Nutrient Management Strategies for Guangxi

Laibin and Fushui counties were selected as long-term monitored village sites in 2002. In past years, soil nutrient limitations were determined and verified, and soil nutrient variability maps were developed. In 2005, the project continued its study of the influence of balanced fertilization (BF) on crop yields.

At Fushui, the residual effect of the previous years application of sulfur (S), magnesium (Mg), boron (B), and zinc (Zn) was pronounced for citrus yield and quality. The optimum treatment increased orange yield by 11%, 16.8%, 15.3%, and 12% compared to the - Mg, - S, - B, and - Zn treatments, respectively. The residual fertility also influenced fruit quality as measured by vitamin C content, soluble sugar content, reducing sugars and acid contents, and percent edible portion. It is likely unnecessary to apply secondary and micronutrients each year after deficiencies are corrected, but farmers should rely on soil testing to monitor soil nutrient availability.

Research in Laibin County examined the effect of omitting potassium (K) in corn, sweet potato, and buckwheat, which is the traditional practice for the region. Corn yield was increased by 960 kg/ha (+11.8%) using a nitrogen (N), phosphorus (P), K rate of 225-90-203 kg/ha and sweet potato yield by 690 kg/ha (+13.5%) using 120-90-300 kg/ha. In buckwheat fertilized with 120-45-150 kg/ha, yield and net income were increased by 221 kg/ha (+30.1%) and US$137/ha, respectively.

Demonstration and education programs at the experimental sites have effectively promoted balanced use of fertilizers. Guangxi-NMS02