Dissertations / Theses on the topic 'Soybean – Losses'

Soybean, Glycine max (L.) Merr., is planted across a vast amount of land in the Mid-Southern U.S. (Arkansas, Louisiana, Mississippi, and Tennessee), and yield responses to defoliation can vary. Experiments were conducted during 2015-2017 evaluating how soybean yield responds to multiple and continuous defoliation, as well as planting date and plant population. Multiple defoliation events were evaluated by defoliating soybean at varying levels at V3, V6, and both growth stages. There was no interaction between defoliation occurring at V3 and V6 growth stages, indicating that the impact of each defoliation event was independent of the other. The effect of continuous defoliation was evaluated by defoliating soybean weekly, beginning at V2. Defoliation continued throughout the vegetative growth stages or throughout the entire growing season, and was compared to the same defoliation level occurring one time at R3. Continuous defoliation during vegetative growth stages only, did not reduce yield at any of the levels tested. Defoliation occurring throughout the growing season reduced yields more than a one-time defoliation event at R3, but only when defoliation levels exceeded the 20% defoliation threshold. This indicates that thresholds do not need to be modified to account for multiple or continuous defoliation. To evaluate the effect of planting date on yield loss from defoliation, soybean was planted at six planting dates beginning in early-April and continuing through mid-June. Each planting date included a defoliated treatment and an undefoliated control. It was determined that later planted soybean lose a greater amount of yield than earlier planted. Higher yielding soybean also lost more yield than lower yielding soybean at every planting date until Mid-June. It was concluded that late planted soybeans could benefit from a lower treatment threshold. The effect of plant population on yield loss from defoliation was evaluated by planting soybean at five populations ranging from 123,500 seeds/ha to 420,070 seeds/ha. A undefoliated control and a defoliated treatment was included for each plant population. Defoliation significantly reduced yields only where final plant populations were lower than 192,800 plants/ha. This indicates that fields with substandard plant populations are more susceptible to yield loss from defoliating pests.

