Using Controlled Release Fertilizers to Rice Growth, Yield and Nitrogen Use Efficiency.

Abstract China accounts for nearly 30% of global rice production which consume 7% of global nitrogen (N) fertilizer. Because the utilization rate of N in rice is about 30% ~35% in China, most of N from fertilizer entered into surface water or ground water. The objective of this study was to evaluate the possibility to improve N use of rice in China by applying controlled release nitrogen fertilizer (CRNF). Field experiments were conducted at Banqiao and Wangzhuan, Jiangsu, China. Plant growth, N uptake, rice grain yield and ammonia loss were investigated. At Banqiao site, applied CRNF had significantly higher plant N content than applied urea at the same N level. There was no significant difference in plant N content between CRNF and Urea at the same N level at Wangzhuan site. There were no significant difference in agronomy nitrogen use efficiency (NAE) and nitrogen recovery efficiency (NRE) between CRNF and Urea at equal N applied in the two sites. N harvest index (NHI) in CRNF was lower than urea from the two tests. Ammonia loss at CRNF was 7.3 kg/ha which was significantly lower than 21.2 kg N from urea at 200 kg N applied at Wangzhuan. At low N applied, CRNF had significant higher grain yield than urea at Banqiao. This study indicated effect of CRNF on rice growth varied with experimental sites. Beside CRNF having the advantage in labor-saving for fertilization and reducing nitrogen loss, key issues about how to efficiently apply CRNF in growing rice from formulation of CRNF, soil fertility and plant N need are further discussed.