Abstract:
To clarify the influences of green manure and rice straw returning on the composition and organic matter percentage of aggregates in tobacco-planting soils, field experiments were carried out in typical tobacco-planting areas of Hunan from 2015 to 2017. The results showed that comparing with the soils applied chemical fertilizer only (CK), the organic matter contents in soils applied with rice straw, rapes, arrow peas and ryegrass increased by 2.80%, 3.24%, 0.84% and 0.48%, respectively. Green manure and rice straw returning improved soil aggregate characteristics, increased the content, mean weight diameter (MWD) and geometric mean diameter (GMD) of large aggregates, and reduced their fractal dimension (D). Viewing from soil aggregate characteristics, the effects of rape returning and ryegrass returning were superior to rice straw returning and arrow pea returning, respectively. In addition, green manure and rice straw returning influenced the organic matter percentage in aggregates of different sizes, and organic matter presented a transfer trend from small aggregates to large aggregates. Their influences on the organic matter percentage in aggregates larger than 2.000 mm were greater, and the percentage increased by 24.51%, 30.00%, 14.29%, and 39.48% after rice straw, rapes, arrow peas and ryegrass returning, respectively. Therefore, green manure and rice straw returning could effectively improve tobacco-planting soils.