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1
Brombin, Valentina, Enrico Mistri, Mauro De Feudis, Camilla Forti, Gian Marco Salani, Claudio Natali, Gloria Falsone, Livia Vittori Antisari, and Gianluca Bianchini. "Soil Carbon Investigation in Three Pedoclimatic and Agronomic Settings of Northern Italy." Sustainability 12, no. 24 (December 16, 2020): 10539. http://dx.doi.org/10.3390/su122410539.
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Sustainable agricultural management is needed to promote carbon (C) sequestration in soil, prevent loss of soil fertility, and reduce the release of greenhouse gases. However, the influence of agronomic practices on soil C sequestration depends on the existing pedoclimatic features. We characterized the soils of three farms far away each other in the Emilia-Romagna region (Northern Italy): an organic farm in the Northern Apennines, a biodynamic farm, and a conventional farm on the Po Plain. The total, inorganic, and organic carbon in soil, as well as the distinct humic fractions were investigated, analyzing both the elemental and isotopic (13C/12C) composition. In soils, organic matter appears to be variously affected by mineralization processes induced by microorganisms that consume organic carbon. In particular, organic carbon declined in farms located in the plain (e.g., organic carbon down to 0.75 wt%; carbon stock0-30 cm down to 33 Mg/ha), because of the warmer climate and moderately alkaline environment that enhance soil microbial activity. On the other hand, at the mountain farm, the minimum soil disturbance, the cold climate, and the neutral conditions favored soil C sequestration (organic carbon up to 4.42 wt%; carbon stock0-30 cm up to 160 Mg/ha) in humified organic compounds with long turnover, which can limit greenhouse gas emissions into the atmosphere. This work shows the need for thorough soil investigations, to propose tailored best-practices that can reconcile productivity and soil sustainability.
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Yang, Hui, Yincai Xie, Tongbin Zhu, and Mengxia Zhou. "Reduced Organic Carbon Content during the Evolvement of Calcareous Soils in Karst Region." Forests 12, no. 2 (February 14, 2021): 221. http://dx.doi.org/10.3390/f12020221.
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Understanding the changes in soil organic carbon (SOC) storage is important for accurately predicting ecosystem C sequestration and/or potential C losses, but the relevant information, especially for the evolvement of calcareous soil is limited in karst regions. Three calcareous soils with different evolvement intensities were sampled from an evergreen broadleaved forest in the subtropical region of southwest of China to investigate the changes in different SOC fractions and microbial communities. The results showed that: (1) The contents of SOC, dissolved organic carbon (DOC), mineral protected organic carbon (MOC), and recalcitrant organic carbon (ROC) significantly decreased with increasing evolvement intensity of calcareous soil, but pH and the chemical composition of SOC, including Alkyl C, O-alkyl C, Aromatic C, and Carbonyl C, did not significantly change, suggesting that various SOC fractions synergistically decrease with the evolvement of calcareous soil. (2) The evolvement of calcareous soil had a substantial negative effect on total phospholipid fatty acids (PLFA), bacteria (i.e., Gram positive bacteria and Gram negative bacteria), fungi, and actinomycetes, but did not affect the ratio of fungi to bacteria. This result supported the conclusion that various SOC fractions were synchronously loss with the evolvement of calcareous soil. (3) Results from the multivariate statistical analysis showed a significant correlation between SOC fractions (including SOC, DOC, MOC, and ROC) and soil base cations, mainly calcium (Ca), iron (Fe), and aluminum (Al). This strengthens the fact that SOC stability largely depends on the complex relationship between organic matter and mineral composition in soil. Taken together, the reduction of SOC during the evolvement of soil in the karst areas accords with some mechanisms of previous studies (e.g., microbial composition and soil geochemistry), and also has its own unique characteristics (e.g., the relative contribution of carbons to chemical shift regions of CPMAS 13C-NMR spectra and F:B ratio).
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Ťupek, Boris, Carina A. Ortiz, Shoji Hashimoto, Johan Stendahl, Jonas Dahlgren, Erik Karltun, and Aleksi Lehtonen. "Underestimation of boreal soil carbon stocks by mathematical soil carbon models linked to soil nutrient status." Biogeosciences 13, no. 15 (August 10, 2016): 4439–59. http://dx.doi.org/10.5194/bg-13-4439-2016.
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Abstract. Inaccurate estimate of the largest terrestrial carbon pool, soil organic carbon (SOC) stock, is the major source of uncertainty in simulating feedback of climate warming on ecosystem–atmosphere carbon dioxide exchange by process-based ecosystem and soil carbon models. Although the models need to simplify complex environmental processes of soil carbon sequestration, in a large mosaic of environments a missing key driver could lead to a modeling bias in predictions of SOC stock change.We aimed to evaluate SOC stock estimates of process-based models (Yasso07, Q, and CENTURY soil sub-model v4) against a massive Swedish forest soil inventory data set (3230 samples) organized by a recursive partitioning method into distinct soil groups with underlying SOC stock development linked to physicochemical conditions.For two-thirds of measurements all models predicted accurate SOC stock levels regardless of the detail of input data, e.g., whether they ignored or included soil properties. However, in fertile sites with high N deposition, high cation exchange capacity, or moderately increased soil water content, Yasso07 and Q models underestimated SOC stocks. In comparison to Yasso07 and Q, accounting for the site-specific soil characteristics (e. g. clay content and topsoil mineral N) by CENTURY improved SOC stock estimates for sites with high clay content, but not for sites with high N deposition.Our analysis suggested that the soils with poorly predicted SOC stocks, as characterized by the high nutrient status and well-sorted parent material, indeed have had other predominant drivers of SOC stabilization lacking in the models, presumably the mycorrhizal organic uptake and organo-mineral stabilization processes. Our results imply that the role of soil nutrient status as regulator of organic matter mineralization has to be re-evaluated, since correct SOC stocks are decisive for predicting future SOC change and soil CO2 efflux.
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Hedley, C. B., I. J. Payton, I. H. Lynn, S. T. Carrick, T. H. Webb, and S. McNeill. "Random sampling of stony and non-stony soils for testing a national soil carbon monitoring system." Soil Research 50, no. 1 (2012): 18. http://dx.doi.org/10.1071/sr11171.
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The New Zealand Soil Carbon Monitoring System (Soil CMS) was designed, and has been used, to account for soil organic carbon change under land-use change, during New Zealand’s first Commitment Period (2008–2012) to the Kyoto Protocol. The efficacy of the Soil CMS model has been tested for assessing soil organic carbon stocks in a selected climate–land-use–soil grouping (cell). The cell selected for this test represents an area of 709 683 ha and contains soils with a high-activity clay mineralogy promoting long-term stabilisation of organic matter, and is under low-producing grassland in a dry temperate New Zealand climate. These soils have been sampled at randomly selected positions to assess total soil organic carbon stocks to 0.3 m, and to compare with the modelled value. Results show no significant difference between the field estimation (67 ± 30 Mg C/ha), the mean value of the model calibration dataset (79 ± 28 Mg C/ha), and the value predicted by the model (101 ± 41 Mg C/ha), although all estimates have large uncertainties associated with them. The model predicts national soil organic carbon stocks as a function of soil texture, clay mineralogy, land use, climate class, and a slope–rainfall erosivity product. Components of uncertainty within the model include the size and distribution of the calibration dataset, and lack of representativeness of the calibration soil samples, which were sampled for other reasons, e.g. soil survey and forest mensuration. Our study has shown that major components of uncertainty in our field estimation of soil organic carbon stocks (investigated using the indices reproducibility, RP; and coefficient of variation, CV) are short-range (within-plot) and regional (between-sites) spatial variability. Soil organic carbon stocks vary within our selected climate–land-use–soil cell due to varying stoniness (stony soils RP 44%, CV 21%; non-stony soils RP 27%, CV 13%), soil depth, slope position, and climatic effects. When one outlier soil was removed from the model calibration dataset, and the three very stony sites were removed from the randomly selected field validation set, the model calibration dataset and the field dataset means agreed well (78 ± 26 and 78 ± 21 Mg C/ha, respectively). The higher modelled value, before removal of the outlier, is likely to reflect a bias in the model dataset towards conventionally selected modal profiles containing less stony soils than those encountered by the random sampling strategy of our field campaign. Therefore, our results indicate (1) that the Soil CMS provides an adequate estimation of soil organic carbon for the selected cell, and (2) ongoing refinements are required to reduce the uncertainty of prediction.
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Chan, K. Y., D. P. Heenan, and H. B. So. "Sequestration of carbon and changes in soil quality under conservation tillage on light-textured soils in Australia: a review." Australian Journal of Experimental Agriculture 43, no. 4 (2003): 325. http://dx.doi.org/10.1071/ea02077.
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Light-textured soils (<35% clay) make up more than 80%, by area, of cropping soils in Australia. Many have inherent soil physical problems, e.g. hardsetting, sodicity and low organic carbon levels. Maintenance and improvement of soil organic carbon levels are crucial to preserving the soil structure and physical fertility of these soils.A review of field trials on conservation tillage (3–19 years duration) on these soils in southern Australia revealed that significantly higher soil organic carbon levels compared with conventional tillage were found only in the wetter areas (>500 mm) and the differences were restricted to the top 2.5–10.0 cm. The average magnitude of the difference was lower than that reported in the USA. The lack of a positive response to conservation tillage is probably a reflection of a number of factors, namely low crop yield (due to low rainfall), partial removal of stubble by grazing and the high decomposition rate (due to the high temperature). There is evidence suggesting that under continuous cropping in the drier areas, the soil organic carbon level continues to decline, even under conservation tillage.Better soil structure and soil physical properties, namely macro-porosity, aggregate stability and higher infiltration have been reported under conservation tillage when compared with conventional tillage. However, little information on long-term changes of these properties under conservation tillage is available. As many of these soil qualities are associated directly or indirectly with soil organic carbon levels, the lack of significant increase in the latter suggests that many of these improvements may not be sustainable in the longer term, particularly in the drier areas. Continuous monitoring of long-term changes in the soil organic carbon and soil quality under conservation tillage in different agro-ecological zones is needed.
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Mateja, Muršec, Leveque Jean, Chaussod Remi, and Curmi Pierre. "The impact of drip irrigation on soil quality in sloping orchards developed on marl – A case study." Plant, Soil and Environment 64, No. 1 (January 16, 2018): 20–25. http://dx.doi.org/10.17221/623/2017-pse.
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The impact of drip irrigation on structural stability of soil aggregates was studied in soils of an apple (Malus domestica Borkh.) orchard, developed on marl. The field study was carried out in a sloping (20%) terrain in the north-eastern Slovenia at three slope positions (upslope, mid-slope and downslope), involving a comparison of irrigated versus non-irrigated situations after 6 years of drip irrigation practice. Structural stability was studied in three soil layers (0–5, 5–15 and 15–30 cm) at the end of the irrigation season (in September). In the same samples, soil organic carbon, total carbonates and soil moisture contents were determined. Drip irrigation significantly reduced structural stability and soil organic carbon in the surface soil layer (0–5 cm), while total carbonates increased. Based on the whole set of data, structural stability was strongly positively correlated with total carbonates and negatively correlated with soil organic carbon. This means that the effect of higher level of organic matter mineralisation on structural stability, due to irrigation, is counterbalanced by the increase of total carbonates content in the fine textured calcareous soils. Thus, a negative effect of irrigation on soil organic carbon had less destructive consequences on structural stability than expected.
