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Soil organic carbon (SOC) storage plays a major role in the global carbon cycle and is affected by many factors including land use/management changes (e.g., biofuel production-oriented changes). However, the contributions of various factors to SOC changes are not well understood and quantified. This study was designed to investigate the impacts of changing farming practices, initial SOC levels, and biological enhancement of grain production on SOC dynamics and to attribute the relative contributions of major driving forces (CO2 enrichment and farming practices) using a fractional factorial modeling design. The case study at a crop site in Iowa in the United States demonstrated that the traditional corn-soybean (CS)...
Terrestrial carbon sequestration potential is widely considered as a realistic option for mitigating greenhouse gas emissions. However, this potential may be threatened by global changes including climate, land use, and management changes such as increased corn stover harvesting for rising production of cellulosic biofuel. Therefore, it is critical to investigate the dynamics of soil organic carbon (SOC) at regional or global scale. This study simulated the corn production and spatiotemporal changes of SOC in the U.S. Temperate Prairies, which covers over one-third of the U.S. corn acreage, using a biogeochemical model with multiple climate and land-use change projections. The corn production (either grain yield...
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Soil organic carbon is a general term for the total of all the different non-living organic compounds in the soil, it also excludes dead plants and animals. The organic carbon in the soil is used by plants for nourishment as they grow, and the plants themselves replenish the resource when they decay after they die. Although it would seem that high densities of soil carbon would correspond to areas where vegetation thrives, this is not necessarily the case. For example, the regions of the world categorized as tropical rainforest typically have very low quality soils - not because the soils are bad, rather because the highly active vegetation on the surface has already extracted most of the nutrient from the soil....
The large land area occupied by arid lands, roughly 36% to 40% globally, underscores the importance for understanding how these ecosystems function in the global carbon cycle. Few studies have directly examined soil organic carbon (SOC) dynamics and the effect of vegetation on SOC and microbial community structure in arid ecosystems. The objective of this study was to determine the effect of vegetation type on SOC dynamics in an arid, hyperthermic Sonoran Desert ecosystem. We specifically examined the influence of Prosopis velutina (mesquite), Larrea tridentata (creosote), and a combination of Bouteloua barbata, Bouteloua aristidoides, Aristida adscensionis, and Cynodon dactylon (mixed grass) vegetation types on...
Water erosion results in the mobilization and depletion of soil organic carbon (SOC), but studies providing direct experimental evidence of eroded C mineralization and its linkage to the global C cycle are lacking. A study was conducted to determine the mineralization of SOC in runoff from a southwestern Ohio Crosby soil (fine, mixed, mesic Aeric Ochraqualf) that had been under no-till (NT), chisel till (CT) and moldboard plow (MP) for 38 years. To simulate present and future soil erosion conditions, the 0–3 and 5–8 cm soil layers from triplicate soil blocks extracted from each tillage practice were used. Soil layers were transferred to runoff trays and simulated rainfall (30±5 mm h−1) was applied for 1 h. Runoff...
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Nutrient retention capacity is of particular importance for the effectiveness of fertilizer applications and is therefore of special relevance for intermediate and high input level cropping conditions. Nutrient retention capacity refers to the capacity of the soil to retain added nutrients against losses caused by leaching. Plant nutrients are held in the soil on the exchange sites provided by the clay fraction, organic matter and the clay-humus complex. Losses vary with the intensity of leaching which is determined by the rate of drainage of soil moisture through the soil profile. Soil texture affects nutrient retention capacity in two ways, through its effects on available exchange sites on the clay minerals and...
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This soil quality is decisive for successful low level input farming and to some extent also for intermediate input levels. Diagnostics related to nutrient availability are manifold. Important soil characteristics of the topsoil (0-30 cm) are: Texture/Structure, Organic Carbon (OC), pH and Total Exchangeable Bases (TEB). For the subsoil (30-100 cm), the most important characteristics considered are: Texture/Structure, pH and TEB. The soil characteristics relevant to soil nutrient availability are to some extent correlated. For this reason, the most limiting soil characteristic is combined in the evaluation with the average of the remaining less limiting soil characteristics to represent soil quality SQ1. Soil...
Agricultural residues have been identified as a significant potential resource for bioenergy production, but serious questions remain about the sustainability of harvesting residues. Agricultural residues play an important role in limiting soil erosion from wind and water and in maintaining soil organic carbon. Because of this, multiple factors must be considered when assessing sustainable residue harvest limits. Validated and accepted modeling tools for assessing these impacts include the Revised Universal Soil Loss Equation Version 2 (RUSLE2), the Wind Erosion Prediction System (WEPS), and the Soil Conditioning Index. Currently, these models do not work together as a single integrated model. Rather, use of these...
