Abstract:

Short-term and long-term experiments were conducted to determine the effects of phosphorus (P) fertilizer reduction on rice yield and phosphorus utilization. In the short-term experiment, three treatments, including normal P application (P1), half-dosage P application as basal dressing (P2), half-dosage P application with 50% as basal dressing and 50% as panicle fertilizer (P3), were established in an early and a late cropping season, conventional rice Yuejingsimiao 2 and hybrid rice Jingliangyouhuazhan were used as materials. In the long-term experiment, two treatments of no P application (M0) and normal P application (M1) were set up for nine consecutive years (comprising 18 seasons). Results from the short-term experiment indicated that two P reduction had no significant effect on grain yield, accumulation and translocation of dry matter, P accumulation and utilization. Among three treatments, no significant difference existed in the total and soluble P contents in the soil or in surface water. The P surplus and deficit rate were 8.7%, -35.3% and -31.8% for P1, P2 and P3 treatments, with P1 treatment achieving P apparent balance in the soil. In the long-term experiment, the relative yield under M0 treatment displayed a gradual declining trend across cropping seasons. However, the yields were comparable between two treatments in the six first seasons of three years. It could be concluded that short-term P reduction for three years would do no harm to grain yield and could reduce P loss from paddy soil in these fields with low to medium level of P content. Basal dressing of P fertilizer with half dosage would be better for achieving benefits in both grain yield and environmental protection.

Key words: Double cropping rice, Yield, Phosphorus utilization efficiency, Phosphorus balance