text
15
Costa, Claudio Hideo Martins da [UNESP]. "Efeito residual da aplicação superficial de calcário e gesso nas culturas de soja, aveia-preta e sorgo granífero." Universidade Estadual Paulista (UNESP), 2011. http://hdl.handle.net/11449/86428.
Full textAbstract:
Made available in DSpace on 2014-06-11T19:22:16Z (GMT). No. of bitstreams: 0
Previous issue date: 2011-07-22Bitstream added on 2014-06-13T20:28:26Z : No. of bitstreams: 1
costa_chmc_me_botfca.pdf: 444896 bytes, checksum: 79a884c18686d0a77b3357b8cbc1bcfb (MD5) Bitstreams deleted on 2015-08-07T12:19:54Z: costa_chmc_me_botfca.pdf,. Added 1 bitstream(s) on 2015-08-07T12:20:56Z : No. of bitstreams: 1
000678831.pdf: 1444305 bytes, checksum: d3e614871d6cd55de66eda01f9f2bdd0 (MD5)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
No sistema plantio direto praticamente não há revolvimento do solo e o consequente acúmulo de fertilizantes na superfície acelera o processo de acidificação, contínuo e acentuado que ocorre naturalmente em solos de regiões úmidas, onde, geralmente, é observada baixa disponibilidade de nutrientes e elevados teores de alumínio. Assim, da mesma forma que no sistema de cultivo convencional, no sistema plantio direto também existe a necessidade de aplicação de insumos em superfície, especialmente, materiais corretivos de acidez. Dentro deste enfoque, o trabalho foi desenvolvido na Fazenda Experimental Lageado, pertencente à Faculdade de Ciências Agronômicas – UNESP, Campus de Botucatu (SP), dando continuidade a um projeto de pesquisa que vem sendo conduzido desde 2002, com o objetivo de avaliar o efeito residual da aplicação superficial de corretivos na correção da acidez do solo, bem como na nutrição, na produtividade das culturas da soja e do sorgo e na produção de matéria seca e acúmulo de nutrientes da aveia-preta em região de inverno seco. O delineamento experimental utilizado foi em blocos casualizados em parcelas subdivididas, com 4 repetições. As parcelas foram constituídas por quatro doses de calcário (0, 1000, 2000 e 4000 kg ha-1) e as subparcelas por duas doses de gesso agrícola (0 e 2100 kg ha-1), aplicado em novembro 2004. Como cultura de verão foi utilizada a cultura da soja e na entressafra as culturas da aveia-preta e sorgo granífero. A aplicação de calcário em superfície promoveu diminuição da acidez e elevação nos teores de fósforo, cálcio, magnésio e matéria orgânica, em praticamente todo perfil do solo. A aplicação de gesso agrícola promoveu aumentos nos 2 teores de Ca trocável e S-SO42-, e diminuição no teor de Al trocável no solo...
In no tillage system the absence of soil mobilization consequently decreases places fertilizers on surface, affecting the acidification process. Like in conventional system, in no tillage it is also necessary input application, especially materials for acidity correction. The experiment was carried out in an experimental area, in the city of Botucatu (SP, Brazil), continuing a research project that has been conducted since 2002, to evaluate the long-term effects of surface application of lime and gypsum on acidity correction, nutrition, yield of soybean and sorghum, and dry matter production and nutrients accumulation on black oat in a dry winter region. The experimental design was the completely randomized with subdivided plots and four replications. The mains plots consisted of four dolomite limestone levels (0, 1000, 2000 e 4000 kg ha-1) and the subplots consisted areas with and without gypsum (0 and 2100 kg ha-1), applied in November 2004. Soybean was the summer crops and the off-season crops are black oat and grain sorghum Lime surface application reduced soil acidity and increased phosphorus, calcium, magnesium and organic matter, practically all the soil profile. Phosphogypsum application promoted increasing exchangeable Ca and S-SO42- contents, and decreased exchangeable Al in the soil, favoring the effects of surface liming on soil properties, mainly the surface layer (0-0.20 m). Base saturation values obtained at a depth of 0-0.20 m with liming were lower than those estimated by BS method, even with phosphogypsum application. Liming increased, on soybeans, foliar contents of N, P, Ca, Mg and S in 2008/09, and N, Ca and Mg, in 2009/10. In the presence of phosphogypsum increased the levels of N In no tillage system the absence of soil mobilization consequently... (Complete abstract click electronic access below)
16
Silva, Mariana Pina da. "Coberturas vegetais e adubação fosfatada no desenvolvimento e produtividade do feijoeiro cultivado no período de inverno em sistema plantio direto /." Ilha Solteira : [s.n.], 2012. http://hdl.handle.net/11449/106145.
Full textAbstract:
Orientador: Orivaldo ArfBanca: Salatiér Buzetti
Banca: Marco Eustaquio de Sa
Banca: Rita de Cássia Félix Alvarez
Banca: Flávio Ferreira da Silva Binotti
Resumo: A utilização de resíduos vegetais no solo é uma prática cultural antiga. No entanto, com o passar dos anos, em função da utilização de fertilizantes químicos, esta prática foi perdendo interesse, porém recentemente tem despertado novamente a atenção por parte dos produtores e pesquisadores. O trabalho teve como objetivo analisar o crescimento, produtividade e qualidade fisiológica do feijoeiro de inverno irrigado cultivado após diferentes plantas de cobertura, bem como as possíveis interações dessa pratica com diferentes doses de P 2O5 em semeadura, e a influência das plantas de cobertura sobre as características químicas e físicas do solo. A pesquisa foi conduzida no período de inverno de 2010 e 2011, na Fazenda de Ensino, Pesquisa e Extensão da Faculdade de Engenharia do Campus de Ilha Solteira - UNESP, localizada no Município de Selvíria/MS. O delineamento experimental foi o de blocos casualizados, em esquema de parcelas subdivididas com 4 repetições. Constituídos pela combinação de plantas de cobertura (milheto, Crotalaria juncea, mucuna-preta, guandu, milheto + Crotalaria juncea, milheto + guandu e milheto + mucuna-preta), além de ser também utilizada uma área em pousio, e níveis P2O5 em semeadura, constituídos por ausência de adubação fosfatada e doses de P2O5 (60, 90 e 120 kg ha-1). Foram avaliados: porcentagem de recobrimento, produção e teor de nutrientes na matéria seca das culturas de cobertura; teor de nutrientes nas folhas de feijoeiro; matéria seca das plantas; componentes de produção, produtividade e qualidade fisiológica das sementes. Foram realizadas avaliações físicas e químicas do solo. De acordo com os resultados, pode se concluir que: o uso de palhada de Crotalaria juncea, milheto + Crotalaria juncea e milheto + mucuna-preta proporcionaram melhores condições... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The use of plant residues in soil is an ancient cultural practice. However, over the years, depending on the use of chemical fertilizers, this practice was losing interest, but recently has attracted renewed attention from producers and researchers. The study aimed to analyze the growth, yield and physiological quality of irrigated winter common bean cultivated after different cover crops, as well as possible interactions of practice with different doses of P2O5 at sowing, and the influence of cover crops on the chemical characteristics and physical soil. The survey was conducted during winter 2010 and 2011, at the Unesp experimental farm, Ilha Solteira campus, in Selviria, Mato Grosso do Sul state, Brazil. The experimental design was a randomized block in split plot with four replications. Constituted by the combination of cover crops (millet, sunn hemp, velvet bean, pigeon pea, pearl millet + sunn hemp, pearl millet + millet + pigeon pea and velvet bean), and is also used in a fallow field, and P 2O5 levels in seeding consisting of the absence of phosphate and levels of P2O5 (60, 90 and 120 kg ha-1). Were evaluated: percentage of coverage, production and nutrient content in dry matter of cover crops, nutrient content in bean leaves, plant dry matter, yield components, yield and physiological quality of seeds. Evaluations were carried out physical and chemical soil in relation to the use of cover crops. According to the results, it can be concluded that the use of straw sunn hemp, consortia millet + sunn hemp and millet + black velvet bean provided better conditions for the production of beans and economy in the application of phosphorus in no- tillage system, the species used as cover caused changes in soil chemical properties, the highest values of macroporosity and lower bulk density occurring in layer 0-0,20... (Complete abstract click electronic access below)
Doutor
17
Costa, Claudio Hideo Martins da 1985. "Efeito residual da aplicação superficial de calcário e gesso nas culturas de soja, aveia-preta e sorgo granífero /." Botucatu : [s.n.], 2011. http://hdl.handle.net/11449/86428.
Full textAbstract:
Orientador: Carlos Alexandre Costa CrusciolBanca: José Salvador Simoneti Foloni
Banca: Eduardo Fávero Caires
Resumo: No sistema plantio direto praticamente não há revolvimento do solo e o consequente acúmulo de fertilizantes na superfície acelera o processo de acidificação, contínuo e acentuado que ocorre naturalmente em solos de regiões úmidas, onde, geralmente, é observada baixa disponibilidade de nutrientes e elevados teores de alumínio. Assim, da mesma forma que no sistema de cultivo convencional, no sistema plantio direto também existe a necessidade de aplicação de insumos em superfície, especialmente, materiais corretivos de acidez. Dentro deste enfoque, o trabalho foi desenvolvido na Fazenda Experimental Lageado, pertencente à Faculdade de Ciências Agronômicas - UNESP, Campus de Botucatu (SP), dando continuidade a um projeto de pesquisa que vem sendo conduzido desde 2002, com o objetivo de avaliar o efeito residual da aplicação superficial de corretivos na correção da acidez do solo, bem como na nutrição, na produtividade das culturas da soja e do sorgo e na produção de matéria seca e acúmulo de nutrientes da aveia-preta em região de inverno seco. O delineamento experimental utilizado foi em blocos casualizados em parcelas subdivididas, com 4 repetições. As parcelas foram constituídas por quatro doses de calcário (0, 1000, 2000 e 4000 kg ha-1) e as subparcelas por duas doses de gesso agrícola (0 e 2100 kg ha-1), aplicado em novembro 2004. Como cultura de verão foi utilizada a cultura da soja e na entressafra as culturas da aveia-preta e sorgo granífero. A aplicação de calcário em superfície promoveu diminuição da acidez e elevação nos teores de fósforo, cálcio, magnésio e matéria orgânica, em praticamente todo perfil do solo. A aplicação de gesso agrícola promoveu aumentos nos 2 teores de Ca trocável e S-SO42-, e diminuição no teor de Al trocável no solo... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: In no tillage system the absence of soil mobilization consequently decreases places fertilizers on surface, affecting the acidification process. Like in conventional system, in no tillage it is also necessary input application, especially materials for acidity correction. The experiment was carried out in an experimental area, in the city of Botucatu (SP, Brazil), continuing a research project that has been conducted since 2002, to evaluate the long-term effects of surface application of lime and gypsum on acidity correction, nutrition, yield of soybean and sorghum, and dry matter production and nutrients accumulation on black oat in a dry winter region. The experimental design was the completely randomized with subdivided plots and four replications. The mains plots consisted of four dolomite limestone levels (0, 1000, 2000 e 4000 kg ha-1) and the subplots consisted areas with and without gypsum (0 and 2100 kg ha-1), applied in November 2004. Soybean was the summer crops and the off-season crops are black oat and grain sorghum Lime surface application reduced soil acidity and increased phosphorus, calcium, magnesium and organic matter, practically all the soil profile. Phosphogypsum application promoted increasing exchangeable Ca and S-SO42- contents, and decreased exchangeable Al in the soil, favoring the effects of surface liming on soil properties, mainly the surface layer (0-0.20 m). Base saturation values obtained at a depth of 0-0.20 m with liming were lower than those estimated by BS method, even with phosphogypsum application. Liming increased, on soybeans, foliar contents of N, P, Ca, Mg and S in 2008/09, and N, Ca and Mg, in 2009/10. In the presence of phosphogypsum increased the levels of N In no tillage system the absence of soil mobilization consequently... (Complete abstract click electronic access below)
Mestre
18
Mewes, Paul. "Persistence of exogenous organic carbon in soil as a cultivation property." Doctoral thesis, Humboldt-Universität zu Berlin, 2017. http://dx.doi.org/10.18452/18143.
