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Measuring and modelling continuous quality distributions of soil organic matter
S. Bruun,G. I. ?gren,B. T. Christensen,L. S. Jensen
Biogeosciences Discussions , 2009,
Abstract: An understanding of the dynamics of soil organic matter (SOM) is important for our ability to develop management practices that preserve soil quality and sequester carbon. Most SOM decomposition models represent the heterogeneity of organic matter by a few discrete compartments with different turnover rates, while other models employ a continuous quality distribution. To make the multi-compartment models more mechanistic in nature, it has been argued that the compartments should be related to soil fractions actually occurring and having a functional role in the soil. In this paper, we make the case that fractionation methods that can measure continuous quality distributions should be developed, and that the temporal development of these distributions should be incorporated into SOM models. The measured continuous SOM quality distributions should hold valuable information not only for model development, but also for direct interpretation. Measuring continuous distributions requires that the measurements along the quality variable are so frequent that the distribution is approaching the underlying continuum. Continuous distributions leads to possible simplifications of the model formulations, which considerably reduce the number of parameters needed to describe SOM turnover. A general framework for SOM models representing SOM across measurable quality distributions is presented and simplifications for specific situations are discussed. Finally, methods that have been used or have the potential to be used to measure continuous quality SOM distributions are reviewed. Generally, existing fractionation methods have to be modified to allow measurement of distributions or new fractionation techniques will have to be developed. Developing the distributional models in concert with the fractionation methods to measure the distributions will be a major task. We hope the current paper will help spawning the interest needed to accommodate this.
Measuring the Complexity of Continuous Distributions  [PDF]
Guillermo Santamaría-Bonfil,Nelson Fernández,Carlos Gershenson
Physics , 2015,
Abstract: We extend previously proposed measures of complexity, emergence, and self-organization to continuous distributions using differential entropy. This allows us to calculate the complexity of phenomena for which distributions are known. We find that a broad range of common parameters found in Gaussian and scale-free distributions present high complexity values. We also explore the relationship between our measure of complexity and information adaptation.
The Unified North American Soil Map and its implication on the soil organic carbon stock in North America  [PDF]
S. Liu,Y. Wei,W. M. Post,R. B. Cook
Biogeosciences Discussions , 2012, DOI: 10.5194/bgd-9-15175-2012
Abstract: The Unified North American Soil Map (UNASM) was developed to provide more accurate regional soil information for terrestrial biosphere modeling. The UNASM combines information from state-of-the-art US STATSGO2 and Soil Landscape of Canada (SLCs) databases. The area not covered by these datasets is filled with the Harmonized World Soil Database version 1.1 (HWSD1.1). The UNASM contains maximum soil depth derived from the data source as well as seven soil attributes (including sand, silt, and clay content, gravel content, organic carbon content, pH, and bulk density) for the top soil layer (0–30 cm) and the sub soil layer (30–100 cm) respectively, of the spatial resolution of 0.25° in latitude and longitude. There are pronounced differences in the spatial distributions of soil properties and soil organic carbon between UNASM and HWSD, but the UNASM overall provides more detailed and higher-quality information particularly in Alaska and Central Canada. To provide more accurate and up-to-date estimate of soil organic carbon stock in North America, we incorporated Northern Circumpolar Soil Carbon Database (NCSCD) into the UNASM. The estimate of total soil organic carbon mass in the upper 100 cm soil profile based on the improved UNASM is 347.70 Pg, of which 24.7% is under trees, 14.2% is under shrubs, and 1.3% is under grasses and 3.8% under crops. This UNASM data will provide a resource for use in land surface and terrestrial biogeochemistry modeling both for input of soil characteristics and for benchmarking model output.
