Long-term non-flooded mulching cultivation influences rice productivity and soil organic carbon

A field experiment was conducted for 10 years to examine the long-term effects of non-flooded mulching cultivation on rice yield and soil organic carbon on Chengdu Plain, south-west China. Compared with traditional flooded cultivation (TF), non-flooded plastic film mulching (PM) resulted in a 14% higher average rice (Oryza sativa L.) yield. However, non-flooded straw mulching (SM) decreased the average rice yield by 11% compared with TF. After 10 years, PM led to similar or higher (SM) soil organic carbon (SOC) and total soil N (TN) in the top 5 cm of the soil profile compared with TF. No differences were found among the three cultivation systems in SOC or total N at 512 and 1224 cm soil depths. Small macroaggregates (0.252 mm) were predominant in the top 5 cm of the soil (5863% of whole soil) across the three cultivation systems. However, the proportion of large macroaggregates (>2 mm) from SM and PM was significantly larger than from TF in the top 5 cm of the soil. Non-flooded mulching cultivation led to increased C and N contents in large macroaggregates and mean weight diameter of aggregates in the 05 cm soil depth. This suggests that non-flooded mulching cultivation increased soil aggregation concomitant with soil C stabilization within the improved soil structure.