scholarly journals Mechanisms of soil carbon storage in experimental grasslands

2007 ◽  
Vol 4 (5) ◽  
pp. 3829-3862
Author(s):  
S. Steinbeiss ◽  
V. M. Temperton ◽  
G. Gleixner
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Soil Solution ◽  
Carbon Storage ◽  
Amaranthus Retroflexus ◽  
Plant Litter ◽  
C3 Plants ◽  
Litter Input

Abstract. We investigated the fate of root and litter derived carbon into soil organic matter and dissolved organic matter in soil profiles, in order to explain unexpected positive effects of plant diversity on carbon storage. A time series of soil and soil solution samples was investigated at the field site of The Jena Experiment. In addition to the main biodiversity experiment with C3 plants, a C4 species (Amaranthus retroflexus L.) naturally labeled with 13C was grown on an extra plot. Changes in organic carbon concentration in soil and soil solution were combined with stable isotope measurements to follow the fate of plant carbon into the soil and soil solution. A split plot design with plant litter removal versus double litter input simulated differences in biomass input. After 2 years, the no litter and double litter treatment, respectively, showed an increase of 381 g C m−2 and 263 g C m−2 to 20 cm depth, while 71 g C m−2 and 393 g C m−2 were lost between 20 and 30 cm depth. The isotopic label in the top 5 cm indicated that 11 and 15% of soil organic carbon were derived from plant material on the no litter and the double litter treatment, respectively. Without litter, this equals the total amount of carbon newly stored in soil, whereas with double litter this corresponds to twice the amount of stored carbon. Our results indicate that litter input resulted in lower carbon storage and larger carbon losses and consequently accelerated turnover of soil organic carbon. Isotopic evidence showed that inherited soil organic carbon was replaced by fresh plant carbon near the soil surface. Our results suggest that primarily carbon released from soil organic matter, not newly introduced plant organic matter, was transported in the soil solution and contributed to the observed carbon storage in deeper horizons.

Maximum soil organic matter decomposition along temperature gradient in Colombian topsoils: Dry Forests

2021 ◽  
Author(s):  
Gerardo Ojeda ◽  
Hernando García ◽  
Susanne Woche ◽  
Jorg Bachmann ◽  
Georg Guggenberger ◽  
...  
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Organic Carbon ◽  
Temperature Gradient ◽  
Soil Organic Carbon ◽  
Soil Respiration ◽  
Maximum Rate ◽  
Field Capacity ◽  
Total Carbon ◽  
Som Decomposition

<p><strong>Contextualization</strong>: In 2011, it was published a curious conundrum, which forms the basis of the present study: why, when organic matter is thermodynamically unstable, does it persist in soils, sometimes for thousands of years? The question challenges the idea that the recalcitrant or labile character of soil organic matter (SOM) is a sufficient argument to ensure SOM persistence. Temperature could play an important role in SOM decomposition, especially in tropics. Particularly, tropical dry forest (TDF) represents an important ecosystem with unique biodiversity and fertile soils in Colombia. At present, the increase in population density and consequently, in the demands of energy and arable land, have led to its degradation.</p><p> </p><p><strong>Knowledge gap</strong>: Although the mentioned question was formulated several years ago, it has still to be answered, hence limiting the development of new soil organic carbon (SOC) models or the quantification of its ecosystem services. A key point, in terms of soil carbon storage, is to determine the maximum rate of CO<sub>2</sub> emissions from soils (Rmax). Traditionally, it is considered that Rmax occurs at the 50% of field capacity. Unfortunately, information about the environmental conditions under which this maximum occurs is scarce.</p><p><strong> </strong></p><p><strong>Purpose</strong>: The main objectives of this study were: (a) determine the maximum rate of soil respiration or CO<sub>2</sub> emissions from soil in TDF soils and (b) to estimate the main environmental drivers of maximum SOM decomposition along a temperature gradient (20°, 30°, 40°C) in incubated soils.</p><p><strong> </strong></p><p><strong>Methodology</strong>: Soils pertained to permanent plots were sampled in six different TDF of Colombia. The evolution of CO<sub>2</sub> emissions (monitored by an infrared gas analyser), relative humidity and soil temperature were recorded in time on incubated soils samples. Temperature was maintained constant at 20°C, 30°C and 40°C during soil incubations under soil drying conditions. Additionally, elemental composition (Fe, Ca, O, Al, Si, K, Mg, Na) of SOM and chemical composition of soil organic carbon (SOC: aromatic-C, O-alkyl-C, Aliphatic-C, Phenolic and Ketonic-C) were determined by X-ray photoelectron spectroscopy (XPS).</p><p><strong> </strong></p><p><strong>Results and conclusions</strong>: The majority of TDF soil samples (90.7%) presented that its peak of CO<sub>2</sub> emissions occurs at soil-water contents higher than saturation (0 MPa), at 20°, 30° and 40°C. Clearly, to consider that the maximum soil respiration rate could be observed at the 50% of field capacity, underestimated the real maximum value of carbon mineralization (48-68%.) Globally, increases in the Rmax values corresponded to increases in electrical conductivity, soil desorption rates, total carbon and nitrogen contents, and decreases in bulk density (BD) and aggregate stability. Taking into account the temperature gradient, increments in calcium and aromatic carbon contents corresponded to decrements in Rmax values but only at 30°C and 40°C, respectively. Some authors indicated that at high soil moisture contents, iron reduction could be release protected carbon. However, no significant relation between Fe and Rmax was observed. Consequently, physical and chemical properties related to SOM accessibility and decomposability by microbial activity, were the main drivers and controls of maximum SOM decomposition rates.</p>

