Nutrient management and balanced fertilization on main crops in Ningxia province

Two experiments on determining optimal K rates for cabbage and rice were conducted in 2012 in Ningxia Province. The experiment on cabbage in Wuzhong City showed that along with the recommended application of 300 kg N and 150 kg P₂O₅/ha, application of 75-300 kg K₂O/ha produced 3.2 to 5.9 t/ha (13 to 24%) more yield and 548 to US$972 more benefit than without K application. The optimal rate of K application was determined as 150 kg K₂O/ha, which also resulted in better quality cabbage crop with high vitamin C and soluble sugar contents, and high total soluble solids.

For rice grown in Lingwu City, application of 30 to 60 kg K₂O/ha increased rice yield by 10 to 11%, but further increase in K rates (>60 kg K₂O/ha) resulted in less yield increase (0.4 to 2%). The highest rice yield was obtained with the application of 270 kg N, 90 kg P₂O₅ and 60 kg K₂O/ha. Economic analysis showed that the highest income ($183/ha) was obtained with the application of 30 kg K₂O/ha. Ningxia-NMBF