Target spot is a foliar disease of soybean that can produce yield losses. The disease has recently become a concern due to increasing intensity of its epidemics in the main soybean growing countries (USA, Brazil and Argentina). The goals of this study were to i) estimate the target spot control efficiency and yield response of labeled fungicides for the main soybean growing region of Brazil and identify factors affecting their performance; ii) characterize the relationship between target spot severity and soybean yield using meta-analytic techniques, and to identify patterns which allow understanding the heterogeneity in the relationship; iii) to explore the variability of genetic resistance of cultivars and verify the less time-consuming methodology for doing it; iv) explore the pathogen-host interaction effects on the epidemic development; v) compare the sensitiveness of the canopy strata position injured by C. cassiicola to reduce grain yield. Fungicides containing fluxapyroxad + pyraclostrobin were the most efficient ones to control target spot, with control levels of 75% and their yield response depended on the disease pressure (DP, DPLow < 35% target spot severity at untreated checks <= DPHigh). At DPLow was unprofitable the use of fungicides and at DPHigh the latter fungicides had the best performances increasing yield relative to the untreated check in > 469 kg ha-1 (+19.1%). Potential yield of soybean in absence of target spot was estimated in 3507 kg ha-1 for 41 trials in Brazil and the percentual reduction for each target spot severity point was calculated in 0.48%, what would represent a reduction of 24% in a hypothetical target spot severity of 50% (ranging from 8% to 42%). The soybean cultivar had a significant effect to explain this wide range of responses: potential losses of 11%, 18.5% and 42% was calculated for cultivar BMX Potência RR, TMG803 and M9144RR respectively at target spot severity = 50%. We observed high variability on the genetic resistance in the tested germplasm: cultivars with very low target spot intensity (BRS360) to highly susceptible cultivars. A single-point disease severity assessment was not as reliably as an integrative three-point assessment, which had no difference with a less time-consuming two-point disease assessment. In trials where 3 C.cassicola isolates from different regions of Brazil were inoculated individually on 3 soybean cultivars contrasting in their resistance level we observed that the incubation period, disease severity, lesion density and lesion size at 14 days after inoculation, were influenced by the cultivar and not by isolate geographical origin. Using disease severity coupled with defoliation assessments throughout the reproductive growth stages, we performed correlations between grain yield and the leaf area injury at different plant positions - growth stages. The best correlation was observed with the assessments at R5.5 for injuries at middle canopy section.
A mancha alvo é uma doença foliar que pode ocasionar perdas de rendimento na cultura da soja. A doença tornou-se recentemente uma preocupação nos principais países produtores de soja (EUA, Brasil e Argentina), devido à crescente intensidade de suas epidemias. Os objetivos deste estudo foram: i) estimar a eficiência de controle da mancha alvo por fungicidas comerciais registrados no Brasil e a resposta em rendimento da soja, identificando fatores que afetam o desempenho dos fungicidas; ii) caracterizar a relação entre a severidade da mancha alvo e o rendimento da soja, utilizando técnicas meta-analíticas e identificar padrões que permitam compreender a heterogeneidade existente nessa relação; iii) explorar a variabilidade da resistência genética de cultivares de soja e verificar a metodologia mais eficiente para discriminar cultivares suscetíveis de resistentes; iv) explorar os efeitos da interação entre a origem do isolado de C. cassiicola e a cultivar de soja no desenvolvimento da epidemia; v) comparar a sensibilidade da posição do estrato do dossel afetado por C. cassiicola na redução do rendimento de grãos. Fungicidas compostos pelos ingredientes ativos fluxapyroxad + piraclostrobina foram os mais eficientes para controlar a mancha alvo, com níveis de controle de até 75%, e sua resposta ao rendimento dependeu da pressão da doença (PD, PDbaixa < 35% de severidade da mancha alvo na testemunha não tratada <= PDalta). Na PDbaixa, a aplicação de fungicidas não foi lucrativa, e em PDalta os fungicidas compostos por fluxapyroxad + piraclostrobina apresentaram os melhores desempenhos, superando o rendimento em relação à testemunha em 469 kg ha-1 (+ 19,1%). O rendimento potencial geral da soja, na ausência da mancha alvo, foi estimado em 3507 kg ha-1 para 41 ensaios distribuídos no Brasil. A redução no rendimento para cada ponto percentual de incremento na severidade da mancha alvo foi calculada em 0,48%. Com isso, níveis (hipotéticos) de severidade de mancha alvo de 50% ocasionariam uma redução de rendimento de 24% (variando entre 8% a 42%). A cultivar de soja teve um efeito significativo para explicar esta grande amplitude de respostas: reduções potenciais (com 50% de severidade) de 11%, 18,5% e 42% foram calculadas, respectivamente, para as cultivares BMX Potência RR, TMG803 e M9144RR. Foi constatada alta variabilidade na resistência genética no germoplasma testado, desde cultivares com intensidade de mancha alvo muito baixa (BRS360) até cultivares altamente suscetíveis. Avaliações da severidade da doença em uma única data não foi tão confiável quanto a avaliação integrada de duas ou três datas. Em experimentos onde 3 isolados de diferentes regiões do Brasil foram inoculados isoladamente em 3 cultivares contrastantes nos níveis de resistência, observou-se que o período de incubação, a severidade da doença, a densidade de lesões e o tamanho das lesões aos 14 dias após a inoculação foram influenciados pela cultivar. Porém, não foi observado efeito da origem geográfica do isolado de C. cassiicola nos componentes monocíclicos avaliados. A severidade da doença em diferentes posições da planta, juntamente com as avaliações de desfolha ao longo dos estádios de crescimento reprodutivo da soja, foi correlacionada ao rendimento de grãos. A melhor correlação entre o rendimento de grãos e a intensidade da doença (severidade + desfolha) foi observada nas avaliações em R5.5 na seção média do dossel.