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Zhang, T. Q., C. F. Drury, and B. D. Kay. "Soil dissolved organic carbon: Influences of water-filled pore space and red clover addition and relationships with microbial biomass carbon." Canadian Journal of Soil Science 84, no. 2 (May 1, 2004): 151–58. http://dx.doi.org/10.4141/s02-030.
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Soil dissolved organic carbon (SDOC) plays an important role in organic C cycling and translocation of nutrients and pollutants in the soil profile. Soil microbial biomass C (MBC) has been used as an indicator of soil quality. Both SDOC and MBC may be affected by management practices and indigenous soil properties, which however are not fully understood. Using a laboratory incubation technique, we determined the effects of red clover (Trifolium pratense L.) addition and soil water saturation as expressed in water-filled pore space (WFPS, 20-95%) on soil SDOC and MBC in three soils from Ontario. The levels of SDOC were the greatest at 20% WFPS, and decreased with increase s in WFPS up to 95%. In comparison with the control, addition of red clover increased SDOC by up to 72% at 20% WFPS, but the effect was minimal or insignificant at WFPS above 50%. Reduction of SDOC with increases of WFPS both with and without red clover was attributed to the increased mineralization of labile organic C, as indicated by CO2 production. Regardless of the legume amendment, soil available N (e.g., mineral N), labile organic C (e.g. initial level of SDOC) or the variable derived from these two measurements, available C:N ratio, were the factors predominately affecting dynamics of SDOC at WPFS from 20 to 50% after 1-mo incubation and at WFPS from 20 to 65% with extended incubation to 3-mo. Soil factors affecting SDOC at WFPS above 85% were total N and pH without red clover, but changed to organic C and soil labile organic C with red clover. High levels of MBC were found to occur mostly with the high WFPS, and were enhanced by red clover addition only in the Perth silt loam. Soil dissolved organic C was significantly related to MBC with WFPS from 20 to 65% without red clover. No relationships between SDOC and MBC were found at WFPS above 65% without red clover and at WFPS from 20 to 95% with red clover. Soil factors affecting SDOC and the availabili ty of SDOC to microbial activity are WFPS dependent and related to soil legume amendment. Key words: Red clover, water-filled pore space, dissolved organic C, microbial biomass C, CO2 emission
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Asanopoulos, Christina H., Jeff A. Baldock, Lynne M. Macdonald, and Timothy R. Cavagnaro. "Quantifying blue carbon and nitrogen stocks in surface soils of temperate coastal wetlands." Soil Research 59, no. 6 (2021): 619. http://dx.doi.org/10.1071/sr20040.
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Coastal wetlands are carbon and nutrient sinks that capture large amounts of atmospheric CO2 and runoff of nutrients. ‘Blue carbon’ refers to carbon stored within resident vegetation (e.g. mangroves, tidal marshes and seagrasses) and soil of coastal wetlands. This study aimed to quantify the impact of vegetation type on soil carbon stocks (organic and inorganic) and nitrogen in the surface soils (0–10 cm) of mangroves and tidal marsh habitats within nine temperate coastal blue carbon wetlands in South Australia. Results showed differences in surface soil organic carbon stocks (18.4 Mg OC ha–1 for mangroves; 17.6 Mg OC ha–1 for tidal marshes), inorganic carbon (31.9 Mg IC ha–1 for mangroves; 35.1 Mg IC ha–1 for tidal marshes), and total nitrogen (1.8 Mg TN ha–1 for both) were not consistently driven by vegetation type. However, mangrove soils at two sites (Clinton and Port Augusta) and tidal marsh soils at one site (Torrens Island) had larger soil organic carbon (SOC) stocks. These results highlighted site-specific differences in blue carbon stocks between the vegetation types and spatial variability within sites. Further, differences in spatial distribution of SOC within sites corresponded with variations in soil bulk density (BD). Results highlighted a link between SOC and BD in blue carbon soils. Understanding the drivers of carbon and nitrogen storage across different blue carbon environments and capturing its spatial variability will help improve predictions of the contribution these ecosystems to climate change mitigation.
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Verberne, E. L. J., J. Hassink, P. de Willigen, J. J. R. Groot, and J. A. van Veen. "Modelling organic matter dynamics in different soils." Netherlands Journal of Agricultural Science 38, no. 3A (September 1, 1990): 221–38. http://dx.doi.org/10.18174/njas.v38i3a.16585.
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A mathematical model was developed to describe carbon (C) and nitrogen (N) cycling in different soil types, e.g. clay and sandy soils. Transformation rates were described by first-order kinetics. Soil organic matter is divided into four fractions (including microbial biomass pool) and three fractions of residues. The fraction of active soil organic matter was assumed to be affected by the extent of physical protection within the soil, as was the soil microbial biomass. The extent of protection influenced the steady state level of the model, and, hence, the mineralization rates. The mineralization rate in fine-textured soils is lower than in coarse-textured soils; in fine-textured soils a larger proportion of the soil organic matter may be physically protected. The availability of organic materials as a substrate for microorganisms is not only determined by their chemical composition, but also by their spatial distribution in the soil. (Abstract retrieved from CAB Abstracts by CABI’s permission)
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Nunes, Márcio R., Harold M. van Es, Kristen S. Veum, Joseph P. Amsili, and Douglas L. Karlen. "Anthropogenic and Inherent Effects on Soil Organic Carbon across the U.S." Sustainability 12, no. 14 (July 15, 2020): 5695. http://dx.doi.org/10.3390/su12145695.
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Soil organic carbon (SOC) influences several soil functions, making it one of the most important soil health indicators. Its quantity is determined by anthropogenic and inherent factors that must be understood to improve SOC management and interpretation. Topsoil (≤15 cm) SOC response to tillage depth and intensity, cover crops, stover removal, manure addition, and various cropping systems was assessed using 7610 observations from eight U.S. regions. Overall, including cover crops, reducing tillage depth and intensity increased SOC. The positive effects of cover crops were more noticeable in South Central, Northwest, and Midwest regions. Removing high rates (>65%) of crop residue decreased SOC in Midwestern and Southeastern soils. Depending on region, applying manure increased SOC by 21 to 41%, compared to non-manured soils. Diversified cropping systems (e.g., those utilizing small mixed vegetables, perennials, or dairy-based systems) had the highest topsoil SOC content, while more intensive annual row crops and large-scale single vegetable production systems, had the lowest. Among inherent factors, SOC increased as precipitation increased, but decreased as mean annual temperature increased. Texture influenced SOC, showing higher values in fine-texture than coarse-texture soils. Finally, this assessment confirmed that SOC can be a sensitive soil health indicator for evaluating conservation practices.
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Wang, F. L., and A. K. Alva. "Transport of soluble organic and inorganic carbon in sandy soils under nitrogen fertilization." Canadian Journal of Soil Science 79, no. 2 (May 1, 1999): 303–10. http://dx.doi.org/10.4141/s97-074.
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Leaching of water soluble soil carbon plays an important role in downward transport of soil nutrients and pollutants and may be influenced by soil and management factors. We examined the leaching of water soluble carbon from two sandy soils under nitrogen fertilization by adapting an intermittent leaching-incubation technique using packed soil columns (94 × 10 cm). After 30 d, cumulative amounts of water-soluble organic carbon (SOC) leached from the Candler and Wabasso sand for various treatments in mg C column−1 were: 77 and 302 (NH4NO3), 64 and 265 (control), and 45 and 239 (isobutylidene diurea, IBDU), respectively. The IBDU and NH4NO3 treatments increased the leaching of water-soluble inorganic carbon (SIC), which ranged from 2 to 38 mg C column−1 over 30 d. At the end of eight cycles of leaching/incubation, the total carbon content increased at depth (control and NH4NO3 treatment) in the Candler sand, but decreased in the Wabasso sand. In the first leaching event, the average rate of SOC leaching from the Wabasso sand was 26 mg C column−1 d−1 which dropped rapidly to about 5 mg C column−1 d−1 towards the end of the experiment. The rate of SOC leaching from the Candler sand was much lower (<8 mg C column−1 d−1) than the rate of SOC leaching from the Wabasso sand. Compared with the unamended treatments, application of NH4NO3 increased and IBDU decreased the leaching of SOC in both soils. These effects of N application were considerable during the initial two to three leaching events only. Our results suggest that the initial rainfalls that follow a dry period may be critical for transporting SOC from the upper layer of these sandy soils. Key words: C leaching, sandy soil, intermittent leaching condition, isobutylidene
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Chan, C., B. D. Kay, and E. G. Gregorich. "Spatial variability in organic carbon stocks on level sites: Relation to vertical penetration of the A horizon." Canadian Journal of Soil Science 89, no. 4 (August 1, 2009): 455–59. http://dx.doi.org/10.4141/cjss08068.
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Understanding the source of spatial variability in soil organic carbon (SOC) stocks will contribute to improved sampling strategies to detect changes in stocks. Most of the variability in SOC stocks in cores collected from small (2 × 3 m) level plots on seven soils with similar cropping histories was related to variation in A horizon depth. Increased variability in horizon depth within plots coincided with the development of zones where the A horizon penetrated to greater depths. Consequently, accurate estimates of SOC stocks cannot be made from shallow measurements at the soil surface (e.g., 10 cm) and minimizing the spatial variability in locations of repeated sampling is necessary when characterizing changes in SOC stocks.Key words: Carbon sequestration, soil organic carbon, spatial variability, soil profile, A horizon
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Chan, KY, and JA Mead. "Surface physical properties of a sandy loam soil under different tillage practices." Soil Research 26, no. 3 (1988): 549. http://dx.doi.org/10.1071/sr9880549.
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The infiltration behaviour and physical properties of a hardsetting sandy loam soil at Cowra, N.S.W., following 2 years of different tillage treatments are reported. Soil that had not been cultivated for 25 years was also investigated at an adjacent pasture site. Infiltration of simulated rainfall at the end of the wheat-growing season gave moisture profiles that were quite different for cultivated, direct drilled and pasture soils. The moisture profile for the cultivated soil suggested the presence of an impeded layer which retarded the movement of infiltrated rain to the subsoil. Porosity measurements confirmed the presence of a layer with significantly fewer macropores (> 300 �m diameter) at the 50-100 mm depth in the cultivated soil, when compared with the direct drilled soil. The old pasture soil had significantly higher porosity (> 300 �m diameter) in the top 100 mm. Aggregate stabilities and organic carbon contents were measured in narrow increments to 150 mm depth for the three different soils, and revealed that a surface 25 mm layer of high organic carbon and highly stable macro-aggregates was present in the pasture and direct drilled soils but absent in the cultivated soil. The unstable surface layer in the conventionally cultivated soil was a consequence of the mixing and inverting action of cultivation and was not due to a net loss of organic carbon from the profile. The organic carbon content of the pasture soil was not significantly different from the direct drilled soil below 50 mm; however, it was significantly lower than the conventionally cultivated soil between 50 and 150 mm depth. These results indicate a need to adopt tillage practices that can preserve the top 25 mm layer of such fragile soils.