scholarly journals From Laboratory to Proximal Sensing Spectroscopy for Soil Organic Carbon Estimation—A Review

2020 ◽  
Vol 12 (2) ◽  
pp. 443 ◽  
Author(s):  
Theodora Angelopoulou ◽  
Athanasios Balafoutis ◽  
George Zalidis ◽  
Dionysis Bochtis
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Management Practices ◽  
Near Infrared ◽  
Wavelength Region ◽  
Soil Condition ◽  
Short Wave ◽  
Proximal Sensing

Rapid and cost-effective soil properties estimations are considered imperative for the monitoring and recording of agricultural soil condition for the implementation of site-specific management practices. Conventional laboratory measurements are costly and time-consuming, and, therefore, cannot be considered appropriate for large datasets. This article reviews laboratory and proximal sensing spectroscopy in the visible and near infrared (VNIR)–short wave infrared (SWIR) wavelength region for soil organic carbon and soil organic matter estimation as an alternative to analytical chemistry measurements. The aim of this work is to report the progress made in the last decade on data preprocessing, calibration approaches, and system configurations used for VNIR-SWIR spectroscopy of soil organic carbon and soil organic matter estimation. We present and compare the results of over fifty selective studies and discuss the factors that affect the accuracy of spectroscopic measurements for both laboratory and in situ applications.

Changes in soil organic carbon and nitrogen after 47 years with different tillage, stubble and fertiliser management in a Vertisol of north-eastern Australia

Soil Research ◽  
2020 ◽  
Vol 58 (4) ◽  
pp. 346
Author(s):  
K. L. Page ◽  
R. C. Dalal ◽  
S. H. Reeves ◽  
W. J. Wang ◽  
Somasundaram Jayaraman ◽  
...  
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Management Practices ◽  
Crop Residues ◽  
Residue Management ◽  
Eastern Australia ◽  
North Eastern ◽  
Over Time

No-till (NT) farming has been widely adopted to assist in reducing erosion, lowering fuel costs, conserving soil moisture and improving soil physical, chemical and biological characteristics. Improvements in soil characteristics are often driven by the greater soil organic matter accumulation (as measured by soil organic carbon (SOC)) in NT compared to conventional tillage (CT) farming systems. However, to fully understand the effect of NT it is important to understand temporal changes in SOC by monitoring over an extended period. We investigated the long-term effect of NT and stubble retention (SR) on changes in SOC and total soil nitrogen (STN) using results from an experiment that has been running for 50 years in a semi-arid subtropical region of north-eastern Australia. In this experiment, the effects of tillage (CT vs NT), residue management (stubble burning (SB) vs SR), and nitrogen (N) fertiliser (0 and 90 kg-N ha–1) were measured in a balanced factorial experiment on a Vertisol (Ustic Pellusert). The use of NT, SR and N fertiliser generally improved SOC (by up to 12.8%) and STN stocks (by up to 31.7%) in the 0–0.1 m layer relative to CT, SB and no N fertiliser, with the greatest stocks observed where all three treatments were used in combination. However, declines in SOC (up to 20%) and STN (up to 25%) occurred in all treatments over the course of the experiment, indicating that changes in management practices were unable to prevent a loss of soil organic matter over time in this farming system. However, the NT and SR treatments did lose less SOC than CT and SB treatments, and SR also reduced STN loss. The δ13C analysis of samples collected in 2008 and 2015 highlighted that crop residues have significantly contributed to SOC stocks at the site and that their contribution is increasing over time.