Effect of Continuous Agriculture of Grassland Soils of the Argentine Rolling Pampa on Soil Organic Carbon and Nitrogen  [PDF]
Luis A. Milesi Delaye,Alicia B. Irizar,Adrián E. Andriulo,Bruno Mary
Applied and Environmental Soil Science , 2013, DOI: 10.1155/2013/487865
Abstract: Long-term soil organic carbon (SOC) and soil organic nitrogen (SON) following cultivation of grassland soils (100/120-year tillage (T) + 20/30-year no tillage (NT)) of the Rolling Pampa were studied calibrating the simple AMG model coupled with the natural 13C abundance measurements issued from long-term experiments and validating it on a data set obtained by a farmer survey and by long-term NT experiments. The multisite survey and NT trials permitted coverage of the history of the 140 years with agriculture. The decrease in SOC and SON storage that occurred during the first twenty years by a loss through biological activity was 27% for SOC and 32% for SON. The calibrated model described the SOC storage evolution very well and permitted an accurate simultaneous estimation of their three parameters. The validated model simulated well SOC and SON evolution. Overall, the results analyzed separately for the T and NT period indicated that the active pool has a rapid turnover (MRT ~9 and 13 years, resp.) which represents 50% of SOC in the native prairie soil and 20% of SOC at equilibrium after NT period. NT implementation on soils with the highest soil organic matter reserves will continue to decrease (17%) for three decades later under current annual addition. 1. Introduction It is well established that grassland soils, particularly Mollisols, originally rich in soil organic matter (SOM), rapidly lose important quantities of carbon (C) and nitrogen (N) after cultivation [1–10]. Long-term cultivation effects on soil organic carbon (SOC) and soil organic nitrogen (SON) provide necessary information to evaluate the sustainability of cropping systems and their effects on the environment. Assessment of SOM is a valuable step towards identifying the overall quality of a soil [11–13]. The agriculture of the Argentine Rolling Pampa consists of a sequence of arable crops for 100 to 120 years followed by two or three decades of cropping under no tillage (NT). Before the 1970s, maize (Zea mays L.), wheat (Triticum aestivum L.), and flax (Linun usitatisinum L.) were alternated with pastures for beef production. Since the 1970s, largely due to economic reasons, there has been an important increase in the area under arable crops, with the cropped area increasing relative to the pasture area at an annual rate of 4% [14]. This resulted in an increase in tillage intensities. Furthermore, soybean was often double cropped with wheat (W/S) in the same year. Fertilizer use was relatively restricted until 1992 (<5?kg?N?ha?1a?o?1) [7, 15–17], and liming is not practiced by
Effects of Sod Cultivation in Orchard on Distributions of Soil Aggregates and Soil Organic Carbon of Aggregates
生草栽培对果园土壤团聚体及其有机碳分布的影响

WANG Yi-xiang,WENG Bo-qi,HUANG Yi-bin,WANG Cheng-ji,YE Jing,
王义祥
,翁伯琦,黄毅斌,王成己,叶菁

热带亚热带植物学报 , 2012,
Abstract: The effects of sod cultivation in orchard on distribution of organic carbon in soil aggregates were investigated, which located in Yuchi Village, Youxi Xian, Fujian Province. The results showed that compared with downslope and landings clean tillage orchards, the proportion of >0.25 mm water-stable aggregate (R0.25), mean weight diameter (MWD), and geometric mean diameter (GWD) of soil aggregate at 0-20 cm soil layer in sod cultivation orchard increased by 3.78%-5.90%, 16.82%-20.94%, 5.86%-50.31% and 3.81%-13.82%, 13.33%- 19.95%, 7.50%-60.63%, and the fractal dimension decreased by 1.54%-2.35% and 1.09%-9.64%, respectively. The sod cultivation could improve proportion of organic carbon storage in large aggregates (>2 mm) to total organic carbon at 0-20 cm soil layer. Therefore, the sod cultivation was beneficial to improve stability of soil aggregate, and could enhance the protection of organic carbon and carbon sink in soil.
Identification of Soil Management Factors from Spatially Variable Soil Properties of Coastal Plain Sands in Southeastern Nigeria  [PDF]
Jude C. Obi, Bassey T. Udoh
Open Journal of Soil Science (OJSS) , 2011, DOI: 10.4236/ojss.2011.12004
Abstract: Variability in soil properties is a critical element across wide areas of researches especially in several aspects of agriculture and environment including sewage disposal and global climate change. Particle size fraction (sand, silt, and clay), effective cation exchange capacity, base saturation, pH, organic carbon, total nitrogen, carbon nitrogen ratio, available phosphorus, exchangeable bases (calcium, magnesium, sodium, potassium) and acidity are frequently used in agriculture for soil management. The objective of this study therefore was to identify soil management factors from these set of 15 soil properties and spatial distribution of representative soil management properties. The study was carried out in the University of Uyo Teaching and Research Farm measuring 8.19 hectares in University of Uyo Annex, Uyo in Akwa Ibom State of Nigeria. Nine and ten traverses were made horizontally and vertically respectively at 40 meters intervals. A total of 58 soil samples were collected at 0 - 15 cm depth on the grid nodes of the traverses. Particle size distributions, exchangeable bases and acidity, effective cation exchange capacity (ECEC), available phosphorus (avail. P), base saturation (BS), organic carbon, total nitrogen, carbon nitrogen ratio (CNR) and pH of the samples were determined in the laboratory. Coefficient of variation indicated that 26.6% of the soil properties (sand content, pH, CNR and sodium) were least variable, 40.1% comprising silt, clay contents, ECEC, base saturation, phosphorus and magnesium were moderately. Whereas 33.3% of the soil properties comprising clay content, organic carbon, total nitrogen, exchangeable Ca, K and acidity (i.e.) were highly variable. There were significant correlation (p < 0.05) in 26.6% of the soil properties, the strongest negative significant (p < 0.01) correlations were between sand and clay (r = –0.85), exchangeable acidity and base saturation (r = –0.85), whereas the strongest positive significant correlations were between ECEC and Ca (r = 0.80), Ca and BS (r = 0.74), organic carbon and total nitrogen (r = 0.80). Principal component analysis indicated the existence of six factors including mineralogical or weathering, soil organic matter, cation exchange activity, soil texture, and dispersion and soil phosphorus based on either management or pedological considerations. Semivariance statistics showed that sand and clay contents, ECEC, BS and total N were moderately (≥25.7% ≤47.3%), while silt content, pH, organic carbon, CNR, avail. P, exchangeable Ca, Mg, Na and acidity (≥0.18% ≤22.8%) were
Estimation of soil organic carbon storage and the characteristic of carbon spatial distributions in karst area, Chongqing, China
重庆岩溶区土壤有机碳库的估算及其空间分布特征

倪九派,袁道先,谢德体,魏朝富
生态学报 , 2009,
Abstract: The estimation of soil organic carbon storage is very important to the research of carbon cycle. The soil organic carbon density and storage of Chongqing karst area was estimated, using the data of 1412 soil profile from the second soil survey of China and formulating fertilization for soil conditions in 2007. Integrating the soil map, land use status quo map and district map of Chongqing karst area, the index of soil organic abundance were introduced and the characteristic of soil organic distribution in different soil and landscapes were analyzed. Results showed: the storage of soil organic carbon of Chongqing karst area to the depths of 20 cm and 100 cm were 1.43×1011 kg and 3.29×1011 kg, respectively. Carbon density of 20 cm soil was 1.26-7.20 kg m-2, and carbon density of 100 cm soil was 1.43-25.72 kg m-2. The amount of soil organic carbon varied significantly at different soils and landscapes, the index of soil organic abundance of soils and landscapes at 20 cm depth ranged from 0.73-1.74 and 0.39-1.20, and that at 100 cm depth changed between 0.32-3.00 and 0.46-1.70, respectively. The soil organic carbon storage of unit area at 20 cm depth was above the average level of China, but that at 100 cm depth was below the average level of China in Chongqing karst area. In a word, the soil organic carbon storage was relatively indigent in Chongqing karst area.