Full textAbstract:
Eine biochemische Indikation des Anteils exogener organischer Kohlenstoffquellen (EOC), der nach dem Eintrag potenziell im Boden verbleibt (Cpot) wurde entwickelt. Haupthypothese dieser Studie war, dass der Abbau von EOC durch die biochemische Zusammensetzung vorhergesagt werden kann, welche bei Pflanzenrückständen von der Kulturart, dem Pflanzenrückstandstyp sowie dem Anbausystem und im Allgemeinen vom Ausgangssubstrat organischer Düngestoffe und der EOC-Kategorie (pyrogen , mikrobiell und pflanzlich) beeinflusst wird. Zunächst wurden Pflanzenrückstände im Energiepflanzenanbau zur Biogasgewinnung (Restpflanze / Stroh, Stoppeln, Grobwurzeln, Feinwurzeln, natürlicher Bestandsabfall) von Mais, Sorghum, Sudangras, Wintergetreide, Hafer, Erbse in Einzel-, Zwei- und Mischkultursystemen betrachtet. In einem zweiten Schritt wurden Pflanzenrückstände im Allgemeinen mit organischen Düngern, Komposten, Rückständen aus anaerober Vergärung in der Biogasproduktion (Gärrückstände) und Biokohlen verglichen. Die biochemische Zusammensetzung von EOC wurde durch die Konzentrationen von Kohlenstoff- (C), Stickstoff (N), wasserlöslicher Kohlehydrate (WSC), Hemizellulose (HEM), Zellulose (CEL) und Lignin (LIC) in g pro kg Trockenmasse dargestellt. In Inkubationsversuchen wurde EOC gleichmäßig mit Boden vermischt und über 310 Tage die Zugabe-induzierte Kohlendioxid-Freisetzung gemessen. Cpot wurde als Grenzwert der Modellschätzung für die Inkubationsdaten bestimmt. Die Beziehung zwischen biochemischer Zusammensetzung und Cpot wurde durch die Partial-Least-Squares-Regression-Methode abgeleitet. Cpot unterschied sich stärker zwischen verschiedenen organischen Düngestoffen, als speziell zwischen verschiedenen Pflanzenrückständen und konnte durch die biochemische Zusammensetzung vorhergesagt werden. Der Indikator für Cpot (in g C pro kg EOC) wurde als Ipot = 269 + 13 N – 0.5 WSC + 0.7 CEL + 1.5 LIC für Pflanzenrückstände und im Allgemeinen als Ipot = 924 – 1.9 C + 2.0 LIC vorgeschlagen.A biochemical indication for the fraction of exogenous organic carbon (EOC), potentially remaining in soil after application (Cpot) has been developed. Main hypothesis of this study was that decomposition of EOC can be predicted by the biochemical composition, which in case of plant residues is influenced by the crop residue type, crop species and agricultural management and in general depends on the original substrate and category (pyrogen, microbial, and plant-derived EOC) of organic materials. A first set of EOC was created, containing plant residues in energy crop cultivation for biogas production (shoot / straw, stubble, coarse root, fine root, and litter) of maize, sorghum, sudan grass, winter cereal, pea, and oats in single-, double- and intercropping systems. In a second set of EOC, plant residues in general were compared with other organic fertilisers, urban composts, residues of anaerobic fermentation in biogas production (digestates), and biochar. The biochemical composition of EOC was characterised by the concentrations of carbon (C), nitrogen (N), water-soluble carbohydrates (WSC), hemicelluloses (HEM), cellulose (CEL), and lignin (LIC) in g per kg dry matter. In incubation experiments, EOC was homogeneously incorporated into soil and EOC-induced carbon dioxide-release was measured for 310 d. Cpot was determined as modelled limit for the incubation results. Finally, the relation between biochemical composition and Cpot of EOC was evaluated by the partial least squares regression method. Cpot largely varied between different types and categories of EOC, while less variation was obtained between different plant residues. The biochemical composition was predictive for Cpot (expressed as g C per kg EOC), proposing the biochemical indicator as Ipot = 269 + 13 N – 0.5 WSC + 0.7 CEL + 1.5 LIC specifically for plant residues and as Ipot = 924 – 1.9 C + 2.0 LIC for EOC in general.
19
Boyer, Cheryl ReNee' Gilliam Charles Homer Fain Glenn Bradley. "Evaluation of clean chip residual as an alternative substrate for container-grown plants." Auburn, Ala, 2008. http://repo.lib.auburn.edu/EtdRoot/2008/SPRING/Horticulture/Dissertation/Boyer_Cheryl_22.pdf.
Full text
20
Ferreira, Gilberto Alves. "Altura de pastejo da Brachiaria ruziziensis sobre a produção de palhada, atributos físicos, carbono e nitrogênio no solo e produtividade de soja em sistema de integração lavoura pecuária conduzido em latossolo arenoso." Universidade Estadual do Oeste do Paraná, 2013. http://tede.unioeste.br:8080/tede/handle/tede/1446.
Full textAbstract:
Made available in DSpace on 2017-07-10T17:40:44Z (GMT). No. of bitstreams: 1
Gilberto_Alves_Fereira.pdf: 2149647 bytes, checksum: cf5d015f2b3d6a66b8343e8244e8da51 (MD5)
Previous issue date: 2013-08-22The use of forage species in production systems such as integrated crop livestock can be key to improving fertility and increasing productivity of pastures and crops. The objective this study was to evaluate the effects height of grazing of Brachiaria ruziziensis on straw production, on the physical properties of the soil, in levels and stocks of carbon and nitrogen of the soil and in the soybean yield in crop livestock integration system. The experiment was conducted in the Experimental Farm of the Agronomic Institute of Paraná (IAPAR), located in the municipality of Xambrê-PR, in september 2010 to april 2012, during the agricultural year 2010/2011 and 2011/2012. The experimental design used was randomized in blocks, split plot in time (sampling time), with five treatments (grazing height of 10, 20, 30 and 40 cm and an area with no grazing) and three repetitions. Were determined the dry matter the mass of the aerial part of Brachiaria ruziziensis, vegetable residue dry matter and mass of total dry matter. The layers of 0-10, 10-20 and 20-30 cm were studied the density, macroporosity, microporosity, total porosity, gravimetric water, levels and stocks of total organic carbon, particulate carbon and carbon associated with minerals and the levels and stocks of mineral nitrogen and total of the soil. In culture of soy were evaluated the number of plants per meter, height of plants and grain productivity. The dry matter mass of the aerial part of Brachiaria ruziziensis and the total dry matter mass were significant (P<0,05) in the two seasons of evaluation, with higher production in the ungrazed compared to grazed area (P<0,05). The variable dry matter of plant residue was not significant (P>0,05) for the first time and significant in second season (P<0,05). The density, macroporosity, microporosity, total porosity and gravimetric soil moisture were not altered by grazing height and area not grazed at all depths evaluated (P>0,05). Density reduction occurred, increase macroporosity and total porosity in the 0-10 cm layer of soil, at the end of the experiment (P<0,05). There was a higher microporosity after brachiaria in relation to the time after the soybean crop (P <0,05). The levels and stocks of total organic carbon of the soil and its fractions, besides levels and stocks of mineral and total nitrogen of the soil were not altered by grazing heights and the area not grazed (P>0,05). However, there was an increase in levels and stocks of total organic carbon and carbon associated with minerals and a reduction of the particulate carbon of the soil in the final experiment (P<0,05). There was an increase of mineral nitrogen after harvest soybeans for all soil layers (P<0,05), however, the increase of total nitrogen and stocks of the soil occurred only in the 0-10 cm depth, in the last evaluation. The number of plants per meter, plant height and yield of soybean were not affected by the different Heights and the absence of grazing (P>0,05)
O emprego de espécies forrageiras em sistemas de produção como a integração lavoura pecuária pode ser determinante para a melhoria da fertilidade e incremento de produtividade das pastagens e das culturas. O objetivo deste trabalho foi avaliar os efeitos da altura de pastejo de Brachiaria ruziziensis na produção de palhada, nas propriedades físicas do solo, nos teores e estoques de carbono e nitrogênio do solo e na produtividade da soja em sistema de integração lavoura pecuária. O experimento foi conduzido em área da Fazenda Experimental do Instituto Agronômico do Paraná (IAPAR), localizada no município de Xambrê-PR, no período de setembro de 2010 a abril de 2012, durante os anos agrícolas de 2010/2011 e 2011/2012. O delineamento experimental utilizado foi em blocos ao acaso, em parcelas subdivididas no tempo (época de amostragem), com cinco tratamentos (altura de pastejo de 10, 20, 30 e 40 cm e uma área sem pastejo) e três repetições. Foram determinadas a massa de matéria seca da parte aérea de Brachiaria ruziziensis, matéria seca de resíduo vegetal e massa de matéria seca total. Nas camadas de 0-10, 10-20 e 20-30 cm foram estudadas a densidade, macroporosidade, microporosidade, porosidade total, água gravimétrica, teores e estoques de carbono orgânico total, carbono particulado e carbono associados aos minerais do solo e os teores e estoque de nitrogênio mineral e total do solo. Na cultura da soja foram avaliadas o número de plantas por metro, altura das plantas e produtividade de grãos. A massa de matéria seca da parte aérea de Brachiaria ruziziensis e a massa de matéria seca total foram significativas (P<0,05) nas duas épocas de avaliação, com maior produção na área sem pastejo em relação às áreas pastejadas (P<0,05). Já a variável matéria seca de resíduo vegetal não foi significativa (P>0,05) para a primeira época e significativo na segunda época (P<0,05). A densidade, macroporosidade, microporosidade, porosidade total e umidade gravimétrica do solo não foram alteradas pelas alturas de pastejo e área não pastejada em todas as profundidades avaliadas (P>0,05). Ocorreu redução da densidade, aumento da macroporosidade e da porosidade total na camada 0-10 cm do solo, ao final do experimento (P<0,05). Houve maior microporosidade após a braquiária em relação à época após a cultura da soja (P<0,05). Os teores e estoques de carbono orgânico total do solo e suas respectivas frações, além dos teores e estoques de nitrogênio mineral e total do solo não foram alteradas pelas alturas de pastejo e a área não pastejada (P>0,05). Todavia, ocorreu aumento dos teores e estoques de carbono orgânico total e carbono associado aos minerais e redução do carbono particulado do solo ao final do experimento (P<0,05). Houve aumento do nitrogênio mineral após a colheita da soja para todas as camadas do solo (P<0,05), porém, o aumento do nitrogênio total do solo e seus estoques ocorreram apenas na profundidade 0-10 cm, na última avaliação. O número de plantas por metro, a altura das plantas e a produtividade da cultura da soja não foram influenciados pelas diferentes alturas e pela ausência do pastejo (P>0,05)
21
Condron, Leo M. "Chemical nature and plant availability of phosphorus present in soils under long-term fertilised irrigated pastures in Canterbury, New Zealand." Lincoln College, University of Canterbury, 1986. http://hdl.handle.net/10182/1875.