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Ansong Omari, Richard, Dorothea Bellingrath-Kimura, Yoshiharu Fujii, Elsie Sarkodee-Addo, Kwame Appiah Sarpong, and Yosei Oikawa. "Nitrogen Mineralization and Microbial Biomass Dynamics in Different Tropical Soils Amended with Contrasting Organic Resources." Soil Systems 2, no. 4 (November 23, 2018): 63. http://dx.doi.org/10.3390/soilsystems2040063.
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The use of location-specific and underutilized organic residues (OR) as soil amendments in small-holder agro-ecosystems is promising. Six ORs (Leucaena leucocephala, Centrosema pubescens, Gliricidia sepium, Pueraria phaseoloides, Azadirachta indica, and Theobroma cacao) were amended to three tropical soils each at 24 mg g−1 dry soil in 120-day incubation study to estimate their nitrogen (N) mineralization and microbial biomass carbon (C) dynamics. Inorganic N contents varied among ORs, soil type and incubation days. Regardless of soil type, Gliricidia had the highest inorganic N among the studied ORs. Mineralization rate of 1.4 to 1.5 mg N kg−1 soil day−1 was observed for Lego and Tec soils, respectively, and was twice higher than Nya soil. However, Nya soil released higher inorganic N than Tec and Lego soils, implying high N mineralization efficiency in the former. Consistent soil pH increase was respectively observed for Theobroma and Pueraria treatments in all soils. Moreover, Theobroma and Pueraria amendments showed the highest soil microbial biomass C (MBC) at the end of the incubation. The assessed soil properties likely affected by the dominant edaphic factors and management influenced differences in MBC and dissolved organic carbon (DOC) while OR quality indices controlled N mineralization. Thus, we conclude that soil properties and OR type are important factors for optimal utilization of organic resources.
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Chan, K. Y., and D. P. Heenan. "Effect of lime (CaCO3) application on soil structural stability of a red earth." Soil Research 36, no. 1 (1998): 73. http://dx.doi.org/10.1071/s97054.
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Changes in soil structural stability as a result of lime application (1·5 t/ha) were monitored over 3 years in a red earth with contrasting initial pH, organic carbon, and structural stability conditions at Wagga Wagga, NSW. The lime was applied to the surface of the direct drilled-soil without any incorporation, but in the case of the cultivated soils, the lime was incorporated into the top 10 cm by scarifying. After liming, an initial temporary reduction in macroaggregate (>2 µm) stability was detected in the immediate surface (0-2·5 cm) of the direct-drilled soil where the highest increases in pH, losses in soil organic carbon, and increases in microbial biomass were also observed. The decrease in structural stability was attributed to lime-induced increases in biological decomposition and the resulting soil organic carbon losses. Subsequent samplings did not detect any difference in either macro- or micro- (<50 µm) aggregate stability of this soil as a result of lime treatment. In contrast, for the 2 cultivated soils which had lower initial structural stability and organic carbon levels, a decline in stability was not observed. Instead, significant increases in macroaggregate and microaggregate stability were detected 1·5 years after lime application. By the end of 3 years, macroaggregate stability of the limed cultivated soils approached that of the direct-drilled soil. The improvement in structural stability extended to 7·5 cm depth 3 years after lime application. Wet-sieving experiments using prolonged periods of shaking indicated enhanced stability of the water-stable aggregates of the limed cultivated soils but not the direct-drilled soils.
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Angelopoulou, Theodora, Nikolaos Tziolas, Athanasios Balafoutis, George Zalidis, and Dionysis Bochtis. "Remote Sensing Techniques for Soil Organic Carbon Estimation: A Review." Remote Sensing 11, no. 6 (March 21, 2019): 676. http://dx.doi.org/10.3390/rs11060676.
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Towards the need for sustainable development, remote sensing (RS) techniques in the Visible-Near Infrared–Shortwave Infrared (VNIR–SWIR, 400–2500 nm) region could assist in a more direct, cost-effective and rapid manner to estimate important indicators for soil monitoring purposes. Soil reflectance spectroscopy has been applied in various domains apart from laboratory conditions, e.g., sensors mounted on satellites, aircrafts and Unmanned Aerial Systems. The aim of this review is to illustrate the research made for soil organic carbon estimation, with the use of RS techniques, reporting the methodology and results of each study. It also aims to provide a comprehensive introduction in soil spectroscopy for those who are less conversant with the subject. In total, 28 journal articles were selected and further analysed. It was observed that prediction accuracy reduces from Unmanned Aerial Systems (UASs) to satellite platforms, though advances in machine learning techniques could further assist in the generation of better calibration models. There are some challenges concerning atmospheric, radiometric and geometric corrections, vegetation cover, soil moisture and roughness that still need to be addressed. The advantages and disadvantages of each approach are highlighted and future considerations are also discussed at the end.
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Brtnický, Martin, Václav Pecina, Tereza Dokulilová, Jan Vopravil, Tomáš Khel, Jan Zloch, and Vítězslav Vlček. "Assessment of Retention Potential and Soil Organic Carbon Density of Agriculturally used Chernozems, Cambisols and Fluvisols." Acta Universitatis Agriculturae et Silviculturae Mendelianae Brunensis 67, no. 5 (2019): 1131–37. http://dx.doi.org/10.11118/actaun201967051131.
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Climate change and the increasing frequency of climatic extremes have led to growing concerns over the sustainability of agriculture during recent years. In this context, soil retention and carbon storage are becoming widely discussed. The aim of this study was to evaluate the retention potential (RP) and soil organic carbon density (SOCD) of Chernozem, Cambisol and Fluvisol topsoil under agricultural management. Despite the different natural assumptions of these soil types, no significant statistical difference was found there. Mean RP values of the soil types varied from 39 to 40 mm and mean SOCD values from 23 to 28 t/ha. This finding may suggest that long-term agricultural management can suppress the naturally diverse potential for water retention and carbon storage of the individual soil types. Comparison of SOCD of the studied soils with agricultural soils in similar studies showed that most of the observed values can be considered as average. Despite this fact, a very strong local degradation has been revealed indicating poor agricultural management. Especially in such cases, there is an urgent need to adjust the management of the agricultural land fund (e.g. increased application of organic fertilizers, change in crop rotation) in order to increase carbon stocks and to improve the water retention capacity of soils.
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Badgery, Warwick, Brian Murphy, Annette Cowie, Susan Orgill, Andrew Rawson, Aaron Simmons, and Jason Crean. "Soil carbon market-based instrument pilot – the sequestration of soil organic carbon for the purpose of obtaining carbon credits." Soil Research 59, no. 1 (2021): 12. http://dx.doi.org/10.1071/sr19331.
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Increasing soil organic carbon (SOC) in Australian farming systems has the potential to offset greenhouse gas emissions. Even though methods for soil carbon (C) sequestration have been developed under the Australian Government’s Emissions Reduction Fund, the scope for farm-scale soil C sequestration is poorly understood. A pilot scheme was developed in Central West New South Wales to trial the use of a market-based instrument to encourage farmers to change farm management to increase SOC. This paper reports changes to SOC stocks measured on farms that were successfully contracted in the pilot. The 10 contracted farms were those that submitted the lowest bid per Mg CO2-e. Four land uses were contracted in the pilot: (1) reduced tillage cropping (reference); (2) reduced tillage cropping with organic amendments (e.g. biosolids or compost); (3) conversion from cropping land to permanent pasture; and (4) conversion from cropping land to permanent pasture with organic amendments. At each site a minimum of 10 locations (sampling points) were sampled and analysed for total carbon (LECO elemental analyser) and bulk density calculated. The SOC stocks (0–0.3 m) were assessed before (2012) and after the pilot (2017; calculated on equivalent soil mass of 2012), with 60% of sites showing a significant increase. Pasture had a higher rate of SOC sequestration than reduced tillage cropping (1.2 vs 0.28 Mg C ha–1 year–1, 0–0.3 m); and organic amendments had higher rates of SOC sequestration than without (1.14 vs 0.78 Mg C ha–1 year–1, 0–0.3 m). The results of the pilot demonstrated increases in SOC, using quantification methods consistent with the current Measurement Method of the Australian Government’s Emissions Reduction Fund policy used to generate Australian Carbon Credit Units. The results require careful interpretation as rates of sequestration are likely to be lower in the longer term than initial rates of change seen in this pilot (five years), and the pilot intentionally selected sites with initially low SOC, which ensured a greater opportunity to sequester SOC.
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Osanai, Yui, Oliver Knox, Gunasekhar Nachimuthu, and Brian Wilson. "Contrasting agricultural management effects on soil organic carbon dynamics between topsoil and subsoil." Soil Research 59, no. 1 (2021): 24. http://dx.doi.org/10.1071/sr19379.
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Agricultural practices (e.g. tillage, crop rotation and fertiliser application) have a strong influence on the balance between carbon (C) input and output by altering physicochemical and microbial properties that control decomposition processes in the soil. Recent studies suggest that the mechanisms by which agricultural practice impacts soil organic carbon (SOC) dynamics in the topsoil may not be the same as those in the subsoil. Here, we assessed SOC stock, soil organic fractions and nitrogen availability to 1.0 m in soils under a cotton (Gossypium hirsutum L.)-based cropping system, and assessed the impact of agricultural management (three historical cropping systems with or without maize (Zea mays L.) rotation) on SOC storage. We found that the maize rotation and changes in the particulate organic fraction influenced SOC stock in the topsoil, although the overall change in SOC stock was small. The large increase in subsoil SOC stock (by 31%) was dominated by changes in the mineral-associated organic fraction, which were influenced by historical cropping systems and recent maize rotation directly and indirectly via changes in soil nitrogen availability. The strong direct effect of maize rotation on SOC stock, particularly in the subsoil, suggests that the direct transfer of C into the subsoil SOC pool may dominate C dynamics in this cropping system. Therefore, agricultural management that affects the movement of C within the soil profile (e.g. changes in soil physical properties) could have a significant consequence for subsoil C storage.
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Ma, Junyong, Hairong Han, and Xiaoqin Cheng. "Soil temperatures and active carbon components as key drivers of C stock dynamics between two different stand ages of Larix principis-rupprechtii plantation." PeerJ 8 (January 21, 2020): e8384. http://dx.doi.org/10.7717/peerj.8384.
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Forest soils sequester a large amount of carbon (C) and have a significant effect on the global C balance. Forests are commonly managed to maintain certain age structures but the effects of this management on soil C pools (kg C m−2) is still uncertain. We compared 40-year-old (1GF) and 24-year-old (2GF) plantations of Larix principis-rupprechtii in North China. Specifically, we measured environmental factors (e.g., soil temperature, moisture, and pH), the active C and nitrogen (N) pools (e.g., soil organic C, soil total N, dissolved organic C and N, microbial biomass C and N), and soil processes (e.g., C mineralization and microbial activity in different seasons) in five soil layers (0–50 cm, 10 cm for each soil layer) across the growing seasons in three 25 m × 25 m plots in each age class (1GF and 2GF). Findings indicated that the soil organic C pool in the older 1GF forest (12.43 kg C m−2) was significantly higher than 2GF forests (9.56 kg C m−2), and that soil temperature in 1GF forests was 9.8 °C, on average, 2.9% warmer than temperature in 2GF forests. The C lost as carbon dioxide (CO2) as a result of mineralization in the 2GF plots may partly explain the lower soil organic C pool in these younger forests; microorganisms likely drive this process.
