Non‐flooding rice yield response to straw biochar and controlled‐release fertilizer

The non‐flooding plastic film‐mulching cultivation (NFMC) is an important water‐saving rice (Oryza sativa L.) production technique for mountainous areas. Several studies indicated that this promising production system had positive effects on rice growth compared with the traditional flooding method. However, two obvious disadvantages need to be modified for its wider application: technical difficulties for mid‐season application of fertilizer and the observed loss of soil C. The solution for these problems may lead to enhanced and more sustainable rice production under NFMC conditions. A 2‐yr field experiment was conducted to evaluate the effects of combining straw biochar and controlled‐release urea with the NFMC system. The experimental design included two treatments of traditional flooded cultivation: (a) no N fertilizer; (b) urea alone; and four treatments under NFMC conditions: (a) no N fertilizer; (b) urea alone; (c) controlled‐release urea + urea; (d) a combination of straw biochar and controlled‐release urea + urea. Compared to a basal application of urea, controlled‐release urea plus urea together with straw biochar significantly increased rice grain yield and effective panicles. It also increased total biomass accumulation, the greenness of the leaves (SPAD value) and improved recovery efficiency of applied N. Our results show that the combination of controlled‐release urea and straw biochar can increase yield and N use efficiency of rice under NFMC conditions.