Analysis Of Soil Organic Carbon Research Articles

Recovery status of coastal vegetation in Mozambique: Insights from floristic composition and soil organic carbon analysis

The growing demand for land for slash-and-burn cultivation, driven by human population growth, has led to the creation of scattered cultivated fields and a mosaic of fallow areas in various stages of regeneration. While tropical forests have demonstrated the ability to rebound regarding tree species diversity and forest structure following disturbances, the extent of recovery in coastal vegetation in southern Africa remains uncertain and poorly understood. To address this knowledge gap, our study collected biophysical data from smallholder fields, fallow land, and forests to evaluate the structure and functioning of coastal vegetation in Gaza province, southern Mozambique. We established 90 sample plots of 0.1 ha each at different stages of plant succession using opportunistic sampling approach. Within these plots, we recorded the diameter at breast height, total height, and species name of all trees and shrubs. Litter and soil samples were collected in 1 m² quadrats embedded within the main plot. Our findings indicate a high capacity for regeneration following the disturbance caused by slash-and-burn cultivation. Species composition varied significantly across different stages of succession, with 52 species identified in forests (FL), 34 in old fallow (OF), 29 in middle fallow (MF), 28 in initial fallow (IF), and 15 in cropland (CL). Richness and diversity increased over time after the practice of slash-and-burn cultivation, with a noticeable enhancement from the initial fallow stage. We observed a gradual recovery of soil carbon stocks in young fallow areas, while litter biomass decreased throughout the recovery phase of the fallow lands. Our study highlights that areas abandoned after agriculture can regenerate in terms of structure, floristic composition, and tree carbon content.

Carbon dioxide fluxes and soil carbon storage in relation to long‐term grazing and no grazing in Icelandic semi‐natural grasslands

AbstractQuestionWhat is the effect of long‐term grazing and no grazing (NG) on carbon dioxide flux and soil carbon storage in Icelandic semi‐natural grasslands.LocationThree farms, with known history of land use, in W Iceland.MethodsOn each farm, we located an intensively and an extensively grazed site, which both had been constantly grazed for centuries, and a parallel site with no grazing for over 50 years. We measured net ecosystem exchange (NEE), ecosystem respiration and normalized difference vegetation index on a regular basis over the growing season. Samples were taken from 60 cm deep soil profiles for analysis of soil organic carbon (SOC).ResultsThe grazed sites showed significantly more negative NEE than the NG sites, indicating more carbon dioxide uptake on the grazed sites compared to the NG sites. The normalized difference vegetation index was also significantly higher on the grazed sites. On all farms, the total SOC content was higher in the grazed sites than in the parallel NG sites.ConclusionsThe study indicates that cessation of grazing decreases productivity and carbon dioxide uptake in a semi‐natural grassland in Iceland, as well as SOC content in the soil. Historically, all the NG sites in the study had the same grazing history as the continuously grazed sites until grazing exclusion. The measured lower SOC on the NG sites seems to indicate that, without grazing, SOC is lost with time and/or grazing is needed to maintain SOC in these grasslands.

Forest carbon stock variation with altitude in bolale natural forest, Western Ethiopia

This study was initiated to assess forest carbon stock variation with altitude. A systematic sampling technique was used to select sample plots. A total of 36 (12 plots from each altitude class) square plots with size of 20 m × 20 m were obtained. Diameter at breast height (DBH) and height of individual trees of DBH > 5 cm were measured from all the selected sample plots. A total of 216 soil samples, 108 for analysis of soil organic carbon (SOC) fraction (% C), and 108 for bulk density determination (BD), were collected. Altitude had a significant effect on above and belowground tree biomass, and litter carbon stock, but not on deadwood, and soil organic carbon stock. The aboveground and belowground biomass and litter carbon were higher at lower altitudes, which were attributed to higher biomass production due to higher photosynthesis and higher net primary production. Soil organic carbon varied significantly with depth. A higher soil organic carbon stock was observed at the upper soil depth (0–10 cm). At lower soil depths, carbon stocks were smaller due to less plant residue and less biological activity in the deeper soil. In general, the study found that carbon density is high at lower altitudes and lower at higher altitudes. Therefore, altitude should be given due consideration for forest development and management for climate change mitigation. The result suggests that different governmental and nongovernmental organizations have to give due attention for forest conservation to reduce the CO2 emmission.