scholarly journals Spatial Distribution of Soil Organic Matter and Soil Organic Carbon Stocks in Semi-Arid Area of Northeastern Syria

2019 ◽  
Vol 10 (12) ◽  
pp. 415-432
Author(s):  
Hussam Hag Husein ◽  
Mohammad Mousa ◽  
Wahib Sahwan ◽  
Rupert Bäumler ◽  
Bernhard Lucke
Keyword(s):  
Organic Matter ◽  
Spatial Distribution ◽  
Soil Organic Matter ◽  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Carbon Stocks ◽  
Arid Area ◽  
Soil Organic Carbon Stocks ◽  
Semi Arid

scholarly journals Assessing soil carbon and soil quality for sustainable agricultural systems in tropical hillslope soils using spectroscopic methods

2017 ◽  
Author(s):  
◽  
Bunjirtluk Jintaridth
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Soil Quality ◽  
Management Practices ◽  
Soil Management ◽  
Agricultural Systems ◽  
Wide Range ◽  
The World

Soil quality is a concept that integrates physical, chemical, and biological components and processes of soil across landscapes. Identifying and developing appropriate methods to quantify and assess changes in soil quality are necessary for evaluating soil degradation and improving management practices. Many parameters that are associated with soil quality depend on soil organic matter (SOM) levels and composition. The objectives of this research were to: 1) conduct a literature review of soil quality assessment techniques to evaluate soil quality across a wide-range of environments and agricultural practices; 2) determine if some standard soil sampling and analytical protocols could be identified or developed to enhance soil quality comparisons across a wide range of environments around the world; and 3) assess the efficacy of spectroscopic-based (i.e. near-infrared, mid-infrared, and visible range) analytical methods to evaluate soil organic matter fractions and soil quality. To assess soil quality for sustainable agricultural systems in hillslope soils using spectroscopic methods, surface soil samples (0-20 cm) were collected from hillslope agricultural sites in Bolivia, the Philippines and Indonesia which had differences in length of fallow, levels of soil degradation, and cultivation by landscape position. To determine the efficacy of spectroscopic-based on visible range, the use of the potassium permanganate test (MnOxC) for active organic carbon was studied. The MnOxC test was generally responsive to a range of fallow lengths among different agricultural fields and communities in Umala Municipality in Bolivia. A major objective of fallowing agricultural fields in this region is to restore soil fertility in the field after cropping. This general increase in MnOxC with increased length fallowing may be due to inputs of residue and roots from regrowth of native vegetation after cropping in fallowed areas and possible manure inputs from sheep that generally graze these fallow areas. In addition, higher concentrations of MnOxC were generally observed in non-degraded soil compared to that of degraded soil in all sampled communities in Cochabamba, Bolivia. Comparisons of soil quality among agroforestry and nonagroforestry sites were studied near Bogor, Indonesia. Both agroforestry and nonagroforestry sites had been managed with different types and rates (low, medium, and high) of amendments including manure, compost and chemical fertilizer. Soil MnOxC was generally higher with increasing amounts of added animal manure and in agroforestry areas compared to that of non-agroforestry areas. A set of soil samples was collected along a hill-slope transect from the top to the bottom of agricultural valley on Mindanao Island in the Philippines. The transect across the landscape was divided into summit, shoulder, backslope, footslope and toeslope landscape positions. Soil MnOxC from cultivated fields areas at each landscape position were generally lower than noncultivated areas at similar landscape positions. Among the non-cultivated sites, soil MnOxC was the highest at the summit position and the lowest at the backslope positions while soil MnOxC among cultivated sites were relatively similar across the hill-slope transect. This comparison of the use of the soil MnOxC test to determine changes in active C among a wide range of environmental conditions, cropping systems and soil management practices among agroecosystems with hillslopes in tropical countries around the world indicates that the soil MnOxC test is a sensitive indicator to assess changes in active C with changes in crop and soil management. Several advantages to using this procedure include its ease of use that requires a minimal of training for the field method, its low relative cost and growing research results that facilitate interpretation of the test results. Therefore, this method has potential for supporting management decisions, and sustainable management of agricultural systems in tropical hillslope ecosystems. The ability of visible/near-infrared (VNIR) spectroscopy to estimate soil organic carbon and carbon fractions from diverse soils in tropical hillslope agroecosystems around the world that were under different soil management and cropping systems was evaluated in this research. It was shown that VNIR spectroscopy could be an effective technique to estimate SOC and soil organic carbon fractions for a wide range of soils from tropical hillslope agroecosystems around the world. Several potential advantages of use of VNIR compared to conventional soil testing methods in developing countries are that it may allow for simultaneous evaluation of several soil properties and it can be done rapidly and possibly in the field. Diffuse Reflectance Fourier Transform Infrared Spectroscopy (DRIFT) is considered to be one of the most sensitive infrared techniques for analyzing the structural composition of soil organic matter. The benefit of the DRIFT technique is the ability to characterize the functional group composition of heterogeneous materials with minimal sample preparation. Results showed that this method can be used to characterize the functional groups of heterogeneous soil organic materials and it may be a more direct method to determine changes in soil organic matter and soil quality caused by soil management practices than several other chemical and spectral techniques. The high resolution of the spectra and quantitative estimations of functional groups can be used to analyze soil organic carbon composition. Therefore, in future work this technique has great potential to be an accurate and simple method for helping to understand the changes in the composition of soil organic carbon due to soil organic management practices and to estimate changes in soil quality resulting from those practices in these hillslope agroecosystems.