Full textAbstract:
Soil P fractionation was used to examine changes in soil inorganic and organic P under grazed irrigated pasture in a long-term field trial at Winchmore in Mid-Canterbury. The soil P fractionation scheme used involved sequential extractions of soil with O.5M NaHCO₃ @ pH 8.5 (NaHCO₃ P), 0.1M NaOH (NaOH I P), 1M HCl (HCl P) and 0.1M NaOH (NaOH II P). The Winchmore trial comprised 5 treatments: control (no P since 1952), 376R (376 kg superphosphate ha⁻¹ yr⁻¹ 1952-1957, none since), 564R (564 kg superphosphate ha⁻¹ yr⁻¹ 1952-1957, none since) 188PA (188 kg superphosphate ha⁻¹ yr⁻¹ since 1952) and 376PA (376 kg superphosphate ha⁻¹ yr⁻¹ since 1952: Topsoil (0-7.5cm) samples taken from the different treatments in 1958, 1961, 1965, 1968, 1971, 1974 and 1977 were used in this study. Changes in soil P with time showed that significant increases in soil inorganic P occurred in the annually fertilised treatments (l88PA, 376PA). As expected, the overall increase in total soil inorganic P between 1958 and 1977 was greater in the 376PA treatment (159 µg P g⁻¹) than that in the 188PA treatment (37 µg P g⁻¹). However, the chemical forms of inorganic P which accumulated in the annually fertilised treatments changed with time. Between 1958 and 1971 most of the increases in soil inorganic P in these treatments occurred in the NaHCO₃ and NaOH I P fractions. On the other hand, increases in soil inorganic P in the annually fertilised treatments between 1971 and 1977 were found mainly in the HCl and NaOH II P fractions. These changes in soil P forms were attributed to the combined effects of lime addition in 1972 and increased amounts of sparingly soluble apatite P and iron-aluminium P in the single superphosphate applied during the 1970's. In the residual fertiliser treatments (376R, 564R) significant decreases in all of the soil inorganic P fractions (i.e. NaHCO₃ P, NaOH I P, HCl P, NaOH II p) occurred between 1958 and 1977 following the cessation of P fertiliser inputs in 1957. This was attributed to continued plant uptake of P accumulated in the soil from earlier P fertiliser additions. However, levels of inorganic P in the different soil P fractions in the residual fertiliser treatments did not decline to those in the control which indicated that some of the inorganic P accumulated in the soil from P fertiliser applied between 1952 and 1957 was present in very stable forms. In all treatments, significant increases in soil organic P occurred between 1958 and 1971. The overall increases in total soil organic P were greater in the annually fertilised treatments (70-86 µg P g⁻¹) than those in the residual fertiliser (55-64 µg P g⁻¹) and control (34 µg P g⁻¹) treatments which reflected the respective levels of pasture production in the different treatments. These increases in soil organic P were attributed to the biological conversion of native and fertiliser inorganic P to organic P in the soil via plant, animal and microbial residues. The results also showed that annual rates of soil organic P accumulation between 1958 and 1971 decreased with time which indicated that steady-state conditions with regard to net 'organic P accumulation were being reached. In the residual fertiliser treatments, soil organic P continued to increase between 1958 and 1971 while levels of soil inorganic P and pasture production declined. This indicated that organic P which accumulated in soil from P fertiliser additions was more stable and less available to plants than inorganic forms of soil P. Between 1971 and 1974 small (10-38 µg P g⁻¹) but significant decreases in total soil organic P occurred in all treatments. This was attributed to increased mineralisation of soil organic P as a result of lime (4 t ha⁻¹) applied to the trial in 1972 and also to the observed cessation of further net soil organic P accumulation after 1971. Liming also appeared to affect the chemical nature of soil organic P as shown by the large decreases in NaOH I organic P(78-88 µg P g⁻¹) and concomitant smaller increases in NaOH II organic P (53-65 µg P g⁻¹) which occurred in all treatments between 1971 and 1974. The chemical nature of soil organic P in the Winchmore long-term trial was also investigated using 31p nuclear magnetic resonance (NMR) spectroscopy and gel filtration chromatography. This involved quantitative extraction of organic P from the soil by sequential extraction with 0.1M NaOH, 0.2M aqueous acetylacetone (pH 8.3) and 0.5M NaOH following which the extracts were concentrated by ultrafiltration. Soils (0-7.5cm) taken from the control and 376PA annually fertilised treatments in 1958, 1971 and 1983 were used in this study. 31p NMR analysis showed that most (88-94%) of the organic P in the Winchmore soils was present as orthophosphate monoester P while the remainder was found as orthophosphate diester and pyrophosphate P. Orthophosphate monoester P also made up almost all of the soil organic P which accumulated in the 376PA treatment between 1958 and 1971. This indicated that soil organic P in the 376PA and control treatments was very stable. The gel filtration studies using Sephadex G-100 showed that most (61-83%) of the soil organic P in the control and 376PA treatments was present in the low molecular weight forms (<100,000 MW), although the proportion of soil organic P in high molecular weight forms (>100,000 MW) increased from 17-19% in 1958 to 38-39% in 1983. The latter was attributed to the microbial humification of organic P and indicated a shift toward more complex and possibly more stable forms of organic P in the soil with time. Assuming that the difference in soil organic P between the control and 376PA soils sampled in 1971 and 1983 represented the organic P derived from P fertiliser additions, results showed that this soil organic P was evenly distributed between the high and low molecular weight fractions. An exhaustive pot trial was used to examine the relative availability to plants of different forms of soil inorganic and organic P in long-term fertilised pasture soils. This involved growing 3 successive crops of perennial ryegrass (Lolium perenne) in 3 Lismore silt loam (Udic Ustochrept) soils which had received different amounts of P fertiliser for many years. Two of the soils were taken from the annually fertilised treatments in the Winchmore long term trial (188PA, 376PA) and the third (Fairton) was taken from a pasture which had been irrigated with meatworks effluent for over 80 years (65 kg P ha⁻¹ yr⁻¹). Each soil was subjected to 3 treatments, namely control (no nutrients added), N100 and N200. The latter treatments involved adding complete nutrient solutions with different quantities of N at rates of 100kg N ha⁻¹ (N100) and 200kg N ha⁻¹ (N200) on an area basis. The soil P fractionation scheme used was the same as that used in the Winchmore long-term trial study (i.e. NaHCO₃ P, NaOH I P, HCl P, NaOH II p). Results obtained showed that the availability to plants of different extracted inorganic P fractions, as measured by decreases in P fractions before and after 3 successive crops, followed the order: NaHCO₃ P > NaOH I P > HCl P = NaOH II P. Overall decreases in the NaHCO₃ and NaOH I inorganic P fractions were 34% and 16% respectively, while corresponding decreases in the HCl and NaOH II inorganic P fractions were small «10%) and not significant. However, a significant decrease in HCl P (16%) was observed in one soil (Fairton-N200 treatment) which was attributed to the significant decrease in soil pH (from 6.2 to 5.1) which occurred after successive cropping. Successive cropping had little or no effect on the levels of P in the different soil organic P fractions. This indicated that net soil organic P mineralisation did not contribute significantly to plant P uptake over the short-term. A short-term field experiment was also conducted to examine the effects of different soil management practices on the availability of different forms of P to plants in the long-term fertilised pasture soils. The trial was sited on selected plots of the existing annually fertilised treatments in the Winchmore long-term trial (188PA, 376PA) and comprised 5 treatments: control, 2 rates of lime (2 and 4 t ha⁻¹ ) , urea fertiliser (400kg N ha⁻¹ ) and mechanical cultivation. The above ground herbage in the uncultivated treatments was harvested on 11 occasions over a 2 year period and at each harvest topsoil (0-7.5 cm) samples were taken from all of the treatments for P analysis. The soil P fractionation scheme used in this particular trial involved sequential extractions with 0.5M NaHCO₃ @ pH 8.5 (NaHCO₃ P), 0.1M NaOH (NaOH P), ultrasonification with 0.1M NaOH (sonicate-NaOH p) and 1M HCl (HCl P). In addition, amounts of microbial P in the soils were determined. The results showed that liming resulted in small (10-21 µg P g⁻¹) though significant decreases in the NaOH soil organic P fraction in the 188PA and 376PA plots. Levels of soil microbial P were also found to be greater in the limed treatments compared with those in the controls. These results indicated that liming increased the microbial mineralisation of soil organic P in the Winchmore soils. However, pasture dry matter yields and P uptake were not significantly affected. Although urea significantly increased dry matter yields and P uptake, it did not appear to significantly affect amounts of P in the different soil P fractions. Mechanical cultivation and the subsequent fallow period (18 months) resulted in significant increases in amounts of P in the NaHCO₃ and NaOH inorganic P fractions. This was attributed to P released from the microbial decomposition of plant residues, although the absence of plants significantly reduced levels of microbial P in the cultivated soils. Practical implications of the results obtained in the present study were presented and discussed.