Assessment of water quality with comparative study of soil organic carbon stock in Nagdaha Lake and its adjacent agricultural land of Lalitpur, Nepal

Abstract. Bhatta M, Joshi R. 2023. Assessment of water quality with comparative study of soil organic carbon stock in Nagdaha Lake and its adjacent agricultural land of Lalitpur, Nepal. Intl J Bonorowo Wetlands 13: 9-16. The lakes are an important component of the terrestrial Carbon (C) cycle. Estimates of global C burial by lakes suggest burial rates ranging from 0.03-0.07 Pg C yr?1. In the present study, the water quality of Nagdaha Lake and comparative analysis of Soil Organic Carbon (SOC) in Nagdaha Lake and its adjoining agricultural area has been studied. Water quality was determined following APHA (1998); SOC was determined by the Walkey and Black (1934) Titration Method. The present study results show that the mean N-nitrate and P-phosphate concentration in the waters of Nagdaha Lake is 0.135 mg/L and 0.123 mg/L, respectively, and the mean SOC concentration of Nagdaha Lake (71.39±42.58g kg-1) is higher than the adjacent agricultural land (14.36±8.38g kg-1). The t-test result also shows that there is a significant difference in SOC concentration in lakes (t = 9.18) and agricultural (t = 7.66) for agricultural land (p < 0.0001). Nagdaha Lake's area decreased from 52 ropani to 42 ropani between 1964 and 2022. Despite the decrease in area, Nagdaha Lake has more carbon per unit area than agricultural land. Since the conversion of lake land to agricultural land can release a large amount of carbon into the atmosphere, it is imperative to preserve the lakes to mitigate increasing atmospheric CO2 concentration.

Comparative analysis of soil organic carbon in selected river catchments

The present study deals with the investigation of soil organic carbon in two water catchments in Northern Rila, Western Bulgaria. Field research, combined with analysis, provided sufficient data. Six key sites were selected and sampled in order to estimate and compare the amount of organic and inorganic carbon in the topsoil. The applied criteria for the choice of sites included: vegetation cover, predominant soil group, level of anthropogenization and transport accessibility. A total number of 13 samples from both catchments were collected and analyzed in the Central laboratory of the Institute of Soil Science, Agrotechnologies and Plant Protection (ISSAPP) “N. Pushkarov“. The results concern the amount and composition of soil organic matter in different soils – Cambisols (Albic, Humic, Dystric), Fluvisols and Umbrosols. The total carbon content of all samples varies between 1.23 and 9.69%. The amount of organic carbon ranges between 0.45 and 3.73%. The results of the study prove once again that the preservation of natural vegetation and current condition of the soil is of great importance for carbon sequestration and climate change mitigation.

Spectroscopic and Kinetic Study of Sucrose Oxidation by Cr(VI) and Its Application in the Quantitative Analysis of Soil Organic Carbon

The percent organic carbon (%OC) is an important soil fertility measure that has important implications in agricultural productivity and food security. In this study, a UV-visible spectrophotometric technique was investigated and applied to quantify %OC from selected soil samples along a river basin that traverses agricultural farmlands, a forest and sewage treatment lagoons for a comparative survey purposes. The study was based on the measurement of absorbance of Cr(III) species that arise from oxidation of sucrose (which is 42.11% carbon) by dichromate ions which contain Cr(VI) species. The uv-visible spectrophotometric double beam wavelength scan measurements elucidated the conversion of Cr(VI) to Cr(III) ions and a calibration plot was developed with r2= 0.99. The analyte peak was identified in the region from 750 nm to 550 nm (the absorbing Cr(iii) species) with a turning point maximum at 576 nm. The kinetic profile of sucrose oxidation by the dichromate ions was studied via absorbance of Cr(III) and Cr(VI) as a function of the reaction time and was used to characterize the reaction model. The absorbance of Cr(III) as a function of reaction time fitted best into the non-linear Belehradek power function equation y=a(x-b)c,, where y = absorbance; x = time(s); a, b, c = are constants (r2 of 0.91). Kinetic analysis revealed that the reaction that leads to the formation of Cr(III) during sucrose oxidation proceeds via pseudo first-order kinetics (r2= 0.83). A comparative quantitative analysis indicated that the sewage treatment lagoons had the highest %OC content at about 5.5-6.6%OC. The soils sampled from the forest regions had about 4.6-5.8%OC whereas the river bank soils had the lowest levels at about 2.0-2.5%OC. A statistical t-test analysis showed that the %OC levels in sub-soils were significantly higher than those of the top-soils (p > 0.05 at 95% CI).