scholarly journals Characteristics and Driving Mechanism of Soil Organic Carbon Content in Farmland of Beijing Plain: Implication for the Fate of Engineered Polymers in Soil

2019 ◽  
Vol 2019 ◽  
pp. 1-10
Author(s):  
Lanlan Zhang ◽  
Zhen Li ◽  
Shiwen Zhang ◽  
Shasha Xia ◽  
Hongguang Zou ◽  
...  
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Carbon Content ◽  
Organic Fertilizer ◽  
Driving Mechanism ◽  
Organic Carbon Content ◽  
Beijing Plain ◽  
Significant Difference

Soil organic matter (SOM), as a kind of natural polymers, affects the migration and transport of ions and particles in soil system due to its surface characteristics and interaction and then causes significant changes in soil quality such as soil fertility loss and pollutant transfer. It is of great importance to study the temporal and spatial evolution of soil organic matter and its driving mechanism for soil health management. This study aims to fully reveal the evolution characteristics and driving mechanism of soil organic carbon (SOC) in farmland of the Beijing plain based on a six-year site monitoring. According to the research results, there is a significant difference in the overall soil organic content during the 6-year period. The temporal stability of SOC is moderate, and it is inversely proportional to SOC content in terms of spatial distribution. SOC content increases as organic fertilizer input rises, and an extra unit (15 kg·ha−1) of organic fertilizer input leads to an increase of 0.057 g·kg−1 in SOC content. The soil with higher clay content exhibits higher SOC content. The organic carbon content in different soil texture types increases with time, and there is a significant difference between the increases in medium loam and light loam. The grain field plantation system exhibited declining SOC content, while the protected vegetable fields, open vegetable fields, and orchards all showed an increase in SOC content. According to our results, the SOC content of farmland in the plain areas of Beijing is largely dependent on the input of organic carbon if other conditions remain unchanged or exhibit insignificant changes.

scholarly journals Critical Analysis of the van Bemmelen Conversion Factor used to Convert Soil Organic Matter Data to Soil Organic Carbon Data: Comparative Analyses in a UK Loamy Sand Soil

2016 ◽  
Vol 6 (1) ◽  
pp. 35-44 ◽  
Author(s):  
Lee Heaton ◽  
Michael A. Fullen ◽  
Ranjan Bhattacharyya
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Conversion Factor ◽  
Soil Samples ◽  
Loamy Sand ◽  
Soil C ◽  
Loamy Sand Soil ◽  
Dry Combustion

