Nitrogen leakage in a rice-duck co-culture system with different fertilizer treatments in China.

Nitrogen (N) leakage in paddy fields can cause groundwater pollution. In this study, we conducted a split-plot field experiment over 2 years to compare N leakage in a rice-duck co-culture system and a rice monoculture system with different fertilizer treatments. Four treatments were applied to each field, with consistent N inputs in each fertilizer treatment: no fertilizer (RD and RM, respectively), chemical fertilizer (RDF and RMF, respectively), organic fertilizer (RDO and RMO, respectively), and a mixture of 70% chemical and 30% organic fertilizers (RDFO and RMFO, respectively). In both years, rice-duck co-culture system had lower N leakage than the rice monoculture for the same fertilizer treatment, with average reductions of 14.3 ±â€¯0.1%, 13.5 ±â€¯4.5% and 10.5 ±â€¯3.3% for RDFO, RDF and RDO, respectively. Within the rice-duck co-culture system, the average N leakage across both years was 36.3 ±â€¯6.3% lower in RDO and 16.9 ±â€¯11.5% lower in RDFO than in RMF. RDFO gave the highest grain yield compared with RDF and RDO, average reached 10.35 t ha-1 across both years. In conclusion, our results suggested that rice-duck co-culture reduces environmental risks by controlling N leakage and increasing agricultural productivity. Compared with other treatments in this research, RDFO was the most recommended agricultural production mode in this region because it can reduce the inputs of chemical fertilizer, control nitrogen leakage and increase rice yield.