Soil testing and formula fertilization index for early rice in Fujian Province

Based on the results of 135 field experiments of early rice response to N, P and K fertilization in recent years, soil testing and formula fertilization indices for early rice in Fujian Province were developed. The results show that the average contribution rate of soil nutrients to rice is 73.5%, the average increased yield of N, P and K applications are 18.1%, 5.4% and 8.6% respectively, and the soil contribution rate and the increased efficiencies of N, P and K applications are closely related to soil fertility levels. The critical indices of alkali-hydrolyzable nitrogen, Olsen-P and available K for high yield of early rice in mountainous areas are 212 mg/kg, 26 mg/kg and 116 mg/kg respectively, and the indices in coastal areas are 203 mg/kg, 22 mg/kg and 104 mg/kg respectively, which indicate that the indices in coastal areas are obviously lower than those in mountainous areas. In general, the maximum application rates to early rice are N 166 kg/ha, P2O5 69 kg/ha and K2O 113 kg/ha, and the economic application rates are N 134 kg/ha, P2O5 35 kg/ha and K2O 78 kg/ha. However, the fertilization recommendations are dependent on production areas and soil fertility levels. The regression equations established between soil testing values and fertilization recommendations of N, P and K are satisfied with the purpose of soil testing and fertilization.