A redução das perdas é de grande importância para estabilizar a oferta de alimentos ao longo da cadeia de suprimentos e fortalecer a segurança alimentar. O objetivo geral desta pesquisa foi realizar um diagnóstico detalhado sobre as perdas que ocorrem nas diversas atividades logísticas de soja e milho no Brasil, envolvendo a quantificação das perdas físicas, econômicas e ambientais acumuladas na cadeia de suprimentos de tais grãos e a identificação de estratégias e políticas públicas para mitiga-las, através da modelagem de programação matemática. Além disso, foi possível estruturar uma função de perdas na agrologística de grãos a partir de quatro variáveis: tipo de armazenagem, qualidade das vias rodoviárias, modalidade de transporte e canal de comercialização. As perdas totais na cadeia de suprimentos de soja e milho no ano de 2015 no Brasil atingiram o patamar de 2,381 milhões de toneladas, ou seja, algo em torno de 1,303% da produção, incorrendo em perdas econômicas decorrentes do custo de oportunidade com vendas perdidas e de gastos logísticos desnecessários na ordem de R$ 2,04 bilhões (US$ 610,78 milhões). Os cenários avaliados demonstram que a ampliação no uso da armazenagem dentro da fazenda, melhoria nas condições das rodovias brasileiras e das estradas que conectam as fazendas aos armazéns apresentam grande potencial para mitigação das perdas. Apesar da perda relativa de uma atividade logística assumir valor decimal, a perda acumulada ao longo da cadeia de suprimentos assume um valor global bastante considerável. Esse retrato enfatiza a necessidade de conscientização sobre as perdas visando fomentar políticas públicas e gestões eficientes para mitiga-las, dado as externalidades econômicas, ambientais e sociais geradas.
Reducing losses is of great importance in stabilizing the supply of food throughout the supply chain and strengthening food security. The general objective of this research was to perform a detailed diagnosis of the losses that occur in the many logistic activities of soybeans and maize in Brazil, involving the quantification of accumulated physical, economic and environmental losses in the supply chain of such grains and the identification of strategies and public policies to mitigate such losses through mathematical programming modeling. Besides, it was possible to structure a loss function of grains\' agrologistics in terms of four variables: type of storage, quality of roads, modality of transportation and marketing channel. Total losses in the soy and maize supply chain in 2015 in Brazil reached up to 2.381 million tons, or about 1.303% of production, incurring economic reductions due to the cost of loss (reduced sales and unnecessary logistical expenses for the handling of losses) in the order of R$ 2.04 billion (US$ 610.78 million). The evaluated scenarios show that the increase in the use of on-farm storage, the improvement in the conditions of the Brazilian highways and roads that connect the farms to the external warehouses present great potential to mitigate the losses. In spite the relative loss of a logistic activity takes on decimal value, the cumulative loss along the supply chain assumes a fairly considerable overall value. This reality emphasizes the need to raise awareness about losses in order to foster public policies and efficient management to mitigate them, given the created economic, environmental and social externalities.