22
Müller, Anja-Christine [Verfasser], Edgar [Akademischer Betreuer] Peiter, and Eckhard [Akademischer Betreuer] George. "Underground networks of arbuscular mycorrhizal fungi : development and functioning of the external mycelium of Glomus mosseae and G. intraradices in soil substrate and plant residues / Anja-Christine Müller. Betreuer: Edgar Peiter ; Eckhard George." Halle, Saale : Universitäts- und Landesbibliothek Sachsen-Anhalt, 2013. http://d-nb.info/1035182211/34.
Full text
23
Xu, Jialu [Verfasser], and Sabine [Akademischer Betreuer] Gruber. "Effects of woody plants and their residues on crop yield, weedsand soil carbon fractions in selected arable cropping systems / Jialu Xu ; Betreuer: Sabine Gruber." Hohenheim : Kommunikations-, Informations- und Medienzentrum der Universität Hohenheim, 2018. http://d-nb.info/1155237161/34.
Full text
24
Basanta, Maria Del Valle. "Dinâmica do nitrogênio na cultura de cana-de-açúcar em diferentes sistemas de manejo de resíduos da colheita." Universidade de São Paulo, 2004. http://www.teses.usp.br/teses/disponiveis/11/11136/tde-08092004-163918/.
Full textAbstract:
Com o objetivo de avaliar, durante cinco anos, o efeito de dois sistemas de manejo dos resíduos culturais, colheita tradicional com queima prévia (CQ) e colheita sem queima (SQ), sobre a produtividade da cana-de-açúcar e a dinâmica do nitrogênio no sistema solo-planta em função do nitrogênio introduzido através do fertilizante e dos resíduos culturais, foi instalado um experimento com adubação no plantio com 63kg.ha-1 de N com os seguintes tratamentos: (T1) 15N-SA (sulfato de amônio) e colheita SQ, recebendo na primeira colheita o total dos resíduos não marcados produzidos no T2; (T2) SA e colheita SQ, recebendo na primeira colheita o total dos resíduos marcados produzidos no T1; e (T3) 15N-SA e colheita CQ. Anualmente, na época da colheita, a planta foi dividida em colmos, ponteiros e palhada; o solo (<2000µm) foi amostrado nas camadas de 0-15, 15-30 e 30-50cm, e foram determinadas as frações granulométricas correspondentes a tamanho de partícula 200-2000µm (Fl, fração orgânica leve e Fp, fração mineral pesada), 53-200µm (Fom, fração organo-mineral) e <53µm (Fsa, fração silte-argila). As variáveis determinadas foram produtividade de colmos (Mg.ha-1); nitrogênio total (Nt, kg.ha-1), nitrogênio derivado do fertilizante (QNddF, kg.ha-1) e nitrogênio derivado dos resíduos (QNddR, kg.ha-1) em solo e planta; e carbono total no solo (C, Mg.ha-1). Em todos os anos, observou-se maior produtividade (p<0,05) e maior absorção de nitrogênio (p<0,05) no tratamento CQ em relação ao SQ. Considerando a quantidade de resíduos que permaneceu no sistema e seu conteúdo de Nt, o potencial estimado de reciclagem de N no sistema SQ foi de 65% do Nt contido na parte aérea da cultura. O potencial de perda de Nt foi estimado em 85% do nitrogênio da parte aérea no sistema CQ. Na colheita da cana-planta, a recuperação do QNddF no sistema solo-planta foi de 46,9kg.ha-1, sendo que 63,0% foi medido na parte aérea. Nos anos seguintes, observou-se uma diminuição exponencial do NddF recuperado na parte aérea da planta. No sistema SQ, o NddF recuperado no sistema solo-planta no segundo ano foi significativamente superior (p<0,05) que no sistema CQ. Aproximadamente 95% do NddR ficou imobilizado no solo, permanecendo no sistema no final da colheita da quarta cana-soca. Os conteúdos de carbono e nitrogênio nas frações do solo apresentaram valores crescentes na seguinte ordem: Fsa>Fom>Fl. A Fsa continha mais de 70% do C e do Nt do solo. O sistema de manejo dos resíduos não influenciou o conteúdo de carbono do solo, nem sua distribuição nas frações granulométricas. Na avaliação da colheita da última cana-soca (2002), o sistema SQ apresentou valores de Nt superiores (p<0,05%) em Fl e Fom na camada 0-15cm, e em Fom na camada 30-50cm. Os conteúdos de NddF e NddR nas frações do solo aumentaram na ordem Fsa>Fom>Fl. No sistema SQ, na colheita da primeira cana-soca em 1999, a ordem no conteúdo de NddF foi Fl>Fom>Fsa. No mesmo ano, a ordem no conteúdo de NddR foi Fl>Fsa>Fom. O enriquecimento em 15N dos resíduos gerados durante o ciclo da cana-planta explica os maiores conteúdos de 15N em Fl.To evaluate during five years the effects of two trash management systems in a sugarcane crop, the traditional harvest system with trash burning before harvest (CQ) and an alternative system without trash burning (SQ), on stalk yield and nitrogen nutrition of the crop, and on the distribution in the soil-plant system of the nitrogen introduced by fertilizer and trash, an experiment was carried out in Piracicaba, SP, Brazil, with the following treatments fertilized at planting with 63kg.ha-1 of N: (T1) 15N-labeled ammonium sulfate (AS), harvested with SQ system, and after the first harvest received all the unlabeled trash from T2; (T2) unlabeled AS, harvested with the SQ system, and after the first harvest received all the 15N-labeled trash from T1; and (T3) 15N-AS, and harvested with the CQ system. Annually, at harvest, plants were divided in stalks, tips and residues; and the soil (<2000µm) was sampled in the 0-15, 15-30 and 30-50cm layers, and physically fractionated in particle sizes of 200-2000µm (Fl, light organic fraction, and Fp, heavy mineral fraction), 53-200µm (Fom, organomineral fraction) and <53µm (Fsa, silt-clay fraction). The evaluated variables were: stalk yield (Mg.ha-1); total nitrogen (Nt, kg.ha-1), nitrogen derived from fertilizer (NddF, kg.ha-1), and nitrogen derived from residues (NddR, kg.ha-1) in soil and plant; and total carbon in soil (C, Mg.ha-1). During all years, stalk yield and uptake nitrogen were higher (p<0.05) in the CQ than in the SQ system. Considering the quantity of residues that remained in the system and their Nt content, the estimated potential of N recycling for the system SQ was 65% of the Nt contained in the aboveground parts of the crop. For the CQ harvest system, the potential loss of N was estimated as 85% of N in the aboveground parts of the crop. In the cane-plant harvest, the recovery of NddF in the soil-plant system was of 46,9kg.ha-1 (63,0% were found in the aboveground part of the crop). In the following years, an exponential decrease of NddF recovered in the aboveground part of the plant was observed. In the SQ harvest system, the NddF recovered in the soil-plant system in the second year (first ratoon cane) was significantly higher (p<0.05) than in the CQ system. Approximately, 95% of NddR were immobilized in the soil, remaining in the system at the end of the crop of the fourth ratoon cane, four years after that it have been added. The contents of total carbon and nitrogen in the soil fractions presented growing values in the following order: Fsa>Fom>Fl. The fraction Fsa contained more than 70% of the total C and total N of the soil. The harvest system did not influence the soil carbon content neither his distribution in the fractions. At the fourth ratoon cane (2002), the SQ system presented values of Nt higher (p<0.05%) in Fl and Fom in the 0-15cm layer, and in Fom in the 30-50cm layer. The 15N-residues from the first crop cycle explain the higher content of 15N in Fl.
25
Chiaradia, Jonas Jacob. "Avaliação agronômica e fluxo de gases do efeito estufa a partir de solo tratado com resíduos e cultivado com mamona (Ricinus communis L.) em área de reforma de canavial." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/11/11140/tde-10032006-155625/.
Full textAbstract:
A aplicação de resíduos em solos agrícolas pode alterar significativamente a dinâmica do ciclo dos elementos no solo, conseqüentemente modificando sua fertilidade, a nutrição das plantas e os fluxos de gases do solo para a atmosfera. A possibilidade de produção de biocombustíveis a partir de óleos vegetais e com a atenção especial dada a cultura da mamona faz nesse momento com que o cultivo desta oleaginosa ressurja nacionalmente como cultura de interesse. Além disso, em áreas agrícolas próximas a grandes centros urbanos, a utilização agrícola de resíduos na agricultura é uma prática já empregada, porém ainda, sem o total conhecimento dos processos envolvidos em relação ao comportamento desses materiais no ambiente e seu real comportamento como fonte de nutrientes para as culturas. Em função do exposto, o presente trabalho foi realizado com o objetivo de avaliar os efeitos de três resíduos, contendo diferentes formas de N, na fertilidade do solo e nutrição mineral da mamona cultivada em área de reforma de canavial, bem como também quantificar os fluxos de gases do efeito estufa (CO2, CH4 e N2O) em função da aplicação de doses de um lodo de esgoto ou fertilização mineral no solo, antes do plantio da mamona. Assim, foram conduzidos dois experimentos a campo no ano agrícola de 2004-2005. No primeiro avaliou-se a contribuição de resíduos como fonte de N para a cultura da mamona e foi conduzido sob um Argissolo Vermelho-Amarelo distrófico. A dose de nitrogênio referencial foi de 75 kg ha-1 e as quantidades aplicadas de cada resíduo foram calculadas em função do conteúdo e disponibilidade do N nestes. Os dados obtidos mostram que os resíduos de origem orgânica (lodo de esgoto e Citrofer) constituíram-se numa fonte eficiente de N e para as doses equivalentes ou maiores que a referência, a produtividade da mamona foi igual ou superior a adubação mineral. Com relação a outros componentes de produção, o tamanho do racemo e nº de frutos para os tratamentos que receberam a aplicação de N via resíduos orgânicos ou a adubação mineral, não diferiram estatisticamente, mas foram superiores aos demais. O N foi o nutriente que mais limitou o desenvolvimento e produtividade da mamona. No segundo experimento avaliou-se a emissão dos gases CO2, CH4 e N2O na mesma área onde foi realizado o primeiro experimento, porém, foram avaliados os tratamentos que receberam adubação mineral e lodo de esgoto em três doses. Tanto a adição de lodo de esgoto como a adubação mineral alteraram os fluxos de CO2, N2O e CH4. Quando a quantidade de N aplicada via lodo de esgoto foi igual ao tratamento que recebeu adubação mineral, parece não haver diferenças entre as emissões de CO2 desses tratamentos. Para o N2O, quando se faz a comparação entre os tratamentos que foram concebidos para disponibilizar cerca de 75 kg N ha-1, observa-se que os valores de emissão de N2O na maioria das amostragens foram semelhantes. O tratamento que recebeu o dobro da dose de N via lodo de esgoto apresentou emissões de N2O superiores ao tratamento controle e adubação mineral. Com relação à emissão de metano para a atmosfera, não houve diferenças significativas entre os tratamentos.The application of residues in agricultural soils can significantly change the dynamic of the element cycles into the soil, changing consequently its fertility, the plant nutrition and the soil gas fluxes to the atmosphere. The possibility of bio-fuel production from vegetable oils and the special care given to the castor bean at this time, make interest to this crop to re-start its cultivation in all country. Beside that, agricultural area near big urban centers, the use of residues in crop production is common and it is already incorporated, but there is still lack of knowledge of the process involved in relation to the behavior of these residues in the environment and as a source of nutrients for the crops. Taken in consideration what was written above, the present work was made aiming to evaluate the effect of three residues having different forms of nitrogen in the soil fertility and mineral nutrition of castor bean cultivated in a reform area of sugar cane, and also to quantify the gas fluxes of greenhouse effect (CO2, CH4 and N2O) in relation to the applied dose of sewage sludge or mineral fertilization of the soil before the castor bean plantation. Two experiments were carried out in the field in the agricultural year of 2004-2005. In the first it was evaluated the residues contribution as nitrogen source to the castor bean crop and it was conducted under one Ultisol (Argisolo Vermelho Amarelo distrófico) soil. The reference dose for nitrogen was 75 Kg ha-1 and the applied quantities of each residue were calculated in function of the content and the availability of N into the residues. The data have shown that the residues of organic origin (sewage sludge and Citrofer) constitute in an efficient source of N and for the equivalent dose or grater than the reference dose, the castor bean productivity was similar or higher than the mineral fertilization. In relation to the other parameters of production, the size of raceme and the number of fruits for the treatments that received N application via organic residues or mineral fertilization, did not differ statistically, but they were higher than the other treatments. The N was the nutrient that limited more the development and the productivity of castor bean. In the second experiment, it was evaluated the CO2, CH4 and N2O gas emission in the same area of the first experiment, but with treatments that received mineral fertilization and sewage sludge in three doses. The sewage sludge and the mineral fertilization changed the gas flow of CO2, CH4 and N2O. When the applied quantity of N via sewage sludge was equal to the mineral fertilization treatment seems that there was no difference between the CO2 emissions. For the N2O, when it was compared the treatments responsible to fulfill about 75 Kg ha-1 of N, it was observed that the values of N2O emission were similar for the great part of samples. The treatment that received the double dose of N via sewage sludge presented N2O emission higher than the control and the mineral fertilization treatments. All the treatments presented no difference for the methane emission to the atmosphere.
