Comparing Estimation Methods for Soil Organic Carbon Storage in Small Karst Watersheds

Abstract

In order to accurately estimate soil organic carbon storage (SOCS), 2,755 soil profiles and 23,536 soil samples were acquired by grid method, followed by a study on the SOCS, soil bulk density (SBD), gravel content (GC), and distribution characteristics of rock coverage (RC) in a small karst watershed (SKC). Then on the basis of soil profile summation, an investigation was done on the applicability of RC/GC-based soil type method, land utilization type method, and aspect method to the estimation of SOCS in SKC at different depths. As shown by the results, the average soil organic carbon content (SOC) in the soil samples ranged from 5.25 to 24.87 g.kg-1 , and decreased with the soil depth increasing; the average SBD ranged from 1.17 to 1.41 g.cm-3 , which first increased with the soil depth increasing and then tended to be steady; the average GC ranged from 0 to 20.15%, which decreased gradually with the soil depth increasing and finally to zero; the RC ranged from 0 to 86.32% at different sample points. RC and GC greatly affected the estimation of SOCS, so after correction based on RC and GC, the soil type method was adopted for estimation, concluding that SOCS at depths of 0-20 cm, 0-30 cm, and 0-100 cm was 341.82×10 6 kg, 449.29×10 6 kg, and 738.351×0 6 kg, respectively; RC and GC affected white sandy soil the most, as shown by the following SOCS estimated by the land utilization type method: 319.56×10 6 kg, 416.04×10 6 kg, and 607.02×10 6 kg, respectively, at depths of 0-20 cm, 0-30 cm, and 0-100 cm; RC and GC affected wasteland the most, as shown by the following SOCS estimated by the aspect method: 318.64×10 6 kg, 411.63×10 6 kg, and 628.46×10 6 kg, respectively, at depths of 0-20 cm, 0-30 cm, and 0-100 cm; RC and GC affected the SOCS in the south slope the most; in terms of catchment scale, the "vertical stratification + horizontal classification" pattern was expanded to the "land utilization type method" and "aspect method." For estimating the SOCS in topsoil, the aspect method achieved the best result, while the land utilization type method achieved the best result at a depth of 100 cm.

Response of Soil Organic Carbon and Its Active Fractions to Restoration Measures in the Karst Rocky Desertification Ecosystem, SW China

“…The LOC/SOC is more reflective of the effect of vegetation on soil behavior than LOC [11,50]. This study showed that the soil WSOC/SOC of the six control measures ranged from 0.31% to 0.74%.…”

“…The soil carbon pool is about twice that of atmospheric and three times that of vegetation carbon pool, in which the soil organic carbon (SOC) contents accounts for more than 50% of the total soil carbon [2][3][4], and small changes in SOC storage will have a significant impact on atmospheric CO 2 concentrations [5][6][7][8]. However, SOC content is only a result of longterm balanced mineralization of soil organic carbon, and it is difficult to respond to short-term land use changes, and it cannot well reflect the changes of soil quality and conversion rates in a short time [9][10][11][12]. Previous studies have found that soil labile organic carbon (LOC) was more sensitive to land use change than SOC [13][14][15][16][17][18][19].…”

Distribution of Heavy Metal Contents in Soil Producing <i>Uncaria rhynchophylla</i> (Miq.) Miq. ex Havil. In Guizhou: Driven by Land Use Patterns

“…Any two of the Cu, Pb, Hg and Cr exhibit an extremely significant positive correlation or positive correlation, indicating that they share a similar pollutant source. The URM producing areas is a typical karst area, and there are a large number of soluble carbonate bedrocks in the territory, and the weathering of carbonate bedrock has a strong enrichment effect on the elements in the product [28,29], leading to a strong positive correlation between part of the heavy metals (Cu, Pb, Hg and Cr). In addition to natural factors, human factors also have a great influence on soil [30], long-term application of fertilizers that contain a certain amount of heavy metal pollutants like Cu, Pb, Hg and Cr also leads to a relatively strong positive correlation between these elements.…”

Effects of Land Use Change of Sloping Farmland on Characteristic of Soil Erosion Resistance in Typical Karst Mountainous Areas of Southwestern China

“…Soil mechanics mechanism is an important research content of soil erosion and soil and water conservation, and researchers mainly elucidate the vegetation regulating role through shear strength of the soil-root composite system [29][30][31]. Compared with the regulation mechanism of ground vegetation on soil and water loss, the study of underground root systems on soil and water conservation is much less, which is mainly caused by the study of an underground root system being relatively difficult [32].…”