Soil organic carbon (SOC) is a biophysical parameter, which is also directly linked to above ground land use and land cover (LULC). Currently changes in LULC and variations in SOC often are studied and modeled separately. However, both are conjoined and should be seen as part of a cascading ecosystem framework. This is not only true for SOC but also for other biophysical parameters which are governed by human activities. At a watershed scale, this relationship is exceptionally important and the focus should be towards studying the impact of LULC change on the levels of SOC in spatially explicit terms. To advance knowledge on this front, we studied transformations of LULC, erosion and SOC from the start of settled...
Land use land cover (LULC) plays an important role in influencing the spatial intensity of water erosion which is the primary governor of horizontal translocation of soil organic carbon (SOC). The fate of redistributed SOC through erosion remains debatable and the mineralization rate of exposed SOC protected in soil aggregates is the major focus of this argument. Cohesive spatially explicit modeling of SOC and erosion can potentially reduce some of the controversy. To this end we simulated erosion/deposition, and photosynthetic (in situ) flux of SOC in a small watershed of ~ 28.42 ha, located in the Big Creek basin of southern Illinois. The main objectives of this research were: (a) to study erosion and deposition...
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Diagnostic characteristics to indicate soil workability vary by type of management applied. Workability or ease of tillage depends on interrelated soil characteristics such as texture, structure, organic matter content, soil consistence/bulk density, the occurrence of gravel or stones in the profile or at the soil surface, and the presence of continuous hard rock at shallow depth as well as rock outcrops. Some soils are easy to work independent of moisture conditions, other soils are only manageable at an adequate moisture status, in particular for manual cultivation or light machinery. Irregular soil depth, gravel and stones in the profile and rock outcrops, might prevent the use of heavy farm machinery. The soil...
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Diagnostic characteristics to indicate soil workability vary by type of management applied. Workability or ease of tillage depends on interrelated soil characteristics such as texture, structure, organic matter content, soil consistence/bulk density, the occurrence of gravel or stones in the profile or at the soil surface, and the presence of continuous hard rock at shallow depth as well as rock outcrops. Some soils are easy to work independent of moisture conditions, other soils are only manageable at an adequate moisture status, in particular for manual cultivation or light machinery. Irregular soil depth, gravel and stones in the profile and rock outcrops, might prevent the use of heavy farm machinery. The soil...
Ecologists increasingly use plot-scale data to inform research and policy related to regional and global environmental change. For soil chemistry research, scaling from the plot to the region is especially difficult due to high spatial variability at all scales. We used a hierarchical Bayesian model of plot-scale soil nutrient pools to predict storage of soil organic carbon (oC), inorganic carbon (iC), total nitrogen (N), and available phosphorus (avP) in a 7962-km2 area including the Phoenix, Arizona, USA, metropolitan area and its desert and agricultural surroundings. The Bayesian approach was compared to a traditional approach that multiplied mean values for urban mesic residential, urban xeric residential, nonresidential...
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Oxygen availability in soils is largely defined by drainage characteristics of soils. The determination of soil drainage classes is based on procedures developed at FAO (FAO 1995). These procedures take into account soil type, soil texture, soil phases and terrain slope. Apart from drainage characteristics, the soil quality of oxygen availability may be influenced by soil and terrain characteristics that are defined through the occurrence of specific soil phases. These include for the FAO 74 classification soil phases indicating phreatic conditions, and for the FAO 90 classification soil phases indicating respectively phreatic, anthraquic, inundic, or placic conditions. Soil qualities have been estimated for...
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Low pH leads to acidity related toxicities, e.g., aluminum, iron, manganese toxicities, and to various deficiencies, e.g., of phosphorus and molybdenum. Calcareous soils exhibit generally micronutrient deficiencies, for instance of iron, manganese, and zinc and in some cases toxicity of molybdenum. Gypsum strongly limits available soil moisture. Tolerance of crops to calcium carbonate and gypsum varies widely (FAO, 1990; Sys, 1993). Low pH and high calcium carbonate and gypsum are mutually exclusive. Acidity related toxicities such as aluminum toxicities and micro-nutrient deficiencies are accounted for respectively in SQ1, nutrient availability, and in SQ2, nutrient retention capacity. This soil quality SQ6 is...