O controle da ferrugem asiática é altamente dependente do tratamento com fungicidas. A decisão do momento correto da aplicação é fundamental para a eficiência do tratamento, visto que atrasos na efetuação do controle podem torná-lo tão ineficaz quanto à ausência de aplicações. O dano provocado pela ferrugem asiática é decorrente da redução da área foliar, devido à destruição do tecido vegetal e desfolha precoce. Tendo em vista a influência que o atraso no controle tem sobre a ferrugem asiática, e esta sobre a folhagem das plantas de soja, o dano pode ser melhor compreendido com o uso de variáveis que captem modificações na área foliar do hospedeiro. Com os objetivos de avaliar o efeito do atraso no controle da ferrugem asiática sobre o rendimento e os componentes do rendimento, a duração (HAD), a absorção da área foliar sadia (HAA) de plantas de soja e sobre a severidade da doença e examinar as relações entre o rendimento de soja com a duração, absorção da área foliar sadia e severidade da ferrugem asiática, foram conduzidos cinco experimentos no Centro de Pesquisa e Desenvolvimento Agrícola da Arysta LifeScience, em Pereiras-SP. Os experimentos envolveram um tratamento preventivo e tratamentos que corresponderam a atrasos crescentes na efetuação do controle químico. As relações entre os parâmetros citados acima foram avaliadas por meio de testes de comparação de médias (LSD) e regressões lineares e não lineares (p<=0,05). Os resultados mostraram que nas situações em que o início da ferrugem asiática da soja ocorre próximo à fase reprodutiva, o rendimento cai à taxa de -31 kg ha-1 a -15 kg ha-1 por cada dia de atraso no controle, sendo o dano maior nos estádios mais jovens e menor nos estádios mais avançados. Na relação entre o atraso no controle da ferrugem asiática da soja e HAA, 10 MJ m-2 deixam de ser absorvidos por cada dia de atraso no controle. Na relação entre o atraso no controle da ferrugem asiática da soja e HAD, a duração da área foliar sadia diminui 2,4 a 1,4 dias por cada dia em que o controle é atrasado. Na relação entre o rendimento de soja e HAA, são ganhos 2 kg ha-1 para cada MJ m-2 absorvido pela área foliar sadia. Na relação entre o rendimento de soja e HAD, são ganhos de 13 a 9 kg ha-1 para cada dia de duração da área foliar sadia. A relação entre atraso no controle da ferrugem asiática da soja e severidade da doença é de 0,25% ponto percentual para cada dia de atraso no controle. A relação entre o rendimento de soja e severidade da ferrugem asiática é de -36 kg ha-1 por cada ponto percentual de severidade. A variável que melhor se relaciona com o rendimento de soja é a absorção da área foliar sadia (HAA). Tanto HAA quanto HAD são variáveis melhores do que a severidade para serem usadas na quantificação de danos provocados pela ferrugem asiática na soja. Nas situações em que o início da doença ocorre próximo à fase reprodutiva, atrasos no controle da ferrugem asiática superiores a 28 dias apresentam o mesmo resultado que a ausência de controle. Não há redução no rendimento de soja se o início da ferrugem asiática ocorrer a partir do estádio R5.
The control of the asian soybean rust is highly dependent of fungicides treatment. The decision of the correct moment of application is critical for the efficiency of the treatment, since delays in the control can become it so inefficacious as the absence of applications. The damage caused by asian soybean rust is decurrent of the reduction of the leaf area, due to vegetal tissue destruction and early defoliation. In view, the influence that the control delay has on the asian rust, and this on the foliage of the soybean plants, the yield loss can be better understood with the use of variable that catch modifications in the leaf area of the host plant. With the objectives to evaluate the effect of the delay in the asian soybean control on the yield and the yield components, the duration (HAD) and absorption of the healthy leaf area (HAA) of soybean plants and on the disease severity, and to examine the relationship between the soybean yield with the healthy leaf area duration, healthy leaf area absorption and asian soybean rust severity, were conducted five field experiments in Agricultural Research and Development Center of the Arysta LifeScience, in Pereiras-SP. The experiments had involved a preventive treatment and treatments that had corresponded the increasing delays in the chemical control. The relationship between the cited parameters above had been evaluated by averages comparison test (LSD) and linear and non linear regressions (p<=0,05). The results had shown that in the situations where the beginning of the asian soybean rust occurs next to the reproductive phase, the yield fall -31 kg ha-1 to -15 kg ha-1 per each day