LAND POTENTIAL FOR AGRICULTURE IN SUKOSARI VILLAGE, BANDONGAN DISTRICT, MAGELANG, CENTRAL JAVA

The purpose of this study is to characterize the physical, chemical, and biological properties of Sukosari land. The research was conducted via survey, evaluating the soil properties in agricultural areas to obtain 12 points at various altitudes. The results indicated that sand made up the most significant percentage of texture, ranging from 56 to 67 %. The analysis results of the soil's degree of acidity (pH) indicate that it is acidic, ranging between 4-5. The analysis of soil organic carbon, nitrogen, phosphorus, and potassium yielded low values. The total number of bacteria and fungi in the soil, on the other hand, is relatively high. As a result, it can be concluded that Sukosari's soil fertility is still relatively low. Additionally, it is recommended that the microorganisms present in each type of soil and land use Sukosari are identified.

Soil-moisture-index spectrum reconstruction improves partial least squares regression of spectral analysis of soil organic carbon

Soil-moisture-index spectrum reconstruction improves partial least squares regression of spectral analysis of soil organic carbon

Physical soil attributes in areas under forest/pasture conversion in northern Rondônia, Brazil.

The main cause of physical degradation in pasture areas is overgrazing, and when combined with poorly productive soils, it causes the loss of millions of hectares of agricultural soils a year. Thus, work is needed to indicate which physical attributes are most sensitive to degradation, generating information so that soil management can be proposed, with a view to economic, social, and environmental aspects. Therefore, the objective of the work was to evaluate the impacts caused on the physical attributes of the soil, in forests converted to pastures in northern Rondônia, Brazil. The study was carried out in three areas within the municipality of Porto Velho, Rondônia, one area with forest and two with pastures (brachiaria and mombaça grass). In the field, deformed soil samples were collected at a depth of 0.00-0.10 and 0.10-0.20m in the three study areas. In the laboratory, physical analyses of texture, aggregates and porosity, compaction, and an additional analysis of soil organic carbon were carried out. Then, univariate, bivariate, and multivariate analyses were performed, as well as geostatistical analysis. The conversion of forest to pasture had a negative impact on aggregates, compaction, porosity, and accumulation of organic carbon in the soil. The studied environments are influenced by the high levels of sand and clay, which interfere in the aggregation, compaction, porosity, and accumulation of organic carbon in the soil. We observed greater spatial variability of physical attributes in the environment with mombaça grass and attributed this to the greater grazing and trampling intensity of the animals.

Can Agricultural Management Induced Changes in Soil Organic Carbon Be Detected Using Mid-Infrared Spectroscopy?

A major limitation to building credible soil carbon sequestration programs is the cost of measuring soil carbon change. Diffuse reflectance spectroscopy (DRS) is considered a viable low-cost alternative to traditional laboratory analysis of soil organic carbon (SOC). While numerous studies have shown that DRS can produce accurate and precise estimates of SOC across landscapes, whether DRS can detect subtle management induced changes in SOC at a given site has not been resolved. Here, we leverage archived soil samples from seven long-term research trials in the U.S. to test this question using mid infrared (MIR) spectroscopy coupled with the USDA-NRCS Kellogg Soil Survey Laboratory MIR spectral library. Overall, MIR-based estimates of SOC%, with samples scanned on a secondary instrument, were excellent with the root mean square error ranging from 0.10 to 0.33% across the seven sites. In all but two instances, the same statistically significant (p < 0.10) management effect was found using both the lab-based SOC% and MIR estimated SOC% data. Despite some additional uncertainty, primarily in the form of bias, these results suggest that large existing MIR spectral libraries can be operationalized in other laboratories for successful carbon monitoring.

