Responses of rice production, milled rice quality and soil properties to various nitrogen inputs and rice straw incorporation under continuous plastic film mulching cultivation

Yield decline from continuous cropping of aerobic rice is a constraint to the widespread adoption of plastic film mulching cultivation (PFMC); rice straw incorporation has been proposed to counter this negative effect of long term PFMC. Shifts in water management from flooded to aerobic conditions are known to influence the availability of N and might have an influence on rice quality. A long-term (2001-2010) field experiment was conducted to examine the effects of five fertilizer nitrogen (N) application rates (0, 45, 90, 135, 180 kg N ha−1) and rice straw incorporation on rice grain yield, milled rice quality and soil quality under PFMC in non-flooded conditions. There were significant responses in grain yield to various N fertilizer rates and rice straw incorporation during 2008 to 2010. Total amino acids and protein concentrations in polished rice increased with increasing N rates. Split-plot factor significantly affected soil fertility and rice plant N uptake in our study. With rice straw incorporation, total annual and mean amount of soil organic matter was improved by 6.4%, 7.6% and 12.2%; NH4OAC-extractable K amount was improved by 28.2%, 64.0% and 52.9%; N uptake was improved by 20.4%, 23.9% and 23.6%, respectively, from the year of 2008 to 2010. Dynamics of rice grain yield, soil organic matter, alkali-hydrolyzable N and NH4OAC-extractable K from 2001 to 2010 proved that rice straw incorporation obviously improved rice grain yield and soil quality under continuous PFMC. Our results suggest that there is a possibility of reversing yield decline observed in the continuous PFMC system by using rice straw incorporation.