Models of soil organic matter decomposition: the SoilR package, version 1.0
C. A. Sierra, M. Müller,S. E. Trumbore
Geoscientific Model Development (GMD) & Discussions (GMDD) , 2012, DOI: 10.5194/gmd-5-1045-2012
Abstract: Soil organic matter decomposition is a very important process within the Earth system because it controls the rates of mineralization of carbon and other biogeochemical elements, determining their flux to the atmosphere and the hydrosphere. SoilR is a modeling framework that contains a library of functions and tools for modeling soil organic matter decomposition under the R environment for computing. It implements a variety of model structures and tools to represent carbon storage and release from soil organic matter. In SoilR, organic matter decomposition is represented as a linear system of ordinary differential equations that generalizes the structure of most compartment-based decomposition models. A variety of functions is also available to represent environmental effects on decomposition rates. This document presents the conceptual basis for the functions implemented in the package. It is complementary to the help pages released with the software.
Spatial distribution of soil organic carbon stocks in France  [PDF]
M. P. Martin,M. Wattenbach,P. Smith,J. Meersmans
Biogeosciences Discussions , 2010, DOI: 10.5194/bgd-7-8409-2010
Abstract: Soil organic carbon plays a major role in the global carbon budget, and can act as a source or a sink of atmospheric carbon, whereby it can influence the course of climate change. Changes in soil organic soil stocks (SOCS) are now taken into account in international negotiations regarding climate change. Consequently, developing sampling schemes and models for estimating the spatial distribution of SOCS is a priority. The French soil monitoring network has been established on a 16 km × 16 km grid and the first sampling campaign has recently been completed, providing circa 2200 measurements of stocks of soil organic carbon, obtained through an in situ composite sampling, uniformly distributed over the French territory. We calibrated a boosted regression tree model on the observed stocks, modelling SOCS as a function of other variables such as climatic parameters, vegetation net primary productivity, soil properties and land use. The calibrated model was evaluated through cross-validation and eventually used for estimating SOCS for the whole of metropolitan France. Two other models were calibrated on forest and agricultural soils separately, in order to assess more precisely the influence of pedo-climatic variables on soil organic carbon for such soils. The boosted regression tree model showed good predictive ability, and enabled quantification of relationships between SOCS and pedo-climatic variables (plus their interactions) over the French territory. These relationship strongly depended on the land use, and more specifically differed between forest soils and cultivated soil. The total estimate of SOCS in France was 3.260 ± 0.872 PgC for the first 30 cm. It was compared to another estimate, based on the previously published European soil organic carbon and bulk density maps, of 5.303 PgC. We demonstrate that the present estimate might better represent the actual SOCS distributions of France, and consequently that the previously published approach at the European level greatly overestimates SOCS.
Models of soil organic matter decomposition: the SOILR package, version 1.0
C. A. Sierra,M. Müller,S. E. Trumbore
Geoscientific Model Development Discussions , 2012, DOI: 10.5194/gmdd-5-993-2012
Abstract: Organic matter decomposition is a very important process within the Earth System because it controls the rates of mineralization of carbon and other biogeochemical elements, determining their flux to the atmosphere and the hydrosphere. SOILR is a modeling framework that contains a library of functions and tools for modeling soil organic matter decomposition under the R environment for computing. It implements a variety of model structures and tools to represent carbon storage and release from soil organic matter. In SOILR organic matter decomposition is represented as a linear system of ordinary differential equations that generalizes the structure of most compartment-based decomposition models. A variety of functions is also available to represent environmental effects on decomposition rates. This document presents the conceptual basis for the functions implemented in the package. It is complementary to the help pages released with the software.
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