Vertical distribution analysis of soil organic carbon and total nitrogen in different land use patterns of an agro-organic farm

While the quantity of soil organic carbon and nitrogen are used as indices of soil quality assessment and sustainable land use management, soil microbial activity is also a sensitive indicator of soil quality. Though the dynamics of carbon and nitrogen in terrestrial ecosystem can be largely affected by macro factors such as climatic conditions, local micro environmental factors such as land use history, plant functional type and management practices also play an important role in this regard. The present study was aimed at assessing and analyzing different types of land use patterns so as to understand their influence on the depth wise distribution of soil organic carbon (SOC), total nitrogen (TN) and microbial activity under the same management practices. The investigation was carried out in an organic farm located at Anand, Gujarat, India. Three different types of land use patterns viz., (i) fodder grass raising land, (ii) teak woodland, and (iii) wheat-pearl millet cropland were selected. Vertical (0–100 cm depth) variation in soil biophysical properties was recorded. Analysis of variance showed SOC (%) and TN (%) varied significantly (P < 0.001) with land use patterns (LU), depth (D), and LUxD. It was found that at all three land use patterns SOC and TN were highest at upper layer (0–10 cm) then decreased towards deeper layers (up to 40 cm) and then again increased with depth (40–100 cm) in soil profile. Highest values of SOC (%) and TN (%) (1.02% and 0.08% respectively), were reported in wheat-pearl millet cropland at 0–10 cm depth. Use of organic amendment made a great impact on SOC (%) in wheat pearl-millet cropland throughout the soil profile. We found almost same quantity of SOC (%) at 0–10 cm and 80–100 cm in teak woodland and grass raising land. The microbial biomass (carbon and nitrogen) and dehydrogenase activity were also found to be highest at upper layer (0–10 cm) in wheat-pearl millet cropland (418.2 µg/g, 52.9 µg/g and 104.05 TPF µg/g respectively) as compared to other two types of land use patterns. A significant positive correlation was observed between soil organic carbon and total nitrogen with microbial biomass and dehydrogenase activity at all three land use patterns. Our findings suggest that changes in land use pattern and management practices make a significant impact on vertical distribution of SOC and TN. Accurate investigation of SOC and TN storage at regional levels is important for detecting changes in carbon and nitrogen sequestration potentials induced by land use changes over a period of time to enable the rebuilding of SOC and TN in agro-ecosystems.

Regenerative rotational grazing management of dairy sheep increases springtime grass production and topsoil carbon storage

Increased traditional dairy sheep production in the Basque Country of northern Spain could substantially affect pasture soils. This type of agricultural land performs vital functions and provides essential ecosystem services. Regenerative farming practices such as rotational grazing with prolonged resting periods are designed to improve farmland soil health, while profitably delivering high-quality farm products. The aim of this study was to determine the mid-term effect of rotational grazing on soil ecosystem services and evaluate their synergies and trade-offs. A 4.5-ha experimental pasture was divided into two sections: one subjected to regenerative rotational grazing and the other to conventional rotational grazing. A flock of 135 Latxa breed dairy ewes was evenly distributed over the two areas during six consecutive years. On the conventional rotational grazing section, the sheep were allowed to feed for 6–10 d followed by a 15-d rest period. On the regenerative rotational grazing section, the sheep were allowed to feed for 1–2 d followed by a 24-d rest period. Vegetation and soil were then sampled according to a grid design. Springtime grass production was estimated by cutting the vegetation, topsoil carbon storage was determined through elemental analysis of soil organic carbon, nutrient cycling was calculated by measuring the activity of six enzymes (β-glucosidase, β-glucosaminidase, sulfatase, acid phosphatase, L-alanine aminopeptidase, and L-leucine aminopeptidase), water flow regulation was calculated using a simplified water retention index, and biodiversity was determined via 16S rRNA metabarcoding of soil prokaryotes. Regenerative rotational grazing achieved 30% higher springtime grass production and 3.6% higher topsoil carbon storage than conventional rotational grazing. The other parameters did not differ significantly between the grazing regimes. Regenerative rotational grazing reduced relative data dispersion for all ecosystem services, possibly because it supported comparatively homogeneous pasture use by livestock and avoided the negative consequences of overgrazing and undergrazing. Thus, regenerative rotational grazing might effectively improve certain soil ecosystem services without causing trade-offs to others.

