Soil aggregate and organic carbon distribution at dry land soil and paddy soil: the role of different straws returning

Abstract

Agriculture wastes returning to soil is one of common ways to reuse crop straws in China. The returned straws are expected to improve the fertility and structural stability of soil during the degradation of straw it selves. The in situ effect of different straw (wheat, rice, maize, rape, and broad bean) applications for soil aggregate stability and soil organic carbon (SOC) distribution were studied at both dry land soil and paddy soil in this study. Wet sieving procedures were used to separate soil aggregate sizes. Aggregate stability indicators including mean weight diameter, geometric mean diameter, mean weight of specific surface area, and the fractal dimension were used to evaluate soil aggregate stability after the incubation of straws returning. Meanwhile, the variation and distribution of SOC in different-sized aggregates were further studied. Results showed that the application of straws, especially rape straw at dry land soil and rice straw at paddy soil, increased the fractions of macro-aggregate (> 0.25 mm) and micro-aggregate (0.25-0.053 mm). Suggesting the nutrients released from straw degradation promotes the growing of soil aggregates directly and indirectly. The application of different straws increased the SOC content at both soils and the SOC mainly distributed at < 0.53 mm aggregates. However, the contribution of SOC in macro- and micro-aggregates increased. Straw-applied paddy soil have a higher total SOC content but lower SOC contents at > 0.25 and 0.25-0.053 mm aggregates with dry land soil. Rape straw in dry land and rice straw in paddy field could stabilize soil aggregates and increasing SOC contents best.

Effect of straw amendment modes on soil organic carbon, nitrogen sequestration and crop yield on the North‐Central Plain of China

“…We observed that high amounts of straw addition decreased the mass proportion of the silt plus clay fraction and increased the mass proportion of large macroaggregates but had no effect on the mass proportions of small macroaggregates and microaggregates (Table ). This result is consistent with Huang, Lan, Liu, and Gao (), Long et al. () and Garcia‐Franco, Albaladejo, Almagro, and Martínez‐Mena () who found that straw amendments increased the fractions of large and small macroaggregates (>0.25 mm) and microaggregates (0.25–0.053 mm) and reduced the proportion of microaggregates and the silt plus clay fraction.…”

Aggregate Stability under Long-Term Fertilization Practices: The Case of Eroded Ultisols of South-Central China

“…Correspondingly, the incorporation of straw could lead to soil particles to stick together, which in turn, form soil aggregates. Similar results have been reported [14,[53][54][55].…”

Effects of Biochar on the Net Greenhouse Gas Emissions under Continuous Flooding and Water-Saving Irrigation Conditions in Paddy Soils

“…The available phosphorus (AP) content was extracted by a 0.5 mol L −1 NaHCO 3 (pH 8.5) solution. The available potassium (AK) content was extracted by using 1 mol L −1 NH 4 Ac (pH 7.0) [39]. The soil organic carbon (SOC) was determined by K 2 Cr 2 O 7 oxidation and FeSO 4 titration [40].…”