of control delay, being the loss bigger in youngest stadiums and lesser in oldier stadiums. In the relationship between control delay of the asian soybean rust and HAA, 10MJ m-2 does not absorbed per each day of control delay. In the relationship of the control delay of the asian soybean rust and HAD, the duration of the healthy leaf area reduced 2,4 to 1,4 days per each day where the control is delayed. In the relationship between soybean yield and HAA, were obtained 2 kg ha-1 for each MJ m-2 absorbed by the healthy leaf area. In the relationship between soybean yield and HAD, were obtained 9 to 13 kg ha-1 for each day of healthy leaf area duration. The relationship between control delay of the asian soybean rust and disease severity was of 0,25% percentile point for each day of delay in the control. The relationship between soybean yield and severity of the asian soybean rust were of -36 kg ha-1 for each percentile point of severity. The variable that better becomes related with the yield soybean was the healthy leaf area absorption (HAA). Even HAA as HAD are better variables than severity to be used in the yield losses quantification of the asian soybean rust. In the situations that the beginning of the disease occurs next to reproductive phase, control delay of asian soybean rust higher than 28 days show the same result that the control absence. It does not have reduction in the soybean yield if the beginning of the asian soybean rust occurs after the R5 stadium.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
This research aims to investigate and analyze, from the farmer perspective, the volume and factors that affect Western Paraná soybean harvest losses. The research problem is justified by the losses that occur even with the sector modernization. To results obtaining, primary data were collected through interviews applied to 243 farmers in 8 municipalities in the selected region. From these data, the treatment was carried out by two different analysis forms, at first a Descriptive Analysis, followed by the Principal Components Analysis, which corroborated literature appointments and results obtained at the descriptive analysis. The results pointed out that, despite sector development and modernization, there are still losses that can be controlled, mainly due to factors such as machinery operators specialization degree and climate unpredictability. Also, this research has detected a relationship change between farmers and cooperatives, that previously played a key role in the development of the agroindustrial sector, but which, from the farmer perspective, have lost their initial focus of aid and do not provide more active technical assistance at the proprieties in order to improve crop management. In addition, it was verified that losses related to field relief and topography are closely related to machinery modernization and its age. It is noted that, in order to improve this situation, special emphasis should be given to farmer specialization, aiming the usage of all technology and instruments available for agricultural sector at its full potential.
Esta pesquisa tem por objetivo investigar e analisar, sob a ótica do produtor rural, o volume e os fatores que afetam as perdas na colheita de grãos de soja na região Oeste do Paraná. A problemática da pesquisa se justifica nas perdas que ocorrem mesmo com a modernização do setor. Para a obtenção dos resultados, foram coletados dados primários, por meio de entrevistas com 243 produtores rurais em 8 municípios da região. A partir destes dados, foi realizado seu tratamento resultando em duas formas de análise, primeiramente descritiva e seguida de análise de componentes principais, que veio a corroborar resultados da literatura e aqueles obtidos na análise descritiva. Os resultados apontaram que, apesar do desenvolvimento e modernização do setor, ainda existem perdas passíveis de controle, isso se deve, sobretudo, a fatores como o grau de especialização dos operadores de maquinário e imprevisibilidade do clima. Notou-se também uma modificação na relação entre os produtores e as cooperativas, anteriormente com papel fundamental no desenvolvimento do setor agroindustrial, mas que, sob a ótica do produtor, estas organizações perderam seu foco inicial de auxiliá-lo e não prestam a assistência técnica mais ativa no campo a fim de melhorar o manejo da cultura. Ademais, pode-se verificar que as perdas relativas à relevo e à topografia da área estão intimamente relacionadas à modernização e idade do maquinário utilizado. Constata-se que, para a melhora desse quadro, faz-se necessário fomentar especialmente a especialização dos produtores, a fim de que se utilize todo o potencial da tecnologia e instrumental disponível para o setor agrícola.