26
Keeney, Andrea Brooke. "Effects of Potassium Source and Rate on Yield, Quality, and Leaf Chemistry of Dark and Burley Tobacco, and Residual Effects of Soil K Levels." UKnowledge, 2019. https://uknowledge.uky.edu/pss_etds/120.
Full textAbstract:
Field trials were conducted in 2016, 2017 and 2018 with dark fire-cured, dark air-cured, and burley tobacco at Princeton, Murray and Lexington Kentucky. Tobacco variety used in 2016 was a low converter (LC) variety, varieties used in 2017 and 2018 were LC and higher converter (HC) varieties. Potassium sources used at all locations and in all years were potassium sulfate (K2SO4) and potassium chloride (KCl). Application rates used at all locations and in all years were 93, 186, 279 kg K ha-1along with an untreated control that received no potassium. In all trials, tobacco that was treated with either potassium source yielded numerically higher than the untreated control. In seven out of 10 trials, LC varieties had a higher moisture content than HC varieties. Tobacco treated with KCl had higher chloride levels than tobacco treated with K2SO4.Quality grade index was similar for tobacco treated with KCl compared to tobacco treated with K2SO4. In all trials, tobacco treated with KCl had numerically lower Tobacco Specific Nitrosamines (TSNA) levels than tobacco treated with K2SO4. Reductions in TSNA levels were 30% lower in tobacco treated with KCl compared to tobacco treated with K2SO4.
27
Puta, Usanda. "Effects of genetically modified maize (MON810) and its residues on the functional diversity of microorganisms in two South African soils." Thesis, University of Fort Hare, 2011. http://hdl.handle.net/10353/419.
Full textAbstract:
Genetically modified (GM) crops are commercially cultivated worldwide but there are concerns on their possible negative impacts on soil biodiversity. A glasshouse study was conducted to determine effects of Bt maize residues on soil microbial diversity. Residues of Bt maize (PAN 6Q-308B) and non-Bt maize (PAN 6Q-121) were incorporated into the soil and corresponding maize seeds planted. The treatments were replicated three times. Fertilizer and water application were similar for both treatments. Rhizosphere and bulk soil was destructively sampled from each treatment and analyzed for microbial community level physiological profiles using Biolog plates with 31 different carbon substrates. Absorbance in the Biolog plates was recorded after 72 h of incubation at 20oC. Arbuscular mycorrhizal fungi spore counts were also determined. Field studies were conducted at the University of Free State and University of Fort Hare Research Farms to determine the effects of growing Bt maize on soil microbial diversity. One Bt maize cultivar (PAN6Q-308B) and non-Bt maize (PAN6Q-121) were grown in a paired experiment at University of Free State farm, while two Bt maize (DKC61-25B and PAN6Q-321B) and their near-isogenic non-Bt maize lines (DKC61-24 and PAN6777) were grown in a randomized complete block design with three replicates. Fertilization, weed control and water application, were similar for both Bt maize cultivars and their non-Bt maize counterparts. Rhizosphere soil samples were collected by uprooting whole plants and collecting the soil attached to the roots. The samples were analysed for microbial diversity and for arbuscular mycorrhizae fungal spore counts. Principal component analysis showed that soil microbial diversity was affected more by sampling time whereas genetic modification had minimal effects. Presence of residues also increased the diversity of microorganisms. Mycorrhizal fungal spores were not affected by the presence of Bt maize residues. Growing Bt maize had no effect on the soil microbial diversity in the rhizosphere.
28
Junior, José Geraldo de Abreu Sousa. "Decomposição de diferentes doses de palhada de cana-de-açúcar e seu efeito sobre o carbono do solo." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/64/64135/tde-19052015-144912/.
Full textAbstract:
O objetivo desta pesquisa foi avaliar a decomposição de diferentes quantidades iniciais de palhada de cana-de-açúcar depositadas sobre o solo, sob diferentes práticas de manejo e determinar o acúmulo de carbono orgânico total (COT) neste solo ao longo de três cortes da cana. Para tanto, foram instalados três ensaios em lavoura de cana-de-açúcar no município de Piracicaba. No experimento 1 foram depositadas na entrelinha da cultura, sobre o solo, diferentes quantidades de palhada (3,5; 7; 14 e 21 Mg ha-1) e mais dois tratamentos na dose de 14 Mg ha-1 ora incorporada ao solo e ora irrigada com vinhaça. A perda de matéria seca e a composição da palhada remanescente foi avaliada em seis momentos ao longo de um ano. No experimento 2, utilizando-se os mesmos tratamentos do experimento anterior, foram instalados lisímetros de tensão para coleta da solução do solo e determinação do carbono orgânico dissolvido (COD) em 0,20 e 0,50 m de profundidade. Para determinação do COT em função das diferentes doses de palhada depositadas sobre o mesmo ao longo de 3 cortes da cana-de-açúcar, instalou-se o Experimento 3. Para que fosse detectada a entrada de carbono (C) em função do aporte destas doses de palhada ao longo dos 3 anos, o solo original da entrelinha da cana-de-açúcar foi substituído por um solo de uma área adjacente de mesma classe, que não era cultivado com cana-de-açúcar ha pelo menos 25 anos, por isso com baixo delta 13C (?13C). Esta técnica isotópica foi utilizada para determinar e quantificar a origem das entradas do C no solo ao longo dos anos em que foram aplicados os tratamentos. Os resultados deste trabalho sugerem que após um ano da deposição da palhada no campo a decomposição de 65% das maiores doses de palhada (14 e 21 Mg ha-1), chegam a ser de 24 a 39% superiores às menores doses (7 e 3,5 Mg ha-1 respectivamente). A dose 14 Mg ha-1 quando incorporada acelera ainda mais este processo, resultando numa decomposição final de 86%. Já a irrigação com vinhaça não favoreceu este processo. Em relação à composição da palhada remanescente, os tratamentos 14 Mg ha-1 incorporado e 21 Mg ha-1 resultaram no aumento mais expressivo do índice lignocelulósico. O monitoramento do COD a 0,5 m de profundidade durante 120 dias na estação chuvosa detectou a presença de C somente nos 45 dias iniciais da decomposição da palhada. O percentual de COD disponibilizado pela palhada foi inversamente proporcional a taxa de decomposição. O acompanhamento do acúmulo de C no solo ao longo de 3 anos de aporte de diferentes quantidades de palhada da cana-de-açúcar, mostrou um aumento significativo de 80% e 97% nas concentrações de COT nos 2,5 cm superficiais do solo onde as doses de 14 e 21 Mg ha-1 de palhada, haviam sido aplicadas, respectivamenteThe objective of this research was to evaluate the decomposition of different initial quantities of sugarcane trash placed onto the soil under different management practices and determine the total organic carbon (TOC) accumulation in this soil over three years sugarcane cycle. Therefore, three experiments were installed in sugarcane area at Piracicaba. In experiment 1, different amounts of sugarcane trash (3.5, 7; 14 and 21 Mg ha-1) were placed between the rows, above the soil. Two additional treatments were installed with 14 Mg ha-1 dose: or incorporated into the soil or irrigated with vinasse. The dry matter losses and the composition of remaining sugarcane trash were evaluated six times over a year. In experiment 2, using the same previous treatments, lysimeters were installed to collect soil solution and to determine dissolved organic carbon (DOC) at 0.20 and 0.50 m depth. Experiment 3 was settled to determine the Carbon (C) derived from the different doses of deposited sugarcane trash. The C input derived from the straw doses after three years was detected replacing the original soil at sugarcane inter-row by a soil from an adjacent area not cultivated with sugarcane for at least 25 years, presenting a low delta 13C (?13C). This isotope technique was used to determine and quantify the origin of soil C input, after the treatments applied over the years. Results of this study suggest that one year after the deposition of the trash on soil, the higher doses (14 and 21 Mg ha-1) lost about 65% dry matter, a rate up to 24-39% higher than the lower doses (7 and 3.5 Mg ha-1 respectively). The 14 Mg ha-1 dose, when incorporated, accelerated this process, resulting in a total breakdown of 86%. However, vinasse irrigation did not favored this process. Regarding the composition of the remaining trash, the treatments of 14 Mg ha-1 incorporated to soil and the 21 Mg ha-1 resulted in the most significant increase in lignocellulosic index. The DOC monitoring at 0.5 m depth over 120 days in the rainy season detected the presence of C only during the initial 45 days of straw decomposition. The percentage of DOC available from sugarcane trash was inversely proportional to the decomposition rate. Carbon accumulation in the soil over 3 years, related to different amounts of sugarcane trash, showed a significant increase of 80% to 97% in TOC concentrations in the upper 2.5cm soil layer where the doses of 14 and 21 Mg ha-1 of trash were applied, respectively
29
Penick, William Frazier. "Influence of Transplanter Modification and Previous Crop on the Production of No-Till Dark Tobacco." TopSCHOLAR®, 2013. http://digitalcommons.wku.edu/theses/1257.
