Impact of plastic film mulching and fertilizers on the distribution of straw-derived nitrogen in a soil-plant system based on 15N–labeling

Abstract Crop yield response to nitrogen (N) application has been well documented, but quantitatively tracing the distribution of exogenous straw derived N (straw-N) in a soil-plant system amended by plastic film mulching and fertilizers is poorly understood. Focus on this, we used a 15 N tracer, applied as maize straw, into a monoculture maize field experiment in China to quantify the distribution of straw-N in a soil-maize system. The effects of straw-N utilization by maize were also assessed over the course of a six-month field experiment by adding 15 N labeled maize straw into four fertilizer treatments (no fertilizer, N chemical fertilizer alone, manure fertilizer alone and manure combined with N chemical fertilizer) both with and without mulching. Mulching promoted straw-N transfer to stems, leaves and grains of maize. Fertilizers increased straw-N transfer to these plant parts both with and without mulching due to the increase of plant biomass, showing greater plant utilization rates of straw-N in the N fertilizer addition treatments, while residual rates of straw-N in soil decreased in these treatments. Nevertheless, fertilizer application relatively decreased the contribution of straw-N to N uptake of plant. The manure combined with N fertilizer treatment both with and without mulching had resulted in the highest straw-N accumulation in plant, but the lowest straw-N accumulation in soil. Meanwhile, mulching significantly increased straw-N distribution in plant but decreased in soil in the manure and manure combined N treatments. These results suggested that there were differences in straw-N turnover and uptake by maize in the soil-maize system due to the influences of plastic film mulching and different N sources of inorganic and organic fertilizers, especially showing that inorganic fertilizer positively primed straw-N distribution to plant compared to organic fertilizer.