Comparison, limitations and uncertainty of wet chemistry techniques, loss on ignition and dry combustion in soil organic carbon analysis

Comparison, limitations and uncertainty of wet chemistry techniques, loss on ignition and dry combustion in soil organic carbon analysis

Improved method for removing siderite by in situ acidification before elemental and isotope analysis of soil organic carbon

AbstractSiderite (FeCO3) is an iron carbonate mineral commonly found in sediments and soils. Similarly to other carbonates, such as calcite or dolomite, it may substantially affect the quantification of organic carbon (C) as well as determination of C isotope ratio of soil organic matter. Both analyses require effective removal of siderite by pretreatment with acid. However, little is known about the siderite removal efficiency of the acid pretreatment methods which have been previously proposed in the literature.In our study, we tested three previously proposed carbonate removal methods for siderite removal in siderite‐containing soils. Furthermore, we tested whether siderite C content in a soil sample can be detected as CO2 evolved after H3PO4 addition which would allow organic C determination from the difference between total and inorganic C.None of the three tested pretreatment methods led to sufficient removal of siderite C when applied on siderite alone. Therefore, we developed a new protocol for a 4‐day treatment with 10% HCl at 25°C. At siderite content of up to 10 wt.%, the removal efficiency of our method (99–100%) was sufficient both for organic C as well as for C isotope analyses. This was further confirmed with tests on siderite‐containing soils. These showed that the method of Larson et al. () developed for sediments is also suitable. However, the new protocol provides advantage in terms of less microplate manipulation, capsule overflow and oven use. We found that CO2 is not evolved 2 minutes after H3PO4 addition from siderite in contrast to calcite and dolomite. This fact can be used for separate quantification of inorganic C from calcite/dolomite and siderite, e.g., in studies of their different role in soil development. We showed that siderite‐containing soils require special pretreatment procedure before organic C and 13C/12C analyses. We recommend using our protocol if techniques such as XRD or SEM‐EDS indicate the presence of siderite in soil.

Climate change, agricultural inputs, cropping diversity, and environment affect soil carbon and respiration: A case study in Saskatchewan, Canada

Climate change, agricultural inputs, cropping diversity, and environment have seldom been combined in analyses of soil organic carbon (SOC), and soil C respired through microbial respiration (MR). This modeling study assessed SOC and MR simulated with the Environmental Policy Integrated Climate (EPIC) model for historical weather (1971–2000) and future climate scenarios (2041–2070) for the Alternative Cropping Systems (ACS) study research site in Saskatchewan, Canada. Nineteen years of field and crop management information from the 1994–2013 ACS study were used to validate and provide parameters to the EPIC model for analyses of climate change scenarios. The ACS study consisted of three levels of agricultural inputs [organic (ORG), reduced (RED), and high (HI)] and three levels of cropping diversity [low (LOW), diversified annual grains (DAG), and diversified annuals and perennials (DAP)]. Changes in future SOC and MR under climate change were explored with ANOVA and recursive partitioning in multivariate analyses of inputs, diversity, growing season precipitation (GSP), growing degree days (GDD), annual average maximum, minimum temperatures, cumulative annual precipitation, and terrain attributes (TA). Under climate change, SOC decreased by 1.3% (from 132.3 to 130.6 Mg ha−1) of original stocks in the 0–90 cm. Microbial respiration was affected by climate change and increased by 17% (from 1.92 to 2.25 Mg C ha−1 y−1) due to an increase in annual maximum and minimum temperatures. The increase in annual maximum and minimum temperature was correlated with 32 and 42% of variation in SOC respectively. Monthly growing season GDD was correlated with 14% of variation of SOC in an analysis independent of annual data. Annual precipitation did not affect SOC, though May GSP accounted for 16% of total variation in SOC, while June temperature accounted for 9% of variation in MR. The combination of input and diversity was correlated with 3 and 7% of variation in SOC and MR, respectively. The combination of RED inputs and DAG diversity are the best option to manage SOC and reduce the amount of soil C respired under climate change relative to organic and conventional systems.