Palmer amaranth is a growing concern in the United States. Previously thought to only be able to occupy the southern United States, this plant can now be found throughout the northern states as well. Infestations of Palmer amaranth can now be found in South Dakota and is raising many concerns. Palmer amaranth is characterized by large growth and can be highly competitive with many important crops. Soybean is an important crop in South Dakota, as well as the rest of the world, and has not escaped the detrimental aspects of an infestation of Palmer amaranth. The objectives of this study were to determine the possible impacts Palmer amaranth South Dakota.

Surveys were given to applicators and producers from many counties in South Dakota to gauge public awareness of Palmer amaranth and determine other possible infestations of Palmer amaranth. These surveys were made available at commercial applicator recertification classes throughout South Dakota and the Soy 100 meeting in Brookings, SD.

Growth rates and plant volume and biomass of Palmer amaranth from several seed source locations and local ascensions of common waterhemp and redroot pigweed were examined and compared in eastern South Dakota. Growth studies were conducted near Aurora, SD over two years using three planting dates from mid-May to late-June. Plant volume was measured every 10 to 20 days until harvest beginning in late-July. At harvest, plants were oven-dried and biomass was recorded.

Efficacy of several herbicide treatments were recorded on Palmer amaranth seedlings. Pre- and post-emergence treatments were conducted on Palmer amaranth planted in either sand or potting mix. Post-emergence treatments were applied at the three- to four-leaf stage. Visual ratings of plants were conducted 21 days after treatment.

Soybean yield loss due to Palmer amaranth was determined near Corsica, SD. Palmer amaranth in square meter plots were counted and harvested for biomass when soybeans reached R7 to R8. Plots containing two rows of soybeans were harvested several weeks later and yield loss was determined.

Survey results indicated that more needs to be done to provide information to the public based on respondents’ ability to correctly identify Palmer amaranth, common waterhemp, and redroot pigweed seedlings and mature plants. Several respondents also indicated possible infestations of Palmer amaranth. Not all counties in South Dakota were represented by the study.

Palmer amaranth had greater growth and biomass than either common waterhemp or redroot pigweed. Final volume of Palmer amaranth was greater at lower densities. Growth rates between sampling dates varied among planting dates, which resulted in similarities in final volume among planting dates. Common waterhemp and redroot pigweed shared similar plant volumes and biomass, however, plants in 2015 were larger, possibly due to climatic differences between years.

Herbicides tested that offered the best control of Palmer amaranth was a pre-emergence application of S-metolachlor and a post-emergence application of either dicamba or glufosinate. Glyphosate only provided partial control and mesotrione provided variable control. Atrazine had the little control as a pre- or post-emergence treatment. Thifensulfuron had no control of Palmer amaranth.

Soybean yield loss in 2016 determined an incremental loss of 9% at one Palmer amaranth m^–2. Maximum yield loss of 45% was seen at 15 plants m^–2, however, yield losses at densities slightly lower and higher caused a 35% maximum yield loss prediction. Yield loss in 2017 was variable due to outside factors and a relationship between yield loss and Palmer amaranth density or biomass could not be determined.

Bean pod mottle virus (BPMV, Genus Comovirus, Family: Comoviridae)is an important virus in soybean (Glycine max (L.) Merrill), causing quality and yield loss due to seed coat mottling and seed weight reduction. Although BPMV has been known in Virginia since 1958 and has always been regarded as causing negligible losses, its impact is changing as BPMV incidence has increased in many soybean growing areas of Virginia and the USA in general. From 1997 to 2001, a total of five BPMV isolates (V-W1, V-W2, V-S98-1, V-S98-15 and V-S01-10) were collected in Virginia and characterized. In this study, the effects of these isolates were studied, alone or with Soybean mosaic virus (SMV, Genus Potyvirus, Family Potyviridae) strain SMV G1, and isolates S98-51 and S98-52, on selected soybean cultivars. Individual isolates of BPMV showed variable symptom severity, and resulted in yield loss of between 40.4 to 58.1%, while SMV caused 23.7% in the most severe interactions. Up to 100% yield loss was realized from double inoculations of selected BPMV and SMV isolates, BPMV V-S98-1 + SMV S98-52 and BPMV S98-15 + SMV S98-52 on Hutcheson and Hutcheson Roundup Ready® (BC5) soybeans, respectively. Time of inoculation, a critical factor in the impact of many virus diseases, affected seed coat mottling in four cultivars and seed weight in two cultivars, in tests with four BPMV isolates and three stages of soybean development. All BPMV isolates inoculated to plants at vegetative stage V1-V3 severely increased seed coat mottling and reduced seed weight than those inoculated at V4-V6 and reproductive stage R1-R3. Seedlings grown from non-mottled seeds germinated more uniformly had fewer thin-stemmed seedlings and grew faster than those grown from mottled seeds. Inoculation of various cultivars and breeding lines showed that there was no correlation between the severity of virus-induced foliar symptoms, relative accumulation of SMV, and extent of seed coat mottling. Thus, by avoiding the presence of BPMV at an early growth stage through proper timing of planting to avoid vectors, proper cultural practices like weed control, use of SMV free seeds, and chemical control, it is possible to greatly improve seed quality and reduce yield losses in soybean.
Ph. D.