Full textAbstract:
Dark tobacco (Nicotiana tabacum L.) has historically been produced usingconventional tillage practices. Soil is cultivated multiple times throughout a growing season leading to an increased incidence of soil erosion. No-till systems have been growing in popularity with the advent of new technology that has enabled the practice to be performed effectively and efficiently. With the recent expansion of no-till practices throughout the agricultural community, many crops have had success in producing comparable yields while reducing input costs and saving soil resources. For this experiment, a traditional tobacco transplanter was modified for use in a no-till environment. All modifications were fabricated without using specialty tools and made possible to be removed if desired or necessary. Frame extensions were designed and built to accommodate row cleaners and coulters. Tillage shanks were also added to aid in optimal furrow formation. Double-disc opening shoes replaced the original round point shoes and the curved edges of the rear drive wheels were removed, creating a flat surface to increase soil contact. Experimental no-till plots in fescue sod and soybean chaff residues were conducted alongside conventional tillage plots at the Western Kentucky University Agricultural Research and Education Complex in summer 2011. Five treatments, one conventionally tilled (Conv) and four no-till, were replicated three times within a randomized complete block design and used to determine the efficacy of transplanter modifications (consistency of depth, furrow closure, observed plant damage), survival of the transplants, and the amount of residue displacement. The four no-till treatments utilized different combinations including: coulter, row cleaner and shank (CRS), row cleaner and shank (RS), coulter and shank (CS), and shank only (S). These treatments demonstrated the functionality of each combination in comparison to conventional treatments. No treatment performed equally well in both residue locations. Plots in fescue residue utilizing a combination of coulter, row cleaner, shank (CRS), exhibited the lowest amount of root exposure, highest survival rate, and comparable cured weight when compared to conventionally tilled treatments. In soybean residue plots, the treatment operating with row cleaners and shanks (RS) had equivalent amounts of furrow closure to conventionally tilled plots. Pairing specific modification combinations with previous crop residue can provide furrow closure, transplant survival, and cured yield equivalent to conventionally tilled dark tobacco.
30
Cochran, Michele A. "Effect of land application of fluidized-bed combustion residue on soil and plant characteristics of reclaimed surface-mined pastures, performance and mineral status of grazing steers and nutrient balance by sheep fed the forage." Thesis, Virginia Tech, 1988. http://hdl.handle.net/10919/43389.
Full text
31
Santos, Carlos Antonio Barreto dos. "Cons?rcios de esp?cies de cobertura de solo para aduba??o verde antecedendo ao cultivo de milho e repolho sob manejo org?nico." Universidade Federal Rural do Rio de Janeiro, 2009. https://tede.ufrrj.br/jspui/handle/tede/535.
Full textAbstract:
Made available in DSpace on 2016-04-28T14:58:38Z (GMT). No. of bitstreams: 1
2009 - Carlos Antonio Barreto dos Santos.pdf: 6633158 bytes, checksum: 82ad5fa6564f31d7aa7587f533bf91ed (MD5)
Previous issue date: 2009-03-03Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior
Four plant species, intercropped or not, were evaluates in the State of Rio de Janeiro for Green manuring and soil covering prior to corn or cabbage crops. Such crops were submitted to a no-tillage and organic farming system. The study relating to corn was carried out in Baixada Fluminense (Serop?dica) at 33 m above sea level, whereas the cabbage experiment was the located in the South-Central Region (Paty do Alferes) at 680m. In bony experiments a randomized block design was employed with 12 treatments and four replicates. The species lazed for soil covering were: Crotalaria juncea (C), sorghum Sorghum bicolor (S), sunflower Heliantus annus (G) and castor bean Ricinus communis (M). Treatments involving such soil covering species corresponded to their monocrops ad the following intercrops: C+G, C+S, C+M, C+G+S, C+S+M and C+G+S+M. The control treatment consisted of fallow plots whove spontaneous vegetations was cut down on the day subsequent corn and cabbage were planted. In Baixada Fluminense, the previous intercrops favored epigeous edafic fauna diversity compared to fallow, either during vegetative cycle or after cutting except for castor bean monocrop, all treatments led to reduced need reinfestation in comparison to fallow plots. Corn yield (immature ears) was higher after monocrops of the soil covering species and also after fallow. Crotalaria showed in outstanding potential as green manure considering that organic suplementar corn fertilizing were proceeded only in plots previously cultivated to such legume species. The greatest cumulative e amount of above-ground biomass resulted from crotalaria monocrop probably contributing to a superior corn yield. In the South-Central field experiment the highest values for biomass productin were again obtained from crotalaria monocrop, its intercrops with each of the other soil covering species (C+G, C+S and C+M), and the triple intercrop with sorghum plus castor bean (C+S+M). Decomposition rates for the cut down plant residues in situ differed between intercrops and monocrops. Cabbage yield was as cell favoured by previous crotalaria and its intercrops, with exception of the intercrop in which all four plant species participated. Results have demonstrated the adequacy of crotalaria for rotational system with commercial crops under organic management. The experiments otherwise indicated that combining the legume with other soil covering species may lead to additional advantages in terms of crop residues persistence on soil surface and ed?fica fauna stimulation.
Avaliaram-se, no Estado do Rio de Janeiro, quatro esp?cies bot?nicas, consorciadas ou n?o, para aduba??o verde e cobertura do solo, antecedendo as culturas de milho verde e repolho. Estas culturas foram implantadas em sistema plantio direto e submetidas ao manejo org?nico. O estudo com o milho verde foi conduzido na Baixada Fluminense (Serop?dica) a 33 m de altitude enquanto o estudo com o repolho teve lugar na regi?o Centro Sul (Paty do Alferes) a 680m. Em ambos os experimentos, empregouse o delineamento de blocos casualizados, envolvendo 12 tratamentos com quatro repeti??es. As esp?cies de cobertura do solo utilizadas foram: Crotalaria juncea (C), girassol Heliantus annus (G), sorgo Sorghum bicolor (S) e mamoneira Ricinus communis (M). Os tratamentos relativos ?s esp?cies de cobertura corresponderam aos respectivos monocultivos e aos cons?rcios: C+G, C+S, C+M, C+G+S, C+G+M, C+S+M e C+G+S+M. O tratamento controle foi representado pelas parcelas que permaneceram em pousio, cuja vegeta??o espont?nea foi ro?ada por ocasi?o dos plantios subsequentes de milho ou repolho. Nas condi??es da baixada fluminense, os cons?rcios favoreceram a diversidade da fauna ed?fica ep?gea, quando comparados com o pousio, tanto ao longo do ciclo vegetativo das esp?cies de cobertura quanto ap?s o corte. Com exce??o do monocultivo de mamoneira, os demais tratamentos provocaram redu??o dos n?veis de reinfesta??o de ervas espont?neas, relativamente ao pousio. A produtividade do milho em espigas verdes foi superior quando em sucess?o aos monocultivos das esp?cies de cobertura e pousio. A crotal?ria revelou destacado potencial como adubo verde, tendo em vista que somente nas parcelas onde foi previamente cultivada o milho n?o recebeu fertiliza??o org?nica suplementar. A maior quantidade acumulada de biomassa a?rea seca tamb?m resultou do monocultivo de leguminosa, o que provavelmente contribuiu para o rendimento superior do milho. No ensaio conduzido na regi?o Centro Sul, os valores mais elevados de biomassa produzida foram tamb?m obtidos a partir da crotal?ria em monocultivo, de seu cultivo consorciado com cada uma das outras plantas de cobertura (C+G, C+S e C+M) ou do triplo cons?rcio com sorgo e mamoneira (C+S+M). As taxas de decomposi??o in situ dos res?duos vegetais ro?ados distinguiram os cons?rcios dos monocultivos. Em termos de produtividade, o repolho foi beneficiado pelo pr?-cultivo de crotal?ria e seus cons?rcios, com exce??o daquele do qual participaram todas as quatro plantas de cobertura. Os resultados demonstraram adequa??o da Crotalaria juncea para sistemas rotacionados com culturas, de interesse comercial sob manejo org?nico. Indicaram, todavia, que combina??es desta leguminosa com outras esp?cies nos pr?-cultivos podem acarretar vantagens adicionais, ligadas ? persist?ncia da palhada distribu?da na superf?cie do solo, a partir do corte da biomassa a?rea, e ? diversidade da fauna ed?fica ep?gea.
32
Carvalho, Stella Pacheco Lombardi de. "Resíduos de deltametrina e de carbaril em dois sistemas de condução da cultura de tomate estaqueado (Lycopersicon esculentum Mill) e sua eficiência no controle da broca-pequena-do-fruto Neoleucinodes elegantalis (Guenée, 1854) (Lepidoptera: Crambidae)." Universidade de São Paulo, 2004. http://www.teses.usp.br/teses/disponiveis/11/11146/tde-22092004-143434/.