Biochar Effects on Carbon Stocks in the Coffee Agroforestry Systems of the Himalayas

Coffee agroforestry is an emerging agricultural practice in the mid hills of Nepal. Smallholder farmers of low-income strata have progressively adopted coffee as a perennial crop over seasonal crops. A multi-year study was conducted to test effects of locally produced biochar derived from coffee wastes, e.g., pulp and husks, on carbon stocks of: i) coffee trees, and, ii) soil organic carbon (SOC) in selected coffee growing pockets. We conducted on-farm experimental trials in three different physiographical locations of the Nepal mid-hills, namely, Chandanpur (Site I at 1475masl), Panchkhal (Site II at 1075masl), and Talamarang (Site III at 821masl) where smallholders grow coffee together with other cereal crops and vegetables. We applied biochar to the soil at a rate of 5 Mgha-1, then, monitored the SOC and biomass growth of the coffee trees in the three treatment plots at sites I, II and III over two years beginning in 2013. The average stocks of aboveground carbon in coffee trees increased from 6.2&amp;plusmn;4.3 Mgha-1 to 9.1&amp;plusmn;5.2 Mgha-1 over the trial period of two years in biochar treated plots. The same in control plots increased from 5.6&amp;plusmn;2.8 Mgha-1 to 6.7&amp;plusmn;4.7 Mgha-1. In the biochar plots, the average increments of ABG carbon was 0.73 Mgh-1 while in the control it was 0.29 Mgh-1. Analysis of soil organic carbon of the plots indicated overall incremental change in carbon stocks in the coffee farms. During the base year, the average SOC stocks in the top 0-15cm layer of the soil at sites I, II, and III were estimated 74.88 &amp;plusmn; 15.93; 63.96 &amp;plusmn;16.71 and 33.05 &amp;plusmn;4.42 Mgha-1 respectively. Although both the biochar treated and control plot registered incremental change in SOC stocks, the volumes were remarkably higher in the former than the latter. Compared to the baseline data, the changes in SOC stocks in the three biochar treated plots were 19.8, 49.8 and 45.3 Mgha-1, respectively, whereas in the control plots these were 8.3, 29.3 and 11.3 Mgha-1, respectively. The higher incremental rates of C-stocks in all the biochar treated plots in comparison to the corresponding control plots of the coffee agroforestry implies that application of biochar can enhance accumulation of carbon in the form of aboveground biomass and soil organic carbon.

Curve-fitting techniques improve the mid-infrared analysis of soil organic carbon: a case study for Brookston clay loam particle-size fractions

Few studies have evaluated structural features of soil organic carbon (SOC) in different soil particle fractions, especially SOC changes induced by tillage, using Fourier transformed mid-infrared (MIR) spectroscopy. To make a contribution in this context, soil samples of a Brookston clay loam (mesic Typic Argiaquoll) with averaged pH and organic matter concentration at 7.28 and 43.9 g kg−1, respectively, were collected from short-term no-tillage (NT97) and mouldboard plow (CT97) treatments initiated in 1997 and long-term no-tillage (NT83) and mouldboard plow (CT83) treatments initiated in 1983 under a corn-soybean rotation, and were separated into sand, silt, and clay fractions using sonication. Structural features of SOC in these soil fractions were investigated using curve-fitting analysis of mid-infrared (MIR) spectra. Aromatic C content was found to be greater in clay- than in sand-sized fractions, while aliphatic C content was higher in sand- than in silt- and clay-sized particles. With decrease in tillage intensity, the aliphatic C gradually increased in sand- and clay-sized fractions but not in the silt-sized fraction. The aliphatic C content in sand fraction was significantly greater in NT83 than CT83 (P < 0.05). The aromatic C in silt- and clay-sized fractions was greater in NT83 than in both CT soils, whereas aromatic C contents were higher in both CT soils than in NT83 soil. Significantly higher aromatic/aliphatic C ratio in CT83 than NT83 was found in sand-sized fractions, while the opposite trend was found in the silt-sized fraction. These findings were not apparent until the curve-fitting technique was employed, which has the capacity to quantify many overlapped bands in the spectra. This study demonstrates that the curve-fitting of MIR spectra advances the analysis of organic matter in soil samples.