This thesis focus on the unidimensional adscriptions of value behind industrial soybeans production in Paraguay. The thesis aims to present non-economic Nature’s Contributions to traditional farmers’ quality of life, the role of farmers’ traditional knowledge to display these contributions and the efficiency of such knowledge regarding high productive demands. From a theoretical framework based on nature’s contributions to people, ecosystem services, knowledge systems and conservation, the thesis formulates the following research questions: 1) What drives the prioritization of a single economic value on nature’s contributions to people in rural Paraguay? 2) What is the value of non-economic nature’s contributions, and what is the role of traditional farmers on displaying these values? The study mostly relies in primary data obtained through semi-structured interviews conducted during fieldwork period in the study area of San Pedro, Eastern Paraguay. The results present a plural assessment on nature’s contributions and the adaptation of small farmers to modern farming techniques. The thesis concludes that a perspective dominated by unidimensional value can be socially motivated within the rush for development in Paraguay, a concept tied to economic growth and modernization. In addition, nature’s contributions displayed by small farmers suggest that community-based conservation could represent a more sustainable approach for the farmers’ needs and the current environmental challenges of the country.

The dissertation thesis deals with the analysis of prospective environmentally compatible electrical insulating fluids for electrical engineering in relation to their chemical structure. The thesis starts with the overview of the current state of the art and of the latest trends in the use of synthetic and biodegradable natural oils. In the experimental part were studied these oils: mineral oils, rapeseed oil, sunflower oils, soybean oil, methyl oleate, peanut oil, MCT oil, castor oil and other. Dielectric properties were measured using LRC meter Agilent 4980A including dielectric liquid test fixture Agilent 16452A and also by the Novocontrol Alpha-A analyzer. Electrical properties are presented in the frequency range 10 mHz – 1 MHz range in the temperature interval 253 K to 363 K. The work goes on with the study of the suitability of individual oils for lower temperature, including the impact of the chemical structure and formulation on electrical properties.

Fertilized croplands unintentionally export large amounts of reactive nitrogen (N), which degrades water and air quality and contributes to climate change. In this dissertation, I focus on how these reactive N losses are likely to change in the near future as agriculture intensifies in the tropics, and ecological intensification strategies to mitigate N losses are more widely adopted. I use a combination of empirical field measurements in Mato Grosso, Brazil and Skåne, Sweden, literature review, and statistical models to quantify trends. In chapter one, I quantified emissions of nitric oxide (N₂O) and nitrous oxide (N₂O) in forest, single cropped soybean, and N-fertilized double-cropped soybean-maize at three nitrogen fertilizer levels within the largest area of recent cropland expansion on earth, in the Amazon and Cerrado biomes in Mato Grosso, Brazil. I found that NO emissions do not increase when forests are converted to croplands under current fertilization levels, and that NO will respond more strongly than N₂O fluxes to increases in fertilizer applications. In chapter two, I investigated anion exchange capacity and soil nitrate (NO₃¯) pools in deep soils in Mato Grosso, Brazil in the southern Amazon. I found that soil NO₃¯ pools in the top 8 m increased from 143 kg N ha¯¹ in forest to 1,052 and 1,161 kg N ha¯¹ in soybean and soybean-maize croplands. This NO₃¯ accumulation in croplands compared with forest soils matched the estimated amount of surplus N from the croplands, and could be explained by the soil’s positive charge through its anion exchange capacity. In chapter three, I conducted a meta-analysis of the effects of fertilization amount on of NO₃¯ leaching, N₂O emissions, NO emissions, and ammonia (NH₃) volatilization, totaling over 1,000 observations. I found that the relationship between N inputs and losses differed little between temperate and tropical croplands, although total NO losses were higher in the tropics. Among the potential drivers I studied, the N input rate controlled all N losses, but soil texture and water inputs also controlled NO₃¯ leaching losses. In chapter four, I explored the differences in NO₃¯ leaching, fertilizer N use efficiency, and soil N cycling in perennial wheat, which is being domesticated as a more sustainable alternative to annual crops, and annual wheat at a long-term experimental site in Skåne, Sweden. I found that NO₃ leaching was more than two orders of magnitude lower in perennial wheat, overall ecosystem recovery of fertilizer was quite high and not significantly different between perennial and annual wheat after the first growing season, and that measures of soil N cycling were largely the same between both crops. Together, these chapters highlight that reactive N losses will remain a critical global challenge in the coming decades, but that there are also key opportunities to reduce N losses by increasing the use of perennial crops and focusing tropical agricultural intensification on Oxisol soils which buffer against NO₃¯ leaching.