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Basile-Doelsch, Isabelle, Jérôme Balesdent, and Sylvain Pellerin. "Reviews and syntheses: The mechanisms underlying carbon storage in soil." Biogeosciences 17, no. 21 (October 30, 2020): 5223–42. http://dx.doi.org/10.5194/bg-17-5223-2020.
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Abstract. Soil organic matter (OM) represents a key C pool for climate regulation but also an essential component for soil functions and services. Scientific research in the 21st century has considerably improved our knowledge of soil organic matter and its dynamics, particularly under the pressure of the global disruption of the carbon cycle. This paper reviews the processes that control C dynamics in soil, the representation of these processes over time, and their dependence on variations in major biotic and abiotic factors. The most recent advanced knowledge gained on soil organic matter includes the following. (1) Most organic matter is composed of small molecules, derived from living organisms, without transformation via additional abiotic organic polymerization; (2) microbial compounds are predominant in the long term; (3) primary belowground production contributes more to organic matter than aboveground inputs; (4) the contribution of less biodegradable compounds to soil organic matter is low in the long term; (5) two major factors determine the soil organic carbon production “yield” from the initial substrates: the yield of carbon used by microorganisms and the association with minerals, particularly poorly crystalline minerals, which stabilize microbial compounds; (6) interactions between plants and microorganisms also regulate the carbon turnover time and therefore carbon stocks; (7) among abiotic and biotic factors that regulate the carbon turnover time, only a few are considered in current modeling approaches (i.e., temperature, soil water content, pH, particle size, and sometimes C and N interactions); and (8) although most models of soil C dynamics assume that the processes involved are linear, there are now many indications of nonlinear soil C dynamics processes linked to soil OM dynamics (e.g., priming). Farming practices, therefore, affect soil C stocks not only through carbon inputs but also via their effect on microbial and organomineral interactions, yet it has still not been possible to properly identify the main mechanisms involved in C loss (or gain). Greater insight into these mechanisms and their interdependencies, hierarchy and sensitivity to agricultural practices could provide future levers of action for C sequestration in soil.
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Van Dasselaar, A. P., and E. A. Lantinga. "Modelling the carbon cycle of grassland in the Netherlands under various management strategies and environmental conditions." Netherlands Journal of Agricultural Science 43, no. 2 (June 1, 1995): 183–94. http://dx.doi.org/10.18174/njas.v43i2.575.
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A simulation model of the grassland carbon cycle (CCGRASS) was developed to evaluate the long-term effects of different management strategies and various environmental conditions on carbon sequestration in a loam soil under permanent grassland in the Netherlands. The model predicted that the rate of increase in the amount of soil organic carbon will be greatest at low to moderate application rates of nitrogen (100-250 kg N/ha per year). This is because the annual gross photosynthetic uptake of CO2 in permanent grassland is hardly influenced by the level of N supply. Since N shortage stimulates the growth of the unharvested plant parts (roots and stubble) the carbon supply to the soil is highest at low to moderate N application rates. The rate of increase in soil organic carbon will be greater under grazing than under mowing as a result of a greater amount of carbon added to the soil. Increase of atmospheric CO2 concn may induce an increase in decomposition rate of soil organic matter due to simultaneously increased temperatures. At the same time, plant productivity and thus carbon supply to the soil will be stimulated due to the CO2-fertilization effect. Assuming a temperature increase of 3 degrees C if the present atmospheric CO2 concn doubles, the model predicted that the combined effect of elevated CO2 and temperature will slightly reduce the rate of increase in the amount of organic carbon in grassland soils compared to that under unchanged environmental conditions. There was 2% less carbon sequestration by grassland at the end of a 100 year period as a result of these changes in environmental conditions. The separate effects of increased temperature or elevated CO2 were 10% less and 10% more carbon storage after 100 years, resp.
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Hossain, MD Belal. "Glomalin and Contribution of Glomalin to Carbon Sequestration in Soil: A Review." Turkish Journal of Agriculture - Food Science and Technology 9, no. 1 (January 23, 2021): 191–96. http://dx.doi.org/10.24925/turjaf.v9i1.191-196.3803.
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Arbuscular mycorrhizal fungi (AMF) improves the uptake of nutrients and water to the plants through mutual symbiosis. Only AMF produces glomalin related soil protein (GRSP). Acaulospora morroaiae, Glomus luteum, Glomus verruculosum, Glomus versiforme are the effective glomalin producing AMFs. Mixed primary forest, tropical rainforest, soil organic matter, clay soil, no tillage, quality and quantity of fertilizers, crop rotation, and water stable aggregates are also suitable to increase glomalin production. Glomalin is a glycoprotein that contains 30–40% carbon (C) which is assumed to be stable and persistent in soil. The glomalin can sequestrate more carbon in the soil due to its high carbon and aggregate stability. Greater aggregate stability leads to high organic carbon protection in terrestrial ecosystems. The lowest glomalin content (0.007 mg per gram soil) was found in Antarctic region, and the highest glomalin content (13.50 mg per gram soil) was observed in tropical rainforest. In agricultural soil, glomalin content varies between 0.30 and 0.70 mg per gram soil. The GRSP containing soil organic carbon (SOC) in deeper soil layers was 1.34 to 1.50 times higher than in surface layers. Glomalin can sequestrate 0.24 Mg C ha-1 in soil when present at 1.10±0.04 mg g-1. At elevated CO2 (700 µmol mol-1) level, easily extractable glomalin (EEG) and total glomalin (TG) were 2.76 and 5.67% SOC in the surface soil layer over ambient carbon dioxide (CO2) level. This finding indicates the effective function of GRSP C sequestration in soil under global environmental change scenarios. Glomalin can also protect labile carbon that can help regulating nutrient supply to the plants. No tillage practice causes higher AMF hyphal length, GRSP and water stable aggregate (WSA) compared to that of conventional tillage practice. The current review demonstrated that GRSP is an important tool for carbon storage in deep soils. Glomalin mediates soil aggregates, improves soil quality, increases carbon sequestration and crop production, and mitigates climate change.
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Khan, KT, MTA Chowdhury, and SM Imamul Huq. "Application of biochar and fate of soil nutrients." Bangladesh Journal of Scientific Research 27, no. 1 (January 4, 2016): 11–25. http://dx.doi.org/10.3329/bjsr.v27i1.26221.
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An in vitro incubation study was conducted with soil having seven applications of different treatments of biomass and biochar including a control. The biochar and biomass were applied at a rate of 5 t/h a and incubated at field moisture condition for 30, 60 and 90 days individually in different pots. Total organic carbon (C), total nitrogen, phytoavailable nitrogen (N), phosphorus (P), sulfur (S) and potassium (K) were determined at the end of each incubation period. Total soil organic carbon (SOC), showed a substantial declining trend in all the soils - more prominent in the biochar treated soils than its corresponding biomass treated soils. The pH, total N, phytoavailable N, P, K were substantially higher in the biochar treated soils irrespective of the incubation days compared to the biomass treated soils. Conversely, the available S contents of the biochar treated soils were lower than that of biomass treated soils. The effect of biochar on these nutrients vis-à-vis soil health is discussed.Bangladesh J. Sci. Res. 27(1): 11-25, June-2014
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Chichagova, O. A., and A. E. Cherkinsky. "Problems in Radiocarbon Dating of Soils." Radiocarbon 35, no. 3 (1993): 351–62. http://dx.doi.org/10.1017/s0033822200060355.
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We discuss our progress in three principal applications of 14C dating of recent and fossil soils: 1) new methods; 2) problems of interpreting 14C soil data (e.g.,14C age of soils, age of soils, duration of humus formation, rate of carbon cycling); and 3) 14C analysis of soil organic matter (OM) in pedology and paleogeography (e.g., soil genesis and evolution, humus formation and OM metamorphosis, geochronology and stratigraphy of Late Pleistocene and Holocene sediments). We suggest exploring the above issues in the analysis of each 14C profile in conjunction with paleogeographical data, and by simulation of the carbon cycle in each type of profile.
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Osinaga, Natalia Andrea, Carina Rosa Álvarez, and Miguel Angel Taboada. "Effect of deforestation and subsequent land use management on soil carbon stocks in the South American Chaco." SOIL 4, no. 4 (November 1, 2018): 251–57. http://dx.doi.org/10.5194/soil-4-251-2018.
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Abstract. The subhumid Chaco region of Argentina, originally covered by dry sclerophyll forest, has been subjected to clearing since the end of the 1970s and replacement of the forest by no-till farming. Land use changes produced a decrease in aboveground carbon (C) stored in forests, but little is known about the impact on soil organic C stocks. The aim of this study was to evaluate soil C stocks and C fractions up to 1 m depth in soils under different land use: <10-year continuous cropping, >20-year continuous cropping, warm-season grass pasture and native forest in 32 sites distributed over the Chaco region. The organic C stock content up to 1 m depth expressed as equivalent mass varied as follows: forest (119.3 Mg ha−1) > pasture (87.9 Mg ha−1) > continuous cropping (71.9 and 77.3 Mg ha−1), with no impact of the number of years under cropping. The coarse particle fraction (2000–212 µm) at 0–5 and 5–20 cm depth layers was the most sensitive organic carbon fraction to land use change. Resistant carbon (<53 µm) was the main organic matter fraction in all sample categories except in the forest. Organic C stock, its quality and its distribution in the profile were responsive to land use change. The conversion of the Chaco forest to crops was associated with a decrease of organic C stock up to 1 m depth and with the decrease of the labile fraction. The permanent pastures of warm-season grasses allowed higher C stocks to be sustained than cropping systems and so could be considered a sustainable land use system in terms of soil C preservation. As soil organic C losses were not restricted to the first few centimetres of the soil, the development of models that would allow the estimation of soil organic C changes in depth would be useful to evaluate the impact of land use change on C stocks with greater precision.
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Zethof, Jeroen H. T., Martin Leue, Cordula Vogel, Shane W. Stoner, and Karsten Kalbitz. "Identifying and quantifying geogenic organic carbon in soils – the case of graphite." SOIL 5, no. 2 (December 19, 2019): 383–98. http://dx.doi.org/10.5194/soil-5-383-2019.