Full textAbstract:
O objetivo deste estudo foi avaliar os inseticidas deltametrina e carbaril, de modo a abranger seus resíduos em dois sistemas de condução da cultura de tomate estaqueado (linha dupla, plantio comercial e linha simples, plantio experimental) e sua eficiência no controle da broca-pequena-do-fruto, a determinação dos resíduos nos substratos: frutos (visando à proteção à saúde pública), folhas e solo (como uma possível fonte de contaminação ambiental), a comparação dos níveis de resíduos encontrados nesses diferentes sistemas de condução, o controle obtido com os dois inseticidas e sistemas de condução e a comparação dos níveis de resíduos dos frutos com os LMRs (Limites Máximo de Resíduo) e intervalo de segurança estabelecidos pela legislação brasileira. O experimento foi conduzido no Município de Piedade, no Estado de São Paulo, Brasil. Consistiu em cinco tratamentos: (1) nove aplicações de deltametrina (Decis 25 CE) no plantio linha simples, (2) nove aplicações de carbarill (Sevin 480 SC) no plantio linha simples, (3) nove aplicações de deltametrina (Decis 25 CE) em linha dupla, (4) nove aplicações de carbaril (Sevin 480 SC) no plantio linha dupla e (5) controle. A primeira aplicação foi feita no início da fase de maturação do fruto e as seguintes em intervalos subseqüentes de 7 dias. As amostras de frutos foram colhidas com (-1), zero, 3, 5 e 10 dias após a última aplicação. As amostras de folha e solo foram coletadas com (-1), zero, 1, 3, 10 e 20 dias após a última aplicação. O método analítico consistiu na extração dos resíduos com acetato de etila, limpeza dos extratos em cromatografia de permeação em gel (GPC), e determinação quantitativa em cromatógrafo de gás equipado com detector de captura de elétrons (GLC/ECD) (deltametrina) e em cromatógrafo de gás equipado com detector seletivo de massas (GLC/MSD). Os resultados mostraram que os resíduos de deltametrina nos frutos no plantio comercial estavam abaixo de seu LMR ao final do intervalo de segurança; o mesmo não ocorreu com o carbaril que nos dois sistemas de condução, apresentou resíduos superiores ao seu LMR. Os resíduos maiores foram encontrados nas folhas, para ambos os inseticidas, constituindo assim, estas, uma possível fonte de contaminação ambiental. Os resíduos encontrados no solo foram baixos, no caso da deltametrina se aproximaram dos valores encontrados para o fruto e os de carbaril foram ainda menores que os do fruto, mostrando um baixo escorrimento da calda de saturação e conseqüentemente, um baixo potencial de contaminação do solo. O plantio experimental (linha simples) apresentou resíduos sempre maiores que o plantio comercial (linha dupla), sendo, em conseqüência, melhor o controle da praga nesses tratamentos.The objective of this study was to evaluate the insecticides deltamethrin and carbaryl, in order to study their residues, in two cultivation systems of staked tomato crop: experimental cultivation (single line) and commercial cultivation (double line) and their efficiency in the control of the fruit small borer, Neouleucinodes elegantalis (Guenée, 1854) (Lepidoptera: Crambidae), the determination of the residues in fruits (aiming the protection of public health), leaves and soil (like a possible source of environmental contamination), the comparison of residues found in these two different systems of cultivation, the control achieved with both insecticides and systems of cultivation and the comparison of the residues in fruits with the MRLs (Maximum Residue Levels) and safety intervals established by Brazilian legislation. The experiment was conducted Piedade County in the State of São Paulo, Brazil. It consisted of five treatments: (1) nine applications of deltamethrin (Decis 25 CE) in single line, (2) nine applications of carbaryl (Sevin 480 SC) in single line, (3) nine applications of deltamethrin (Decis 25 CE) in double line, (4) nine applications of carbaryl (Sevin 480 SC) in double line and (5) control. The first application was made at the begining of the fruit maturation stage, and the following ones in 7 days period scheduled. Fruit samples were collected one day before the last application (-1 day) and zero, 3, 5 and 10 days after the last application. Leaf and soil samples were collected one day before the last application (-1 day) and zero, 1, 3, 10 and 20 days after the last application. The analytical method consisted by extraction of residues with ethyl acetate, clean-up of the extracts by gel permeation chromatograph (GPC), and quantitative determination by gas chromatograph equipped with electron capture detector (GLC/ECD) (deltamethrin) and by gas chromatograph equipped with mass selective detector (GLC/MSD). The results showed that deltamethrin residues in fruits from commercial cultivation system (double line) were below MRL at the end of safety interval; as for carbaril residues they were above MRL in fruits from both cultivation systems. Higher residues were found on leaves, for both insecticides, being considered this as a possible source of environmental contamination. Soil residues were lower; as for deltamethrin the levels were similar to fruit, but for carbaril they were lower in as compared to fruits showing low drift from the saturated foliage and consequently, low potential of soil contamination. The experimental cultivation system (single line) always showed higher residue levels for both insecticides than the commercial one (double line), being, in consequence, better the insect pest control in these treatments.
33
Green, Colleen H. "Water treatment residual and vegetative filter strip effects on phosphorus transport dynamics." Access citation, abstract and download form; downloadable file 7.55 Mb, 2004. http://wwwlib.umi.com/dissertations/fullcit/3131673.
Full text
34
Blomgren, Axel. "Influence of logging residues on MeHg accumulation in soil." Thesis, KTH, Hållbar utveckling, miljövetenskap och teknik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-234263.
Full textAbstract:
Forestry has been found to increase the accumulation of methyl mercury (MeHg), a highly neurotoxic compound, in forest soils. However, little is known about how forestry influences catchment processes that governs the mercury (Hg) methylation process. Logging residues are used in harvested catchments in stick roads to reduce soil disturbances caused by forestry machinery. Logging residues left on site after harvest have been suggested to act as a source of high-quality organic matter that stimulates the activity of the microorganisms that carry out the methylation of Hg. In addition, logging residues might influence the activity and abundance of methylating bacteria by reducing the temperature fluctuations in soils below residues and by increasing the soil moisture content. To evaluate the impact of logging residues on the accumulation of MeHg, an experimental field study was carried out in three sites, one in Uppland and two in Västerbotten. The concentration of MeHg was compared between soils covered with residues and soils without residues, and between the lower and upper parts residue piles. Logging residues were not found to influence the levels of MeHg in soils. However, an increased accumulation of MeHg was found in the lower part of residue piles. The accumulation of MeHg in the lower parts was accompanied by a reduced temperature amplitude and an increased water content compared to the upper part of the piles. The increased formation of MeHg might have been mediated by an increased water content in the lower part of the residue piles, possibly by increasing the abundance and activity of Hgmethylating microorganisms due to suboxic/anoxic conditions within biofilms around decomposing needles. The dissolved organic matter composition in soil water differed in soils below residues compared to without residues, but the organic matter signature in soil water under residues was not found to be compliant with an elevated mercury methylation rate. As MeHg accumulated in the lower part of residue piles could become mobilized and transferred to surface water, the suitability of using logging residues in stick roads depends on the location within the catchment. The removal of logging residues could prevent the potential mobilization of MeHg from residue piles. Though, as soil disturbances may cause an increased Hg methylation rate and mediate MeHg export to surface waters, other form of protection, e.g. logging mats, should be used if logging residues are not used to protect soils.Mänsklig aktivitet har lett till förhöjda halter av kvicksilver (Hg) i atmosfären. Genom långväga transport och deposition har detta orsakat förhöjda halter i svensk natur. Den huvudsakliga exponeringsvägen av Hg för människan sker genom konsumtion av fisk. Halterna av Hg i svensk insjöfisk överstiger EU:s gränsvärden för god kemisk status samt Världshälsoorganisationens riktlinjer för konsumtion i majoriteten av svenska vatten. Ackumuleringen av Hg i biota sker främst i form av metylkvicksilver (MeHg) som är starkt neurotoxiskt. Avverkning av skog tros bidra till en ökad bildning av MeHg i skogsmark genom att skapa miljöer som gynnar etableringen och aktiviteten av de mikroorganismer som omvandlar icke-organiskt kvicksilver (Hg(II)) till organiskt kvicksilver (MeHg). Dessutom kan skogsbruk bidra till en ökad export av MeHg till följd av ändrade hydrologiska förhållanden samt markskador. En ökad bildning av MeHg är oönskad då mobilisering sedermera kan ske till vattendrag där MeHg kan ackumuleras i akvatisk biota. Dock är kunskapen om hur skogsbruk påverkar specifika processer som är av betydelse för metyleringen av Hg begränsad. Inom skogsbruk används avverkningsrester, bestående av till exempel grenar och toppar, i rishögar för att skydda marken mot körskador. Avverkningsrester som lämnas kvar på området efter avverkning tros bidra till en ökad metylering genom att utgöra en källa av högkvalitativt organiskt material vilket kan stimulera bakteriell aktivitet. Dessutom kan avverkningsrester bidra till en ökad metylering av Hg genom att minska temperaturfluktuationerna i mark täckt med ris samt öka markens vattenhalt, vilket kan bidra till en ökad etablering samt att stimulera aktiviteten av Hg-metylerande mikroorganismer. För att utvärdera effekten av avverkningsrester på ackumuleringen av MeHg genomfördes en experimentell fältstudie där koncentrationen av MeHg jämfördes i mark täckt med ris och mark utan ris. Dessutom undersöktes huruvida en ökad metylering kan ske i den nedre delen av riset, vilket skulle kunna möjliggöras av bakterier i biofilmer kring ris under nedbrytning. Koncentrationen MeHg var högre i den nedre delen av rishögarna jämfört med den övre delen. I den nedre delen av riset var temperaturfluktuationerna lägre och vattenhalten högre än i den övre delen av riset. Ackumuleringen av MeHg kan ha skett via biofilmer i de nedre delarna av riset, där tillgången till hög kvalitativt organiskt material samt mer syrefria förhållanden kan ha gynnat etableringen och aktiviteten av de bakterier som utför metyleringen av Hg. Däremot hade typen av marktäcke, dvs mark täckt med ris och mark utan ris, inte någon påverkan på metyleringen av Hg. Karaktären av organiskt material i markvatten skiljde sig mellan typ av marktäcke, men visar inte på att avverkningsrester utgör en källa av högkvalitativt organiskt material. Vattenhalten i mark under rishögar skiljde sig inte jämfört med mark utan ris, men temperaturen var lägre med mindre variation i mark under rishögar. Därmed visar resultatet på att avverkningsrester kan bidra till en ökad bildning av MeHg. En potentiell mobilisering av MeHg som bildats i rishögarna skulle därför kunna bidra till en ökad export av MeHg från avverkade områden. Användningen av avverkningsrester, för att skydda marken vid körning med skogsmaskiner, anses ändå vara fördelaktig för att minimera utläckage av MeHg. Körskador kan skapa stående vattensamlingar där MeHg kan bildas samt kompaktera mark och skapa snabba ytliga flödesvägar i området. Däremot tyder resultatet på att användningen bör ske med hänsyn till att förhindra eventuell transport av MeHg till vattendrag. Ifall avverkningsrester inte används för att motverka markskador bör ett substitut användas, exempelvis stock-mattor, då körskador kan bidra till en ökad metylering och mobilisering av MeHg. Dock saknas kunskap om eventuell mobilisering av MeHg från rishögar till vattendrag och detta bör utvärderas i framtida studier.
35
Jackson, Andrew William. "Analysis of soil chemical residues and other soil factors associated with past human activity." Thesis, University of Bristol, 2001. http://hdl.handle.net/1983/2f03f40f-c71c-46bd-9078-05fd07efd027.