Across the United States corn-belt region substantial quantities of nitrogen (N) fertilizer are applied in both continuous corn (Zea maysL.) and corn grown in rotation with soybean [Glycine max(L.) Merr.]. When compared to continuous corn, corn grown in rotation with soybean typically receives less applied N fertilizer (typically 20-45 kg ha^-1less) than continuous corn due to expected carryover of N from biological N fixation (BNF) by soybean in the preceding year. However, when current N recommendations are followed in both systems, rotational corn has been shown to lose similar or, in some cases, greater amounts of N through subsurface tile lines than continuous corn although the reports in the literature have been inconsistent. In rain-fed systems a key limitation to many previous studies has been an insufficient number of site-years of data to fully characterize management effects across varied environments. Regardless, the development of better management practices to reduce nitrate leaching losses has largely remained focused on managing N applied to corn and soybean’s role in degradation of surface water has been relatively understudied in tile drained agroecosystems. Therefore, the objectives of this study were to use a 23-yr data record to: (1) compare quantities and patterns of N loss in tile drainage water among a soybean-corn rotation fertilized with the recommended preplant N rate, a soybean-corn rotation fertilized with a N reduced rate applied as a sidedress, continuous corn fertilized with the recommended preplant N rate, and an unfertilized, restored prairie as a natural system control, (2) determine whether and when cumulative soybean-corn load losses in drainage water surpassed that of continuous corn, and (3) evaluate the current recommended N credits from the dual perspective of crop productivity and protection of water quality.

Established in 1992, the Purdue University Water Quality Field Station has continuously assessed field-scale N cycling and losses in tile drains and the N management of the five treatments examined in this study have been maintained since 1995. Treatments were 135 kg N ha^-1 applied in rotational corn as a sidedress at approximately V6 each year (CS-135), 157 kg N ha^-1applied preplant in rotational corn (CS-157), and 180 kg N ha^-1applied preplant in continuous corn (CC-180). All corn plots received 23 kg N ha^-1as starter at planting. A restored perennial prairie control with no fertilizer applied (Pgrass) was utilized to compare and discuss the implications of intensively fertilized annual row crops. The 23-yr data record includes N concentration in drainage water, drainflow volume, N load losses in drainflow, grain yield, tissue N concentrations at harvest and N amounts returned to soil in crop residues and removed in grain.

Analysis of variance found CS-157 resulted in significantly greater daily flow-proportional N concentrations (23-year mean 11.98 mg L^-1) when compared to all other cropping systems (≤ 10.96 mg L^-1). No reportable significant differences occurred in mean annual drainage flow volume among the respective cropping systems. Annual N load loss was statistically similar among cropping systems, ranging between 9.88 to 12.32 kg N ha^-1yr^-1, and these were all significantly higher than the Pgrass control (1.70 kg N ha^-1yr^-1). When corn and soybean years in rotational systems were analyzed separately for leaching losses, CS-157 was significantly higher than CS-135 and CC-180 (14.70, 10.85 and 11.88 kg N ha^-1, respectively) whereas losses by SC-157 and SC-135 were similar averaging 12.26 and 12.13 kg N ha^-1, respectively. Nitrogen treatment did not impact either corn or soybean mean yields. We concluded that soybean BNF production may be a major driver in N load loss in rotational corn when compared to continuous corn and further reductions in load losses from rotational systems will require a focus on managing soybean-derived N. Lastly, future research should include monthly or seasonal assessment of N load losses to better target practices at vulnerable times of nutrient loss.