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Abstract. A widely overlooked source of carbon (C) in the soil environment is organic carbon (OC) of geogenic origin, e.g. graphite, occurring mostly in metamorphic rocks. Appropriate methods are not available to quantify graphite and to differentiate it from other organic and inorganic C sources in soils. This methodological shortcoming also complicates studies on OC in soils formed on graphite-containing bedrock because of the unknown contribution of a very different soil OC source. In this study, we examined Fourier-transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA) and the smart combustion method for their ability to identify and quantify graphitic C in soils. For this purpose, several artificial soil samples with graphite, CaCO3 and plant litter as the usual C components were created. A graphitic standard was mixed with pure quartz and a natural soil for calibration and validation of the methods over a graphitic C range of 0.1 % to 4 %. Furthermore, rock and soil material from a graphite-bearing schist and a schist without natural graphite were used for method validation. FTIR. As specific signal intensities of distinct graphite absorption bands were missing, calibration could only be performed on general effects of graphite contents on the energy transmitted through the samples. The use of samples from different mineral origins yielded significant matrix effects and hampered the prediction of geogenic graphite contents in soils. TGA. Thermogravimetric analysis, based on changes in mass loss due to differences in thermal stabilities, is suggested as a useful method for graphite identification, although (calcium) carbonate and graphitic C have a similar thermal stability. However, the quantitative estimation of the graphite contents was challenging as dehydroxylation (mass loss) of a wide range of soil minerals occurs in a similar temperature range. Smart combustion. The method is based on measuring the release of C during a combustion program, quantified by a non-dispersive infrared detector (NDIR) as part of a commercial elemental analyser, whereby carbonates and graphitic C could be separated by switching between oxic and anoxic conditions during thermal decomposition. Samples were heated to 400 ∘C under oxygen-rich conditions, after which further heating was done under anoxic conditions till 900 ∘C. The residual oxidizable carbon (ROC), hypothesized to be graphitic C, was measured by switching back to oxygenic conditions at 900 ∘C. Test samples showed promising results for quantifying graphitic C in soils. For the purpose of quantifying graphitic C content in soil samples, smart combustion was the most promising method of those which have been examined in this study. However, caution should be taken with carbonate-rich soils as increasing amounts of carbonate resulted in an underestimation of graphitic C content.
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Tiefenbacher, Alexandra, Taru Sandén, Hans-Peter Haslmayr, Julia Miloczki, Walter Wenzel, and Heide Spiegel. "Optimizing Carbon Sequestration in Croplands: A Synthesis." Agronomy 11, no. 5 (April 29, 2021): 882. http://dx.doi.org/10.3390/agronomy11050882.
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Climate change and ensuring food security for an exponentially growing global human population are the greatest challenges for future agriculture. Improved soil management practices are crucial to tackle these problems by enhancing agro-ecosystem productivity, soil fertility, and carbon sequestration. To meet Paris climate treaty pledges, soil management must address validated approaches for carbon sequestration and stabilization. The present synthesis assesses a range of current and potential future agricultural management practices (AMP) that have an effect on soil organic carbon (SOC) storage and sequestration. Through two strategies—increasing carbon inputs (e.g., enhanced primary production, organic fertilizers) and reducing SOC losses (e.g., reducing soil erosion, managing soil respiration)—AMP can either sequester, up to 714 ± 404 (compost) kg C ha−1 y−1, having no distinct impact (mineral fertilization), or even reduce SOC stocks in the topsoil (bare fallow). Overall, the carbon sequestration potential of the subsoil (>40 cm) requires further investigation. Moreover, climate change, permanent soil sealing, consumer behavior in dietary habits and waste production, as well as the socio-economic constraints of farmers (e.g., information exchange, long-term economic profitability) are important factors for implementing new AMPs. This calls for life-cycle assessments of those practices.
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Lewis, David Bruce, Jason P. Kaye, Randa Jabbour, and Mary E. Barbercheck. "Labile carbon and other soil quality indicators in two tillage systems during transition to organic agriculture." Renewable Agriculture and Food Systems 26, no. 4 (April 20, 2011): 342–53. http://dx.doi.org/10.1017/s1742170511000147.
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AbstractWeed management is one of the primary challenges for producers transitioning from conventional to organic agriculture. Tillage and the use of cover crops are two weed control tactics available to farmers transitioning to organic management, but little is known about their interactive effects on soil quality during the transition period. We investigated the response of soils to tillage and initial cover crop during the 3-year transition to organic in a cover crop–soybean (Glycine max)–maize (Zea mays) rotation in the Mid-Atlantic region of the USA. The tillage treatment contrasted full, inversion tillage with moldboard plowing (FT) versus reduced tillage with chisel plowing (RT). The cover crop treatment contrasted annual versus mostly perennial species during the first year of the rotation. The experiment was initiated twice (Start 1 and Start 2), in consecutive years in adjacent fields. By the end of the experiment, labile carbon, electrical conductivity, pH and soil moisture were all greater under RT than under FT in both starts. Soil organic matter and several other soil attributes were greater under RT than under FT in Start 1, but not in Start 2, perhaps owing to differences between starts in initial field conditions and realized weather. Soil attributes did not differ between the two cover crop treatments. Combining our soils results with agronomic and economic analyses on these plots suggests that using RT during the organic transition can increase soil quality without compromising yield and profitability.
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Jin, Virginia L., Kenneth N. Potter, Mari-Vaughn V. Johnson, R. Daren Harmel, and Jeffrey G. Arnold. "Surface-Applied Biosolids Enhance Soil Organic Carbon and Nitrogen Stocks but Have Contrasting Effects on Soil Physical Quality." Applied and Environmental Soil Science 2015 (2015): 1–10. http://dx.doi.org/10.1155/2015/715916.
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Mid- to long-term impacts of land applying biosolids will depend on application rate, duration, and method; biosolids composition; and site-specific characteristics (e.g., climate, soils). This study evaluates the effects of surface-broadcast biosolids application rate and duration on soil organic carbon (SOC) stocks, soil aggregate stability, and selected soil hydraulic properties in a municipally operated, no-till forage production system. Total SOC stocks (0–45 cm soil) increased nonlinearly with application rate in perennial grass fields treated for 8 years with 0, 20, 40, or 60 Mg of Class B biosolids (DM) ha−1 yr−1(midterm treatments). Soil organic C stocks in long-term treatment fields receiving 20 years of 20 Mg ha−1 yr−1were 36% higher than those in midterm fields treated at the same rate. Surface-applying biosolids had contrasting effects on soil physical properties. Soil bulk density was little affected by biosolids applications, but applications were associated with decreased water-stable soil aggregates, increased soil water retention, and increased available water-holding capacity. This study contrasts the potential for C storage in soils treated with surface-applied biosolids with application effects on soil physical properties, underscoring the importance of site-specific management decisions for the beneficial reuse of biosolids in agricultural settings.
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Sebastià, M. T., E. Marks, and R. M. Poch. "Soil carbon and plant diversity distribution at the farm level in the savannah region of Northern Togo (West Africa)." Biogeosciences Discussions 5, no. 5 (October 28, 2008): 4107–27. http://dx.doi.org/10.5194/bgd-5-4107-2008.
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Abstract. In western Africa, soil organic matter is a source of fertility for food provision and a tool for climate mitigation. In the Savannah region, strong soil degradation linked to an increase in population threatens organic matter conservation and agricultural yield. Soil degradation is also expected to impact biodiversity and, with it, increase the vulnerability of ecosystem goods and services, including the storage of soil organic carbon. Studies of land use, plant species composition and soil fertility were conducted for a conservation project at a demonstration farm in Northern Togo (West Africa), host to various management regimes. Results showed a low organic matter content of the surface soil horizons, often around 0.5%. The highest values were found in a sacred forest within the farm (2.2%). Among crops, rice had the highest soil organic matter, around 1%. In a survey of grasslands, pastures showed the highest organic matter content, with vegetation composition differing from grazed fallows and abandoned grasslands. Plant species richness showed a positive relationship with soil organic matter (R2adj=41.2%), but only by the end of the wet season, when species richness was also highest. Sampling date had a strong effect on vegetation composition. Results showed a strong influence of human activity on soil formation and distribution, and also on plant diversity. The soil characteristics found under the permanent forest suggest a high potential of the soils of the region for improvement of both agricultural yields and as a potential carbon sink relevant to global change policies.
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Tate, K. R., R. H. Wilde, D. J. Giltrap, W. T. Baisden, S. Saggar, N. A. Trustrum, N. A. Scott, and J. P. Barton. "Soil organic carbon stocks and flows in New Zealand: System development, measurement and modelling." Canadian Journal of Soil Science 85, Special Issue (September 1, 2005): 481–89. http://dx.doi.org/10.4141/s04-082.
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An IPCC-based Carbon Monitoring System (CMS) was developed to monitor soil organic C stocks and flows to assist New Zealand to achieve its CO2 emissions reduction target under the Kyoto Protocol. Geo-referenced soil C data from 1158 sites (0.3 m depth) were used to assign steady-state soil C stocks to various combinations of soil class, climate, and land use. Overall, CMS soil C stock estimates are consistent with detailed, stratified soil C measurements at specific sites and over larger regions. Soil C changes accompanying land-use changes were quantified using a national set of land-use effects (LUEs). These were derived using a General Linear Model to include the effects of numeric predictors (e.g., slope angle). Major uncertainties a rise from estimates of changes in the areas involved, the assumption that soil C is at steady state for all land-cover types, and lack of soil C data for some LUEs. Total national soil organic C stocks estimated using the LUEs for 0–0.1, 0.1–0.3, and 0.3–1 m depths were 1300 ± 20, 1590 ± 30, and 1750 ± 70 Tg, respectively. Most soil C is stored in grazing lands (1480 ± 60 Tg to 0.3 m depth), which appear to be at or near steady state; their conversion to exotic forests and shrubland contributed most to the predicted national soil C loss of 0.6 ± 0.2 Tg C yr-1 during 1990–2000. Predicted and measured soil C changes for the grazing-forestry conversion agreed closely. Other uncertainties in our current soil CMS include: spatially integrated annual changes in soil C for the major land-use changes, lack of soil C change estimates below 0.3 m, C losses from erosion, the contribution of agricultural management of organic soils, and a possible interaction between land use and our soil-climate classification. Our approach could be adapted for use by other countries with land-use-change issues that differ from those in the IPCC default methodology. Key words: Soil organic carbon, land-use change, stocks, flows, measurement, modelling, IPCC
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de Jonge, L. W., P. Moldrup, and P. Schjønning. "Soil Infrastructure, Interfaces & Translocation Processes in Inner Space ("Soil-it-is"): towards a road map for the constraints and crossroads of soil architecture and biophysical processes." Hydrology and Earth System Sciences 13, no. 8 (August 19, 2009): 1485–502. http://dx.doi.org/10.5194/hess-13-1485-2009.