Soil ploughing for forest regeneration leads to changes in carbon decomposition – a case study with stable isotopes

Abstract It is important to quantify carbon decomposition to assess the reforestation impact on the forest floor C stocks. Estimating the loss of C stock in a short-term perspective requires measuring changes in soil respiration. This is not trivial due to the contribution of both soil microbes and vegetation to the measured CO2 flux. However, C stable isotopes can be used to partition the respiration and potentially to assess how much of the recalcitrant C stock in the forest floor is lost. Here, we measured the soil respiration at two forest sites where different regeneration methods were applied, along with an intact forest soil for reference. In so doing, we used a closed dynamic chamber for measuring respiration and the 13C composition of the emitted CO2. The chamber measurements were then supplemented with the soil organic carbon analysis and its δ13C content. The mean δ13C-CO2 estimates for the source of the CO2 were -26.4, -27.9 and -29.5‰, for the forest, unploughed and ploughed, respectively. The 13C of the soil organic carbon did, not differ significantly between sites. The higher soil respiration rate at the forest, as compared to the unploughed site, could be attributed to the autotrophic respiration by the forest floor vegetation.

Geospatial Distribution of Soil Organic Carbon in the Bhima River Watershed Region of Solapur District, Maharashtra, India

Objectives: To determine the Soil Organic Carbon Density (SOCD) and to observe distribution of Soil Organic Carbon (SOC) in the Bhima River sub-watershed of Solapur. Methods/Analysis: The spatial distribution of Soil Organic Carbon and it density was shown by Inverse Distance Weighted (IDW) interpolation technique using ArcGIS and the subsequent map generated in the process account for the fertility across the watershed and its longitudinal section. Total 36 sampling points were used for soil sampling and are processed for the output map. The land cover type of barren land and agriculture field were selected for soil sampling. Walkley and Black method was used for analysis of soil organic carbon and organic matter was calculated as a derived parameter. Findings: It is found that average soil bulk density was 1.15 gm cm-3 and the difference in SOCD from the minimum to maximum was 2.85 kg/m2 with average of 1.87 kg/m2. The lower values carbon was at high elevation and higher values were recorded nearer to mouth of river. There seems to be insignificant correlation between bulk density and SOC. Applications/Improvements: The SOC comparison between different land cover, clearly shows that agricultural terrains were richer as compared to barren lands. The outcome of the research could be of importance for the policy makers and management of agriculture, as SOC is the major nutrient in terrestrial ecosystems.

A State‐Space Analysis of Soil Organic Carbon in China's Loess Plateau

AbstractAn accurate estimation of soil organic carbon (SOC) is important for the evaluation and management of carbon (C) flux in terrestrial ecosystems. However, there is little work on the spatial variability of SOC in deep soils and its driving factors. Thus, the objective of the study was to derive the primary factors dominating the spatial distribution of SOC in different soil layers with the use of the autoregressive state‐space approach. The concentration of SOC was measured to the depth of 500 cm (n = 86) along a south–north transect of China's Loess Plateau. The mean SOC of the 500‐cm soil profile generally decreased from south to north following the decreasing rainfall gradient. Based on the investigated factors, the state‐space model was able to capture 90.3–99.9% of the spatial variability of SOC in the various soil layers. According to the coefficients in the optimal state‐space model for each soil layer, climatic factors such as precipitation and temperature had a dominant control over the spatial distribution of SOC at shallow depths. However, both climatic and edaphic (e.g. soil texture) factors, and to a small extent land use, influenced the spatial behavior of SOC at the 40–200 cm soil depth. For soil layers below 200 cm, the importance of land use was revealed, and the spatial characteristics of SOC were together driven by land use, climatic and edaphic factors. This is critical for the management of soil C flux in deep soils and the C stock and cycle in terrestrial ecosystems.Table SI. Basic properties of soils and climate and elevation under three land uses along the south–north transect on the Loess Plateau (mean ± standard deviation). Note that SWC is gravimetric soil water content. Copyright © 2016 John Wiley &amp; Sons, Ltd.