Nutrient Management Strategies for Hainan

Soil nutrient limitations in two monitored villages were identified in 2003 through soil testing and results were subsequently digitized as nutrient variability maps in 2004. Field trials were conducted and the information obtained will be applied to a national information systems database which should assist decision making by both industry and government. In addition, the study provides much guidance for developing fertilizer recommendations and nutrient management systems for these two locations.

Rice trials verified soil testing results and found nitrogen (N) and potassium (K) to be the major yield-limiting factors. In trial 1, the optimal treatment of 260-123-180 kg N-P₂O₅-K₂O/ha significantly increased rice yield by 1,407 kg/ha (28%) compared to the – K treatment and by 2,115 kg/ha (49%) compared to the – N treatment. Similarly, in trial 2, application of 224-175-174 kg/ha significantly increased rice yield by 1,164 kg/ha (17%) compared to the – K treatment and by 2,044 kg/ha (35%) compared to the – N treatment. The addition of P resulted in a yield response in trial 2, but not in trial 1. The optimal treatments achieved much higher nutrient use efficiencies and net incomes for farmers. This balanced fertilization technology is ready to be extended to areas with similar conditions on the island. Hainan-NMS01