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Abstract. Soil functions and their impact on health, economy, and the environment are evident at the macro scale but determined at the micro scale, based on interactions between soil micro-architecture and the transport and transformation processes occurring in the soil infrastructure comprising pore and particle networks and at their interfaces. Soil structure formation and its resilience to disturbance are highly dynamic features affected by management (energy input), moisture (matric potential), and solids composition and complexation (organic matter and clay interactions). In this paper we review and put into perspective preliminary results of the newly started research program "Soil-it-is" on functional soil architecture. To identify and quantify biophysical constraints on soil structure changes and resilience, we claim that new approaches are needed to better interpret processes and parameters measured at the bulk soil scale and their links to the seemingly chaotic soil inner space behavior at the micro scale. As a first step, we revisit the soil matrix (solids phase) and pore system (water and air phases), constituting the complementary and interactive networks of soil infrastructure. For a field-pair with contrasting soil management, we suggest new ways of data analysis on measured soil-gas transport parameters at different moisture conditions to evaluate controls of soil matrix and pore network formation. Results imply that some soils form sponge-like pore networks (mostly healthy soils in terms of agricultural and environmental functions), while other soils form pipe-like structures (agriculturally poorly functioning soils), with the difference related to both complexation of organic matter and degradation of soil structure. The recently presented Dexter et al. (2008) threshold (ratio of clay to organic carbon of 10 kg kg−1) is found to be a promising constraint for a soil's ability to maintain or regenerate functional structure. Next, we show the Dexter et al. (2008) threshold may also apply to hydrological and physical-chemical interface phenomena including soil-water repellency and sorption of volatile organic vapors (gas-water-solids interfaces) as well as polycyclic aromatic hydrocarbons (water-solids interfaces). However, data for differently-managed soils imply that energy input, soil-moisture status, and vegetation (quality of eluded organic matter) may be equally important constraints together with the complexation and degradation of organic carbon in deciding functional soil architecture and interface processes. Finally, we envision a road map to soil inner space where we search for the main controls of particle and pore network changes and structure build-up and resilience at each crossroad of biophysical parameters, where, for example, complexation between organic matter and clay, and moisture-induced changes from hydrophilic to hydrophobic surface conditions can play a role. We hypothesize that each crossroad (e.g. between organic carbon/clay ratio and matric potential) may control how soil self-organization will manifest itself at a given time as affected by gradients in energy and moisture from soil use and climate. The road map may serve as inspiration for renewed and multi-disciplinary focus on functional soil architecture.
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Mitchell, Perry J., André J. Simpson, Ronald Soong, and Myrna J. Simpson. "Biochar amendment altered the molecular-level composition of native soil organic matter in a temperate forest soil." Environmental Chemistry 13, no. 5 (2016): 854. http://dx.doi.org/10.1071/en16001.
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Environmental contextBiochar amendment in soil can sequester carbon but may also stimulate microbial activity, potentially enhancing soil organic matter degradation. We incubated biochar in a temperate forest soil and characterised the soil organic matter composition using molecular-level biomarker and nuclear magnetic resonance techniques. Biochar amendment altered the native soil organic matter composition and decreased the concentration of easily degradable soil organic matter components. AbstractBiochar amendment in soil can sequester carbon and improve soil water and nutrient retention, fertility and plant productivity. However, biochar may stimulate microbial activity, leading to priming or accelerated soil organic matter (OM) degradation, which could alter the native soil OM molecular composition. To investigate this, we amended sugar maple wood biochar (pyrolysed at 500°C) at four concentrations (0, 5, 10 and 20 metric tons per hectare) in a temperate forest soil for 32 weeks. Solvent extraction and CuO oxidation were used to characterise free compounds and lignin-derived phenols respectively at 8 week intervals, while base hydrolysis was used to examine plant wax, cutin and suberin components at the end of the incubation. Stimulated soil microbial activity following an adaptation period (16 weeks) resulted in increased inputs of microbial- and plant-derived soil OM components including solvent-extractable short-chain n-alkanols and n-alkanoic acids, long-chain n-alkanes and n-alkanols, and sugars. Degradation parameters for base-hydrolysable cutin- and suberin-derived compounds did not show any significant degradation of these plant biopolymers. Analysis of lignin-derived phenols revealed lower concentrations of extractable phenols and progressive oxidation of syringyl and vanillyl phenols at higher biochar application rates over time. Solution-state 1H nuclear magnetic resonance analysis of base-extractable soil OM after 32 weeks showed a decrease in the proportion of labile OM components such as carbohydrates and peptides and a relative increase in more recalcitrant polymethylene OM constituents in the amended soils. The biochar-mediated shifts in soil OM composition and reduction in labile carbon may reduce soil fertility in biochar-amended systems with long-term amendment.
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Álvarez, Carina Rosa, Alejandro Oscar Costantini, Alfredo Bono, Miguel Ángel Taboada, Flavio Hernán Gutiérrez Boem, Patricia Lilia Fernández, and Pablo Prystupa. "Distribution and vertical stratification of carbon and nitrogen in soil under different managements in the pampean region of Argentina." Revista Brasileira de Ciência do Solo 35, no. 6 (December 2011): 1985–94. http://dx.doi.org/10.1590/s0100-06832011000600015.
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One of the expected benefits of no-tillage systems is a higher rate of soil C sequestration. However, higher C retention in soil is not always apparent when no-tillage is applied, due e.g., to substantial differences in soil type and initial C content. The main purpose of this study was to evaluate the potential of no-tillage management to increase the stock of total organic C in soils of the Pampas region in Argentina. Forty crop fields under no-tillage and conventional tillage systems and seven undisturbed soils were sampled. Total organic C, total N, their fractions and stratification ratios and the C storage capacity of the soils under different managements were assessed in samples to a depth of 30 cm, in three layers (0-5, 5-15 and 15-30 cm). The differences between the C pools of the undisturbed and cultivated soils were significant (p < 0.05) and most pronounced in the top (0-5 cm) soil layer, with more active C near the soil surface (undisturbed > no-tillage > conventional tillage). Based on the stratification ratio of the labile C pool (0-5/5-15 cm), the untilled were separated from conventionally tilled areas. Much of the variation in potentially mineralizable C was explained by this active C fraction (R² = 0.61) and by total organic C (R² = 0.67). No-till soils did not accumulate more organic C than conventionally tilled soils in the 0-30 cm layer, but there was substantial stratification of total and active C pools at no till sites. If the C stratification ratio is really an indicator of soil quality, then the C storage potential of no-tillage would be greater than in conventional tillage, at least in the surface layers. Particulate organic C and potentially mineralizable C may be useful to evaluate variations in topsoil organic matter.
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Boechat, Cácio Luiz, Jorge Antonio Gonzaga Santos, Adriana Maria de Aguiar Accioly, Marcela Rebouças Bomfim, and Adailton Conceição dos Santos. "Industrial and urban organic wastes increase soil microbial activity and biomass." Revista Brasileira de Ciência do Solo 36, no. 5 (November 2012): 1629–36. http://dx.doi.org/10.1590/s0100-06832012000500027.
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Microbial processes have been used as indicators of soil quality, due to the high sensitivity to small changes in management to evaluate, e.g., the impact of applying organic residues to the soil. In an experiment in a completely randomized factorial design 6 x 13 + 4, (pot without soil and residue or absolute control) the effect of following organic wastes was evaluated: pulp mill sludge, petrochemical complex sludge, municipal sewage sludge, dairy factory sewage sludge, waste from pulp industry and control (soil without organic waste) after 2, 4, 6, 12, 14, 20, 28, 36, 44, 60, 74, 86, and 98 days of incubation on some soil microbial properties, with four replications. The soil microbial activity was highly sensitive to the carbon/nitrogen ratio of the organic wastes. The amount of mineralized carbon was proportional to the quantity of soil-applied carbon. The average carbon dioxide emanating from the soil with pulp mill sludge, corresponding to soil basal respiration, was 0.141 mg C-CO2 100 g-1 soil h-1. This value is 6.4 times higher than in the control, resulting in a significant increase in the metabolic quotient from 0.005 in the control to 0.025 mg C-CO2 g-1 Cmic h-1 in the soil with pulp mill sludge. The metabolic quotient in the other treatments did not differ from the control (p < 0.01), demonstrating that these organic wastes cause no disturbance in the microbial community.
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Harrison, Kevin G. "Using Bulk Soil Radiocarbon Measurements to Estimate Soil Organic Matter Turnover Times: Implications for Atmospheric CO2 Levels." Radiocarbon 38, no. 2 (1996): 181–90. http://dx.doi.org/10.1017/s0033822200017550.
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Although soil contains about three times the amount of carbon present in the preindustrial atmosphere, determining how perturbations (e.g., changing land use, CO2 fertilization, changing climate and anthropogenic nitrogen deposition) alter soil carbon storage and influence atmospheric CO2 levels has proved elusive. Not knowing the soil carbon turnover times causes part of this uncertainty. I outline a strategy for using radiocarbon measurements to estimate soil organic matter turnover times and inventories in native soil. The resulting estimates of carbon exchange produce reasonable agreement with measurements of CO2 fluxes from soil. Furthermore, derivatives of the model are used to explore soil carbon dynamics of cultivated and recovering soil. Because the models can reproduce observed soil 14C measurements in native, cultivated, and recovering ecosystems (i.e., the underlying assumptions appear reasonable), the native model was modified to estimate the potential rate of additional carbon storage because of CO2 fertilization. This process may account for 45–65% of the “missing CO2 sink.”
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Rauber, Luiz Paulo, Cristiano Dela Piccolla, Andréia Patrícia Andrade, Augusto Friederichs, Álvaro Luiz Mafra, Juliano Corulli Corrêa, and Jackson Adriano Albuquerque. "Physical properties and organic carbon content of a Rhodic Kandiudox fertilized with pig slurry and poultry litter." Revista Brasileira de Ciência do Solo 36, no. 4 (August 2012): 1323–32. http://dx.doi.org/10.1590/s0100-06832012000400026.
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The impact of pig slurry and poultry litter fertilization on soils depends on the conditions of use and the amounts applied. This study evaluated the effect of organic fertilizers after different application periods in different areas on the physical properties and organic carbon contents of a Rhodic Kandiudox, in Concordia, Santa Catarina, in Southern Brazil. The treatments consisted of different land uses and periods of pig and poultry litter fertilization: silage maize (M7 years), silage maize (M20 years), annual ryegrass pasture (P3 years), annual ryegrass pasture (P15 years), perennial pasture (PP20 years), yerba mate tea (Mt20 years), native forest (NF), and native pasture without manure application (P0). The 0-5, 5-10 and 10-20 cm soil layers were sampled and analyzed for total organic carbon, total nitrogen and soil physical properties such as density, porosity, aggregation, degree of flocculation, and penetration resistance. The organic carbon levels in the cultivated areas treated with organic fertilizer were even lower than in native forest soil. The organic fertilizers and studied management systems reduced the flocculation degree of the clay particles, and low macroporosity was observed in some areas. Despite these changes, a good soil physical structure was maintained, e.g., soil density and resistance to penetration were below the critical limits, whereas aggregate stability was high, which is important to reduce water erosion in these areas with rugged terrain in western Santa Catarina, used for pig and poultry farming.
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de Jonge, L. W., P. Moldrup, and P. Schjønning. "Soil Infrastructure, Interfaces and Translocation Processes in Inner Space (''Soil-it-is''): towards a road map for the constraints and crossroads of soil architecture and biophysical processes." Hydrology and Earth System Sciences Discussions 6, no. 2 (March 25, 2009): 2633–78. http://dx.doi.org/10.5194/hessd-6-2633-2009.
