Returning Winter Cover Crop Residue Influences Soil Aggregation and Humic Substances under Double-cropped Rice Fields

ABSTRACT Residue management in cropping systems may improve soil quality. However, there are few studies on the effects of residue management on soil aggregation and carbon content in the humin (C-HUM), humic acid (C-HAF) and fulvic acid (C-FAF) fractions in South China. Therefore, the effects on soil aggregation and on the C-HUM, C-HAF, C-FAF from incorporating winter cover crop residues in a double-cropped rice (Oryza sativa L.) system in South China fields were studied. The experiment has been conducted since winter 2004. Five winter cropping systems were used: rice-rice-ryegrass (Ry-R-R), ...