Soil Organic Carbon and Labile Carbon Pools Attributed by Tillage, Crop Residue and Crop Rotation Management in Sweet Sorghum Cropping System

Abstract

Labile organic carbon (LOC) fractions are considered as sensitive indicators of change in soil quality and can serve as proxies for soil organic carbon (SOC). Although the impact of tillage, crop rotation and crop residue management on soil quality is well known, less is known about LOC and SOC dynamics in the sweet sorghum production systems in South Africa. This short-term study tested two tillage levels: no-till and conventional-tillage, two crop rotations: sweet-sorghum/winter grazing vetch/sweet sorghum and sweet-sorghum/winter fallow/sweet sorghum rotations and three crop residue retention levels: 30%, 15% and 0%. Tillage was the main factor to influence SOC and LOC fractions under the sweet sorghum cropping system in South Africa. NT increased SOC and all LOC fractions compared to CT, which concurs with previous findings. Cold water extractable organic carbon (CWEOC) and hot water extractable organic carbon (HWEOC) were found to be more sensitive to tillage and strongly positively correlated to SOC. An increase in residue retention led to an increase in microbial biomass carbon (MBC). This study concludes that CWEOC and HWEOC can serve as sensitive early indicators of change in soil quality and are an ideal proxy for SOC in the sweet-sorghum cropping system in South Africa.

Effect of soil management systems on the rhizosphere bacterial community structure of tobacco: Continuous cropping vs. paddy-upland rotation

“…Specifically, tobacco continuous cropping presented better effects on improving the soil environment than the tobacco-rice rotation cropping system. This observation was contradictory to other studies which indicated that the rotation cropping system was beneficial in enhancing soil fertility (Malobane et al, 2020;Zhang et al, 2022). This result can be ascribed to the amount of debris remaining in the field after each crop in a continuous cropping system, even after removing the tobacco stalks (Triberti et al, 2016).…”

Comparison of Some Soil Enzymatic Activities in Luvisol of Conservation and Conventional Tillage in a Model Experiment

“…1). This circumstance indicated that high organic matter input by the crop residue increase the soil carbon content and it confirmed the previous results by BONGIORNO et al (2019); MALOBANE et al (2020); KOTROCZÓ et al (2022).Our finding also suggested that the more intensive tillage practice, the lower soil organic carbon concentration. It could be explained that conventional tillage practice damages the soil structure.…”

Long‐term conservation and conventional tillage systems impact physical and biochemical soil health indicators in a corn–soybean rotation

“…The HWC consists of more readily available substances (labile fraction) such as carbohydrates, phenols, and lignin monomers (Landgraf et al., 2006). Cold‐water extractable C and HWC can be more sensitive to tillage and positively correlated to SOC (Malobane et al., 2020). Hot‐water extractable N is a useful predictor for tillage practices, N mineralization, and available N, providing recommendations on the optimum N dose that should be applied (Zhou et al., 2012).…”