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Abstract. Soil functions and their impact on health, economy and the environment are evident at the macro scale but determined at the micro scale, based on interactions between soil micro-architecture and the transport and transformation processes occurring in the pore and particle networks and at their interfaces. Soil structure formation and its resilience to disturbance are highly dynamic features affected by management (energy input), moisture (matric potential), and solids composition and complexation (organic carbon, OC, and clay interactions). In this paper we review and put into perspective preliminary results of the newly started research program ''Soil-it-is'' on functional soil architecture. To identify and quantify biophysical constraints on soil structure changes and resilience, we claim that new paradigms are needed to better interpret processes and parameters measured at the bulk soil scale and their links to the seemingly chaotic soil inner space behavior at the micro scale (soil self-organization). As a first step, we revisit the soil matrix (solids phase) and pore system (water and air phases), constituting the complementary and interactive networks of soil infrastructure. For a field-pair with contrasting soil management, we suggest new ways of data analysis on measured soil-gas transport parameters at different moisture conditions to evaluate controls of soil matrix and pore network formation. Results imply that some soils form sponge-like pore networks (mostly healthy soils in terms of environmental functions), while other soils form pipe-like structures (poorly functioning soils), with the difference related to both complexation of organic matter and degradation of soil structure. The recently presented Dexter threshold (ratio of clay to organic carbon of 10 g g−1) is found to be a promising constraint for a soil's ability to maintain or regenerate functional structure. Next, we show the Dexter threshold may also apply to hydrological and physical-chemical interface phenomena including soil-water repellency and sorption of volatile organic vapors (gas-water-solids interfaces) as well as polycyclic aromatic hydrocarbons (water-solids interfaces). However, data for differently-managed soils imply that energy input, soil-moisture status, and vegetation (quality of eluded organic matter) may be equally important constraints together with the complexation and degradation of organic carbon in deciding functional soil architecture and interface processes. Finally, we envision a road map to soil inner space where we search for the main controls of particle and pore network changes and structure build-up and resilience at each crossroad of biophysical parameters, where, for example, complexation between organic matter and clay, and moisture-induced changes from hydrophilic to hydrophobic surface conditions can play a role. We hypothesize that each crossroad (e.g. between OC/clay ratio and matric potential) may initiate breakdown or activation of soil self-organization at a given time as affected by gradients in energy and moisture from soil use and climate. The road map may serve as inspiration for renewed and multi-disciplinary focus on functional soil architecture.
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Li, Wanying, Zhen Guo, Juan Li, and Jichang Han. "Response of the characteristics of organic carbon mineralization of soft rock and soil composed of sand to soil depth." PeerJ 9 (June 4, 2021): e11572. http://dx.doi.org/10.7717/peerj.11572.
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The addition of soft rock to aeolian sandy soil can improve the level of fertility and ability of the soil to sequester carbon, which is of substantial significance to improve the ecological environment of the Mu Us sandy land and supplement newly added cultivated land. S oft rock and sand were combined using the ratio (v/v) of 0:1 (CK), 1:5 (S1), 1:2 (S2), and 1:1 (S3). The process of mineralization of organic carbon at different depths (0–10 cm, 10–20 cm, and 20–30 cm) in the combined soil was studied by 58 days of incubation indoors at a constant temperature. The content of soil nutrient s increased significantly under the S2 and S3 treatments and was higher in the 0–10 cm soil depth. The mineralization of rate of soil organic carbon (SOC) of different combination ratios can be divided into three time periods: the stress mineralization stage (1–7 d), the rapid mineralization stage (7–9 d) and the slow mineralization stage (9–58 d). At the end of incubation, the rates of mineralization of SOC and accumulated mineralization amount (Ct) were relatively large in the 0–10 cm soil depth, followed by the 10–20 cm and 20–30 cm soil layers , indicating that the stability of SOC in the surface layer was poor, which is not conducive to the storage of carbon. The content of potentially mineralizable organic carbon (C0) in the soil was consistent with the trend of change of Ct. Compared with the CK treatment, the cumulative organic carbon mineralization rate (Cr) of the S2 and S3 treatment s decreased by 7.77% and 6.05%, respectively; and the C0/SOC decreased by 22.84% and 15.55%, respectively. Moreover, the Cr and C0/SOC values in the 10–20 cm soil depth were small, which indirectly promoted the storage of organic carbon. With the process of SOC mineralization, the contents of soil microbial biomass carbon (SMBC) and dissolved organic carbon (DOC) tended to decrease compared with the initial contents, with larger amplitudes in the 20–30 cm and 10–20 cm soil depth s, respectively. SOC, total nitrogen, available potassium, SMBC and DOC were all closely related to the process of mineralization of organic carbon. Therefore, the accumulation of soil carbon could be enhanced when the proportion of soft rock and sand composite soil was between 1:2 and 1:1, and the 10–20 cm soil depth was relatively stable. These results provide a theoretical basis for the improvement of desertified land.
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Šoltysová, Božena, and Martin Danilovič. "Tillage in Relation to Distribution of Nutrients and Organic Carbon in the Soil." Agriculture (Polnohospodárstvo) 57, no. 1 (May 1, 2011): 21–30. http://dx.doi.org/10.2478/v10207-011-0003-2.
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Tillage in Relation to Distribution of Nutrients and Organic Carbon in the SoilChanges of total nitrogen, available phosphorus, available potassium and soil organic carbon were observed on gleyic Fluvisols (locality Milhostov) at the following crops: grain maize (2005), spring barley (2006), winter wheat (2007), soya (2008), grain maize (2009). The experiment was realized at three soil tillage technologies: conventional tillage, reduced tillage and no-tillage. Soil samples were collected from three depths (0-0.15 m; 0.15-0.30 m; 0.30-0.45 m). The ratio of soil organic carbon to total nitrogen was also calculated.Soil tillage affects significantly the content of total nitrogen in soil. The difference between the convetional tillage and soil protective tillages was significant. The balance showed that the content of total nitrogen decreased at reduced tillage by 5.2 rel.%, at no-tillage by 5.1 rel.% and at conventional tillage by 0.7 rel.%.Similarly, the content of organic matter in the soil was significantly affected by soil tillage. The content of soil organic carbon found at the end of the research period was lower by 4.1 rel.% at reduced tillage, by 4.8 rel.% at no-tillage and by 4.9 rel.% at conventional tillage compared with initial stage. The difference between the convetional tillage and soil protective tillages was significant.Less significant relationship was found between the soil tillage and the content of available phosphorus. The balance showed that the content of available phosphorus was increased at reduced tillage (by 4.1 rel.%) and was decreased at no-tillage (by 9.5 rel.%) and at conventional tillage (by 3.3 rel.%).Tillage did not significantly affect the content of available potassium in the soil.
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Andres-Huayanay, Yan. "Carbon content in a system of avocado production (Persea americana Mill) in Pillco marca - Huánuco - 2018." Revista Investigación Agraria. 2, no. 1 (April 10, 2020): 39–49. http://dx.doi.org/10.47840/reina20205.
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The investigation was carried out in a system of avocado production (Persea americana Mill) var. Has and strong, politically located in the Center for Fruit and Fruit Research (CIFO) - Huanuco. In order to determine the content of organic carbon (COS) at three depths of the soil and estimate the carbon fixed in the aerial and underground biomass of avocado plants by using allometric equations. The methodology used for the field sampling process of probabilistic COS in its Composite Random Sampling form, while for aerial and underground biomes in its optimal stratified sampling form. It was determined that the storage of total organic carbon in the soil by surface between plant and under the tree from 0 to 10 cm deep presents the lowest tendency to store less carbon 9.45 and 10.37 t C/ha respectively. However, as soil depth increases, the rate of organic carbon fixation in the soil tends to increase 17.79 and 10.98 t C/ha from 20 to 30 cm deep. As well as the area and underground biomass of the avocado plants of 7 years of age. The avocado evaluated reached storing 30,239 t C/ha in the aerial biomass and 6,918 t C/ha in the underground biomass. The carbon fixation rate in avocado plants to date stores 5,308 t/ha in total biomass. Keywords: Organic carbon, soil, storage, biomass, fixation rate.
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Zhou, Jizhong, Beicheng Xia, David S. Treves, L. Y. Wu, Terry L. Marsh, Robert V. O’Neill, Anthony V. Palumbo, and James M. Tiedje. "Spatial and Resource Factors Influencing High Microbial Diversity in Soil." Applied and Environmental Microbiology 68, no. 1 (January 2002): 326–34. http://dx.doi.org/10.1128/aem.68.1.326-334.2002.
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ABSTRACT To begin defining the key determinants that drive microbial community structure in soil, we examined 29 soil samples from four geographically distinct locations taken from the surface, vadose zone, and saturated subsurface using a small-subunit rRNA-based cloning approach. While microbial communities in low-carbon, saturated, subsurface soils showed dominance, microbial communities in low-carbon surface soils showed remarkably uniform distributions, and all species were equally abundant. Two diversity indices, the reciprocal of Simpson’s index (1/D) and the log series index, effectively distinguished between the dominant and uniform diversity patterns. For example, the uniform profiles characteristic of the surface communities had diversity index values that were 2 to 3 orders of magnitude greater than those for the high-dominance, saturated, subsurface communities. In a site richer in organic carbon, microbial communities consistently exhibited the uniform distribution pattern regardless of soil water content and depth. The uniform distribution implies that competition does not shape the structure of these microbial communities. Theoretical studies based on mathematical modeling suggested that spatial isolation could limit competition in surface soils, thereby supporting the high diversity and a uniform community structure. Carbon resource heterogeneity may explain the uniform diversity patterns observed in the high-carbon samples even in the saturated zone. Very high levels of chromium contamination (e.g., >20%) in the high-organic-matter soils did not greatly reduce the diversity. Understanding mechanisms that may control community structure, such as spatial isolation, has important implications for preservation of biodiversity, management of microbial communities for bioremediation, biocontrol of root diseases, and improved soil fertility.
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Voltr, Václav, Ladislav Menšík, Lukáš Hlisnikovský, Martin Hruška, Eduard Pokorný, and Lubica Pospíšilová. "The Soil Organic Matter in Connection with Soil Properties and Soil Inputs." Agronomy 11, no. 4 (April 15, 2021): 779. http://dx.doi.org/10.3390/agronomy11040779.
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The content of organic matter in the soil, its labile (hot water extractable carbon–HWEC) and stable (soil organic carbon–SOC) form is a fundamental factor affecting soil productivity and health. The current research in soil organic matter (SOM) is focused on individual fragmented approaches and comprehensive evaluation of HWEC and SOC changes. The present state of the soil together with soil’s management practices are usually monitoring today but there has not been any common model for both that has been published. Our approach should help to assess the changes in HWEC and SOC content depending on the physico-chemical properties and soil´s management practices (e.g., digestate application, livestock and mineral fertilisers, post-harvest residues, etc.). The one- and multidimensional linear regressions were used. Data were obtained from the various soil´s climatic conditions (68 localities) of the Czech Republic. The Czech farms in operating conditions were observed during the period 2008–2018. The obtained results of ll monitored experimental sites showed increasing in the SOC content, while the HWEC content has decreased. Furthermore, a decline in pH and soil´s saturation was documented by regression modelling. Mainly digestate application was responsible for this negative consequence across all soils in studied climatic regions. The multivariate linear regression models (MLR) also showed that HWEC content is significantly affected by natural soil fertility (soil type), phosphorus content (−30%), digestate application (+29%), saturation of the soil sorption complex (SEBCT, 21%) and the dose of total nitrogen (N) applied into the soil (−20%). Here we report that the labile forms (HWEC) are affected by the application of digestate (15%), the soil saturation (37%), the application of mineral potassium (−7%), soil pH (−14%) and the overall condition of the soil (−27%). The stable components (SOM) are affected by the content of HWEC (17%), soil texture 0.01–0.001mm (10%), and input of organic matter and nutrients from animal production (10%). Results also showed that the mineral fertilization has a negative effect (−14%), together with the soil depth (−11%), and the soil texture 0.25–2 mm (−21%) on SOM. Using modern statistical procedures (MRLs) it was confirmed that SOM plays an important role in maintaining resp. improving soil physical, biochemical and biological properties, which is particularly important to ensure the productivity of agroecosystems (soil quality and health) and to future food security.