Converting soil organic matter (SOM) data to soil organic carbon (SOC) data usually uses the van Bemmelen factor of 0.58 (or in reverse its reciprocal of 1.724) as a universal conversion factor. The accuracy of this conversion factor has been questioned. Under the Kyoto Protocol (1997) dry combustion is recommended to provide reproducible analyses to measure soil carbon stocks. However, dry combustion equipment is expensive and entails high maintenance. For rapid and inexpensive measurements, loss-on-ignition (LOI) is often used. A total of 278 loamy sand topsoil (0-5 cm depth) samples were taken during three soil sampling sessions (9 January 2007, 22 January 2009 and 10 October 2011) from runoff plots, splash erosion plots and grassed/cultivated plots on the Hilton Experimental Site, Shropshire, UK. A total of 124 soil samples were collected from both runoff and splash plots in both 2007 and 2009 (Bhattacharyya et al., 2011a). Some 22 of the collected samples in 2011 were from grassland (Ah horizon) and eight from cultivated soils (Ap horizon). Homogenized soil samples were split and SOM was determined on oven-dried samples by LOI and total SOC was determined by dry combustion. A conversion factor of 0.845 was used to obtain SOC from total soil C, following Rawlins et al. (2011). Results showed strong associations (R² = 0.70, P 0.001, n = 278) between SOM and SOC data. For all data, SOM to SOC conversion factors varied between 0.36-0.98, with a mean value of 0.66 (SD = 0.105). The mean values of the conversion factor were 0.64, 0.69 and 0.56, respectively, for the samples collected in 2007, 2009 and 2011. Results indicate the van Bemmelen factor (0.58) is a reasonable predictor, but both temporal and spatial variations occur around it within a specific soil type. Thus, caution should be exercised in SOM/SOC data conversions using the van Bemmelen factor.

scholarly journals Soil organic matter dynamics under different land use in grasslands in Inner Mongolia (northern China)

2014 ◽  
Vol 11 (18) ◽  
pp. 5103-5113 ◽  
Author(s):  
L. Zhao ◽  
W. Wu ◽  
X. Xu ◽  
Y. Xu
Keyword(s):  
Land Use ◽  
Organic Matter ◽  
Soil Organic Matter ◽  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Northern China ◽  
Organic Carbon Content ◽  
Groundwater Supply ◽  
Aliphatic Carbon ◽  
Degraded Grassland

Abstract. We examined bulk soil properties and molecular biomarker distributions in surface soils from Inner Mongolian grasslands in order to understand the responses of soil organic matter to different land use. A total of 16 soils were collected from severely degraded grassland by overgrazing (DG), native grassland without apparent anthropogenic disturbance (NG), groundwater-sustaining grassland (GG) and restored grassland from previous potato cropland (RG). Compared to NG, soil organic carbon content was lower by 50% in DG, but higher by six-fold in GG and one-fold in RG. The δ13C values of soil organic carbon were –24.2 ± 0.6‰ in DG, –24.9 ± 0.6‰ in NG, –25.1 ± 0.1‰ in RG and –26.2 ± 0.6‰ in GG, reflecting different degradation degrees of soil organic matter or different water use efficiencies. The soils in DG contained the lowest abundance of aliphatic lipids (n-alkanes, n-alkanols, n-alkanoic acids, ω-hydroxylalkanoic acids and α-hydroxyalkanoic acids) and lignin-phenols, suggesting selective removal of these biochemically recalcitrant biomarkers with grassland degradation by microbial respiration or wind erosion. Compared to NG, the soils in GG and RG increased ω-hydroxylalkanoic acids by 60–70%, a biomarker for suberin from roots, and increased α-hydroxylalkanoic acids by 10–20%, a biomarker for both cutin and suberin. Our results demonstrate that the groundwater supply and cultivation–restoration practices in Inner Mongolian grasslands not only enhance soil organic carbon sequestration, but also change the proportions of shoot- versus root-derived carbon in soils. This finding has important implications for the global carbon cycle since root-derived aliphatic carbon has a longer residence time than the aboveground tissue-derived carbon in soils.

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