Full text
36
Scharfy, Deborah. "Exotic plant invasions : importance of functional traits for soil characteristics and plant-soil feedback /." [S.l.] : [s.n.], 2009. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=18308.
Full text
37
McGouran, Joanna. "Probing sugar-plant-soil signalling." Thesis, University of Oxford, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.526091.
Full text
38
Heppell, James. "Optimising plant and soil management." Thesis, University of Southampton, 2014. https://eprints.soton.ac.uk/373886/.
Full textAbstract:
This thesis is an accumulation of work regarding the role of phosphorus (P) and water in soils in relation to crop growth and food production. We use a multiscale modelling approach to initially capture the interactions of soil and water on a single cylindrical root and further expand to a growing root structure. Moreover, we have a multi-physics problem involving fluid dynamics of water uptake in plants, and reactive solute transport in the soil for plant P uptake. We use detailed climate data and the super computer at the University of Southampton (Iridis 4) to parameterise our models. These facilities allow us to analyse the root structure as well as P and water in the soil in great detail. The collaboration of mathematics, biology and operational research makes it possible to complete this project. The analytical models recently developed within our group have shown to agree remarkably well with full 3D simulation models. These analytical models help provide the structure for the models used within this thesis and will for the first time enable us to start using optimisation techniques to find the optimal conditions for increasing plant P uptake efficiency. By using mathematical models to predict plant P and water uptake within the soil, we have addressed a number of questions surrounding the optimal plant root structure for P accumulation, and the survival of crops in a low P environment. In addition, we were able to predict the behaviour of water in the soil over the course of a full year. And finally, utilising all the above, we have outlined the optimal fertiliser and soil management strategy.
39
Odlare, Monica. "Organic residues - a resource for arable soils /." Uppsala : Dept. of Microbiology, Swedish University of Agricultural Sciences, 2005. http://epsilon.slu.se/200571.pdf.
Full text
40
Heap, John. "Increasing Medicago resistance to soil residues of ALS-inhibiting herbicides." Adelaide, Sth. Aust, 2000. http://hdl.handle.net/2440/19842.
Full text
41
Karpouzas, Dimitrios. "Aspects of the enhanced bio-degradation of Carbofuran and Ethoprophos in soil." Thesis, University of Reading, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.298757.
Full text
42
Schradin, Kelly Dawn. "The role of plant-soil feedback in exotic plant invasion: soil type, biotic or abiotic factors?" Wright State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=wright1334073581.
Full text
43
Mapfumo, Emmanuel. "Soil and plant response to compaction." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq23028.pdf.
Full text
44
Löfkvist, John. "Modifying soil structure using plant roots /." Uppsala : Dept. of Soil Sciences, Swedish University of Agricultural Sciences, 2005. http://epsilon.slu.se/200560.pdf.
Full text
45
Reinhardt, Theresa Ann. "Susceptible Crop Response to Soil Residues and Foliar Exposure of Dicamba." Thesis, North Dakota State University, 2016. https://hdl.handle.net/10365/28014.
Full textAbstract:
Dry bean, soybean, sugarbeet, and sunflower were tested for tolerance to dicamba residue in soil. Visible injury was seen on dry bean and soybean depending on location, but yield differences were not present. Increasing rates of glyphosate and dicamba caused injury to dry edible bean; however, final bean weight only differed from the nontreated when 18 g ha-1 dicamba was included. Dicamba applied at 1.8 g ha-1 caused a consistent delay in physiological maturity. Dicamba concentration in plants did not predict yield loss. Across the four market classes in the field, dicamba caused yield loss, but glyphosate did not. Effects of the herbicide on yield was the same in each market class.Monsanto and Northarvest Bean Growers
46
Hill, Brian Edward. "Soil sample handling for routine analysis of plant-available soil potassium." [Ames, Iowa : Iowa State University], 2009. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1468092.
Full text
47
Newell, Christopher Jack. "In vitro soil-less (IVS) rooting medium." Newell, Christopher Jack (2006) In vitro soil-less (IVS) rooting medium. PhD thesis, Murdoch University, 2006. http://researchrepository.murdoch.edu.au/227/.
Full textAbstract:
The principle hypothesis of this thesis is that hypoxia, in agar-based media, compromises rooting in vitro. From a practical point of view this is important because most plant tissue culture activities require the material to be successfully acclimatised in a nursery environment. Compromised rooting often results in excessive losses at this stage which are costly and inconvenient. In addition, many plants with commercial and/or scientific interest remain unavailable as they are not able to be rooted and acclimatised reliably. The use of agar as a rooting medium has limited the capacity of plant tissue culture to clonally propagate many plants.
The thesis begins by demonstrating how poorly some plants respond to agar rooting media. Juvenile Chamelaucium hybrid microcuttings were pulsed with IBA 40 mcg M and then placed for 3 weeks on either M1 (1/2 MS) or aerated in vitro soil-less substrate (IVS) (Chapter 2). IVS had 42-82% rooting at the end of Stage 3 compared with 0-1% in agar. Shoot survival for IVS-rooted microcuttings was significantly greater than M1-rooted shoots. Pulsed shoots placed in IVS showed root primordia after 7 days. In contrast, shoots placed in agar showed no root primordia after 21 days and formed callus but did not root when subsequently placed in IVS for a further 4 weeks. The agar medium almost totally and permanently inhibited the capacity of competent shoots to form root primordia and roots.
The effectiveness of different types of aerated and non-aerated media, including IVS, were tested to validate the hypothesis (Chapter 3). Microcuttings from shoot cultures of two Australian plants Grevillea thelemanniana and Verticordia plumosa x Chamelaucium uncinatum were pulsed for 7 days on a high auxin (40 mcg M IBA), agar-solidified medium in the dark. Rooting of the microcuttings was then compared on five experimental substrates: a) standard agar M1 medium (1/2 MS, no hormones, 8 g agar L-1), b) porous-agar medium (1/2 MS, no hormones, 30 g agar L-1, solidified then blended to provide aeration), c) white sand wet with liquid M1, d) white sand with M1 medium containing agar, and e) IVS. A separate experiment involved flushing the IVS soil profile with low or normal oxygen. Low and variable rooting percentages were recorded on the controls on M1 medium. Root induction and average total root length per microcutting at final harvest were significantly higher using the porous media including IVS, blended agar or white sand. The M1 medium and the addition of M1 medium to sand suppressed the percentage rooting and elongation. Flushing the IVS rooting medium with low oxygen also suppressed rooting. The experiments showed that increasing the air-filled porosity of the rooting medium has a positive effect on rooting and this is most likely due to the increased oxygen at the base of the microcutting. The role of ethylene, and the sugar and nutrients in M1 were not investigated.
The efficacy of the IVS protocol on a range of Australian herbaceous and woody species was investigated to determine whether the observed benefits were generic or plant specific (Chapter 4). Improved rooting in IVS compared to agar was shown for 28 Australian species and genotypes from the families Liliaceae, Haemodoraceae, Myrtaceae, Thymelaeaceae, Proteaceae, Goodeniaceae and Rutaceae. Twenty-seven of the 28 species rooted in IVS medium at equal or better rates than in M1. In three cases - Actinodium cunninghamii, one of the Pimelea physodes genotypes and one of the Eriostemon australasius genotypes - shoots did not root in M1 but showed good root development in IVS medium. With few exceptions average root length and number in microcuttings rooted in IVS was superior to those in agar medium.
To further test the resilience of the hypothesis, it was tested on nodal microcuttings of lentil which are recalcitrant to root in vitro (Chapter 5). The veracity of a published conclusion that inverted lentil microcuttings (with their base in the air) root better because of their altered polarity was also examined. It was found that, as is the case for many species, roots initiated and grew only at the proximal end of the microcutting regardless of its orientation. When the proximal end was in agar (a hypoxic environment) the rooting percentage was low (9-25%) even when the orientation of the microcutting was altered by inverting the culture tube. In contrast, when the proximal end of the microcutting was in an aerobic environment (from the shoot being placed upside down in agar medium or placed normally or upside down in an aerated medium) rooting percentages were higher (62-100%).
Given that Stage 2 microcuttings are prepared with the objective to root and acclimatise them to nursery conditions, the duration of this activity becomes important as it can impact on plant quality and costs. The pulsing protocol and the length of time that Stage 3 cultures remain in the culture room during the rooting phase is a component of the unit cost of production of each rooted microcutting. Initially a 7-day IBA pulse was used after which the pulsed microcuttings were transferred to IVS to root. Chapter 6 shows that the pulsing period can be shortened to one day or replaced with a single auxin dip while still achieving high rooting percentages and maintaining plant quality. These materials handling improvements go some way to realising the logistical benefits of ex vitro rooting but without compromising the positive influences of hygiene and a stable environment of the in vitro environment.
48
Diggle, Rebecca. "Regulatory science and uncertainty in the risk assessment of pesticide residues." Thesis, University of Nottingham, 2010. http://eprints.nottingham.ac.uk/11451/.
Full textAbstract:
In this thesis I examine how the scientific advisory system in England and Wales has responded to concerns about the risks of pesticide residues in food and demands for wider engagement in the formulation of advice. Specifically, I explore how the Advisory Committee on Pesticides (ACP) frames scientific uncertainties in risk assessment, and why some bodies outside and within government are critical of the ACP’s approach that is centred in the conventional single-chemical, high-dose-response paradigm of toxicology. Although some of these challenges date back to the early history of pesticide regulation in England and Wales, the emergence of scientific research employing different methods to assess the effects of chemical mixtures and chronic low-level exposure has stimulated new concerns about the risks posed by pesticide residues for human health. Using semi-structured interviews and documentary analysis, a key finding is that concerns about low-level exposure to chemical mixtures have been persistently bracketed in official advice as insufficient for changing current advice and regulation. Drawing from literature in science and technology studies, I account for this finding in three ways. First, it is perceived that change is unnecessary since established methods of pesticide risk assessment represent an exemplar for other domains. Secondly, evidence selection by the ACP and related committees is shaped by regulatory guidelines which aim to provide standardisation and quality assurance, but also constrain judgements about which risk assessment studies are considered admissible. Thirdly, fundamentally different notions are at play in terms of what constitutes legitimate expertise and who should embody it, leading to tensions within government as well as between the ACP and NGOs. These limit the impact of post-BSE attempts to make the role of scientific advice in policy-making more participatory and ‘evidence-based’, and the capacity to introduce new paradigms of chemical risk assessment in the pesticide advisory process.
49
Ess, Daniel R. "Cover crop residue effects on machine-induced soil compaction." Diss., This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-06062008-164819/.
Full text
50
Wong, Siu-wai. "Plant selection for revegetation projects in Hong Kong." Click to view the E-thesis via HKUTO, 1992. http://sunzi.lib.hku.hk/hkuto/record/B43893442.
Full text