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Wu, Y., G. Xu, J. N. Sun, and H. B. Shao. "Does thermal carbonization (Biochar) of organic material increase more merits for their amendments of sandy soil?" Solid Earth Discussions 6, no. 1 (February 14, 2014): 535–58. http://dx.doi.org/10.5194/sed-6-535-2014.
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Abstract. Organic materials (e.g. furfural residue) are generally believed to improve the physical and chemical properties of the soils with low fertility. Recently, biochar have been received more attention as a possible measure to improve the carbon balance and improve soil quality in some degraded soils. However, little is known about their different amelioration of a sandy saline soil. In this study, 56d incubation experiment was conducted to evaluate the influence of furfural and its biochar on the properties of saline soil. The results showed that both furfural and biochar greatly reduced pH, increased soil organic carbon (SOC) content and cation exchange capacity (CEC), and enhanced the available phosphorus (P) in the soil. Furfural is more efficient than biochar in reducing pH: 5% furfural lowered the soil pH by 0.5–0.8 (soil pH: 8.3–8.6), while 5% biochar decreased by 0.25–0.4 due to the loss of acidity in pyrolysis process. With respect to available P, 5% of the furfural addition increased available P content by 4–6 times in comparison to 2–5 times with biochar application. In reducing soil exchangeable sodium percentage (ESP), biochar is slightly superior to furfural because soil ESP reduced by 51% and 43% with 5% furfural and 5% biochar addition at the end of incubation. In addition, no significant differences were observed between furfural and biochar about their capacity to retain N, P in leaching solution and to increase CEC in soil. These facts may be caused by the relatively short incubation time. In general, furfural and biochar have different amendments depending on soil properties: furfural was more effectively to decrease pH and to increase available P, whereas biochar played a more important role in increasing SOC and reducing ESP of saline soil.
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Guo, Zhen, Jichang Han, Yan Xu, Yangjie Lu, Chendi Shi, Lei Ge, Tingting Cao, and Juan Li. "The mineralization characteristics of organic carbon and particle composition analysis in reconstructed soil with different proportions of soft rock and sand." PeerJ 7 (September 16, 2019): e7707. http://dx.doi.org/10.7717/peerj.7707.
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The organic carbon mineralization process reflects the release intensity of soil CO2. Therefore, the study of organic carbon mineralization and particle composition analysis of soft rock and sand compound soil can provide technical support and a theoretical basis for soil organic reconstruction (soil structure, materials and biological nutrition). Based on previous research, four treatments were selected: CK (soft rock:sand=0:1), C1 (soft rock:sand=1:5), C2 (soft rock:sand=1:2) and C3 (soft rock:sand=1:1), respectively. Specifically, we analyzed the organic carbon mineralization process and soil particle composition by lye absorption, laser granulometer, and scanning electron microscope. The results showed that there was no significant difference in organic carbon content between C1, C2 , and C3 treatments, but they were significantly higher than in the CK treatment (P < 0.05). The organic carbon mineralization rate in each treatment accords with a logarithmic function throughout the incubation period (P < 0.01), which can be divided into a rapid decline phase in days 1 to 11 followed by a steady decline phase in days 11 to 30. The cumulative mineralization on the 11th day reached 54.96%–74.44% of the total mineralization amount. At the end of the incubation, the cumulative mineralization and potential mineralizable organic carbon content of the C1, C2 and C3 treatments were significantly higher than those of the CK treatment. The cumulative mineralization rate was also the lowest in the C1 and C2 treatment. The turnover rate constant of soil organic carbon in each treatment was significantly lower than that of the CK treatment, and the residence time increased. With the increase of volume fraction of soft rock, the content of silt and clay particles increased gradually, the texture of soil changed from sandy soil to sandy loam, loam , and silty loam, respectively. With the increase of small particles, the structure of soil appear ed to collapse when the volume ratio of soft rock was 50%. A comprehensive mineralization index and scanning electron microscopy analysis, when the ratio of soft rock to sand volume was 1:5–1:2, this can effectively increase the accumulation of soil organic carbon. Then, the distribution of soil particles was more uniform, the soil structure was stable (not collapsed), and the mineralization level of unit organic carbon was lower. Our research results have practical significance for the large area popularization of soft rock and sand compound technology.
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Olson, Kenneth R., Stephen A. Ebelhar, and James M. Lang. "Effects of 24 Years of Conservation Tillage Systems on Soil Organic Carbon and Soil Productivity." Applied and Environmental Soil Science 2013 (2013): 1–10. http://dx.doi.org/10.1155/2013/617504.
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The 24-year study was conducted in southern Illinois (USA) on land similar to that being removed from Conservation Reserve Program (CRP) to evaluate the effects of conservation tillage systems on: (1) amount and rates of soil organic carbon (SOC) storage and retention, (2) the long-term corn and soybean yields, and (3) maintenance and restoration of soil productivity of previously eroded soils. The no-till (NT) plots did store and retain 7.8 Mg C ha−1more and chisel plow (CP) −1.6 Mg C ha−1less SOC in the soil than moldboard plow (MP) during the 24 years. However, no SOC sequestration occurred in the sloping and eroding NT, CP, and MP plots since the SOC level of the plot area was greater at the start of the experiment than at the end. The NT plots actually lost a total of −1.2 Mg C ha−1, the CP lost −9.9 Mg C ha−1, and the MP lost −8.2 Mg C ha−1during the 24-year study. The long-term productivity of NT compared favorably with that of MP and CP systems.
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van der Voort, Tessa Sophia, Frank Hagedorn, Cameron McIntyre, Claudia Zell, Lorenz Walthert, Patrick Schleppi, Xiaojuan Feng, and Timothy Ian Eglinton. "Variability in <sup>14</sup>C contents of soil organic matter at the plot and regional scale across climatic and geologic gradients." Biogeosciences 13, no. 11 (June 14, 2016): 3427–39. http://dx.doi.org/10.5194/bg-13-3427-2016.
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Abstract. Soil organic matter (SOM) forms the largest terrestrial pool of carbon outside of sedimentary rocks. Radiocarbon is a powerful tool for assessing soil organic matter dynamics. However, due to the nature of the measurement, extensive 14C studies of soil systems remain relatively rare. In particular, information on the extent of spatial and temporal variability in 14C contents of soils is limited, yet this information is crucial for establishing the range of baseline properties and for detecting potential modifications to the SOM pool. This study describes a comprehensive approach to explore heterogeneity in bulk SOM 14C in Swiss forest soils that encompass diverse landscapes and climates. We examine spatial variability in soil organic carbon (SOC) 14C, SOC content and C : N ratios over both regional climatic and geologic gradients, on the watershed- and plot-scale and within soil profiles. Results reveal (1) a relatively uniform radiocarbon signal across climatic and geologic gradients in Swiss forest topsoils (0–5 cm, Δ14C = 130 ± 28.6, n = 12 sites), (2) similar radiocarbon trends with soil depth despite dissimilar environmental conditions, and (3) micro-topography dependent, plot-scale variability that is similar in magnitude to regional-scale variability (e.g., Gleysol, 0–5 cm, Δ14C 126 ± 35.2, n = 8 adjacent plots of 10 × 10 m). Statistical analyses have additionally shown that Δ14C signature in the topsoil is not significantly correlated to climatic parameters (precipitation, elevation, primary production) except mean annual temperature at 0–5 cm. These observations have important consequences for SOM carbon stability modelling assumptions, as well as for the understanding of controls on past and current soil carbon dynamics.
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Wilken, Florian, Michael Sommer, Kristof Van Oost, Oliver Bens, and Peter Fiener. "Process-oriented modelling to identify main drivers of erosion-induced carbon fluxes." SOIL 3, no. 2 (May 5, 2017): 83–94. http://dx.doi.org/10.5194/soil-3-83-2017.
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Abstract. Coupled modelling of soil erosion, carbon redistribution, and turnover has received great attention over the last decades due to large uncertainties regarding erosion-induced carbon fluxes. For a process-oriented representation of event dynamics, coupled soil–carbon erosion models have been developed. However, there are currently few models that represent tillage erosion, preferential water erosion, and transport of different carbon fractions (e.g. mineral bound carbon, carbon encapsulated by soil aggregates). We couple a process-oriented multi-class sediment transport model with a carbon turnover model (MCST-C) to identify relevant redistribution processes for carbon dynamics. The model is applied for two arable catchments (3.7 and 7.8 ha) located in the Tertiary Hills about 40 km north of Munich, Germany. Our findings indicate the following: (i) redistribution by tillage has a large effect on erosion-induced vertical carbon fluxes and has a large carbon sequestration potential; (ii) water erosion has a minor effect on vertical fluxes, but episodic soil organic carbon (SOC) delivery controls the long-term erosion-induced carbon balance; (iii) delivered sediments are highly enriched in SOC compared to the parent soil, and sediment delivery is driven by event size and catchment connectivity; and (iv) soil aggregation enhances SOC deposition due to the transformation of highly mobile carbon-rich fine primary particles into rather immobile soil aggregates.
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Solarte-Guerrero, Geovanny, Dayana Marcela Males, and Angela Natalia Ortiz. "Quantification of carbon capture in different soil uses." Revista de Ciencias Agrícolas 37, no. 1 (June 20, 2020): 59–69. http://dx.doi.org/10.22267/rcia.203701.127.
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Carbon sequestration by soils in different production systems contributes greatly to the reduction of greenhouse gases. The objective of this study was to quantify the carbon stored in four land uses at different soil depths. To this end, a 22 factorial experiment in complete randomized block design (CRBD) was carried out. The factor A: land uses (natural pastures, shelterbelts, fodder banks, and potato crop) and the factor B: two soil depths (30 and 60cm), with three replications. . As a result, statistical differences were found among soil uses (p>0.0573) and between depths of 30 and 60cm (p<0.0061). However, no statistically significant differences were found in the interaction land-use and depth (P > 0.0659). The fodder bank presented a higher organic carbon content (139.85tC.ha-1) at 60cm depth and the potato monoculture (63.32tC.ha-1) at 30cm depth while, at both depths, natural pasture reported lower values (54.45 and 60.02tC.ha-1). Hence, the importance of productive systems to accumulate more carbon at greater depths of soil (60cm) compared to lower depths (30cm), which may be linked to agricultural opperations made on the soi surface, generating carbon leakage.