Relatively few studies have examined the ecological and biogeochemical effects of livestock grazing in southeastern Utah. In this study, we evaluated how grazing has affected soil organic carbon and nitrogen to a depth of 50 cm in grasslands located in relict and actively-grazed sites in the Canyonlands physiographic section of the Colorado Plateau. We also evaluated differences in plant ground cover and the spatial distribution of soil resources. Results show that areas used by domestic livestock have 20% less plant cover and 100% less soil organic carbon and nitrogen compared to relict sites browsed by native ungulates. In actively grazed sites, domestic livestock grazing also appears to lead to clustered, rather...
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Relatively few studies have examined the ecological and biogeochemical effects of livestock grazing in southeastern Utah. In this study, we evaluated how grazing has affected soil organic carbon and nitrogen to a depth of 50 cm in grasslands located in relict and actively-grazed sites in the Canyonlands physiographic section of the Colorado Plateau. We also evaluated differences in plant ground cover and the spatial distribution of soil resources. Results show that areas used by domestic livestock have 20% less plant cover and 100% less soil organic carbon and nitrogen compared to relict sites browsed by native ungulates. In actively grazed sites, domestic livestock grazing also appears to lead to clustered, rather...
Soil organic C (SOC) and total N (TN) contents play a crucial role in sustaining agricultural production systems. Short-term (≤10-year) management effects on SOC and TN dynamics are often complex and variable. Three experiments were conducted to evaluate short-term tillage and cropping system effects on SOC and TN within the 0–30 cm soil depth across Iowa. The first experiment with no-tillage and chisel plowing treatments was established in 1994 on Clarion-Nicollet-Webster (CNW), Galva-Primghar-Sac (GPS), Kenyon-Floyd-Clyde (KFC), Marshall (M), and Otley-Mahaska-Taintor (OMT) soil associations under a corn (Zea mays L.)–soybean (Glycine max (L.) Merr.) rotation. The second experiment with no-tillage, strip-tillage,...
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These datasets represent a revised national scale estimate of wetland soil carbon stock assessments by improving representation of soil organic carbon densities. This assessment is based on a three-step approach to harmonize survey and point-based data for predicting soil organic carbon density from percent organic carbon alone (or percent organic matter, with conversion), when reliable dry bulk density information is not available. Given issues with survey-level extrapolation of soil pedons into discontinuous hydric soils, quantile, segmented data analysis provides a more accurate spatially explicit soil organic carbon density product. These modeled data leverage spatial and statistical distributions of soil organic...
Analyses of carbon isotope ratios (?13C) in soil organic matter (SOM) and soil respired CO2 provide insights into dynamics of the carbon cycle. ?13C analyses do not provide direct measures of soil CO2 efflux rates but are useful as a constraint in carbon cycle models. In many cases, ?13C analyses allow the identification of components of soil CO2 efflux as well as the relative contribution of soil to overall ecosystem CO2 fluxes. ?13C values provide a unique tool for quantifying historical shifts between C3 and C4 ecosystems over decadal to millennial time scales, which are relevant to climate change and land-use change issues. We identify the need to distinguish between ?13C analyses of SOM and those of soil CO2...
map background search result map search result map Biogeochemical and ecological impacts of livestock grazing in semi-arid southeastern Utah, USA Global Soil Organic Carbon Density in kg Carbon/m2 to 1 meter depth HWSD Soil Quality - Constraints on Tillage/Workability HWSD Global Soil Quality - Constraints on rooting conditions HWSD Soil Quality - Global constraints due to oxygen availability HWSD Global Soil Quality - Constraints on nutrient retention capacity HWSD Global Soil Quality - Constraints on nutrient availability HWSD Global Soil Quality - Constraints due to calcium carbonate and gypsum toxicities Harmonizing wetland soil organic carbon datasets to improve spatial representation of 2011 soil carbon stocks in the conterminous United States Biogeochemical and ecological impacts of livestock grazing in semi-arid southeastern Utah, USA Harmonizing wetland soil organic carbon datasets to improve spatial representation of 2011 soil carbon stocks in the conterminous United States HWSD Soil Quality - Constraints on Tillage/Workability HWSD Global Soil Quality - Constraints on rooting conditions HWSD Soil Quality - Global constraints due to oxygen availability HWSD Global Soil Quality - Constraints on nutrient retention capacity HWSD Global Soil Quality - Constraints on nutrient availability HWSD Global Soil Quality - Constraints due to calcium carbonate and gypsum toxicities Global Soil Organic Carbon Density in kg Carbon/m2 to 1 meter depth