Quantification of yield gap and nutrient use efficiency of irrigated rice in China

Analyzing attainable yield (YA), yield gap (YG), and nutrient use efficiency (NUE) will help develop and inform agricultural policies and strategies to increase grain yield. Data from a total of 2218 on-farm rice experiments were collected between 2000 and 2013 from the main rice production areas of China. Common treatments in each study included the optimum nutrient management (OPT), farmers’ fertilizer practices (FP) and nutrient omission treatments which were used to assess YG, yield response to nutrient (YR), and NUE. This study used meta-analysis and ANOVA to evaluate differences across the four rice planting seasons (early, middle, late, and single-season rice). The average YA from the OPT was 8.5 t/ha, and the yield gap between OPT and FP was 0.6 t/ha. The YR to nitrogen (N), phosphorus (P),and potassium (K) averaged 2.4, 0.9, and 1.0 t/ha across all sites, respectively. Results using the Pearson’ correlation analysis showed significantly negative coefficients for YR to soil nutrient contents and soil organic matter. The large variations in YR were attributed to differences in climatic conditions and soil indigenous nutrient supplies. As compared to FP, the average recovery efficiency (RE) to N, P, and K with OPT increased by 10.1, 5.0 and 8.6 percent across all sites, respectively. In order to narrow the YG and increase NUE, effective soil, plant, nutrient management measures, advances in knowledge and technologies would be required to sustain higher crop production.