Preliminary study on rice under nitrogen, phosphorus or potassium deficiency in Fengxian District of Shanghai.

Field experiments with rice under N,P or K deficiency were carried out on three different soil types of medium-fertility farmland in Fengxian District to study effect of N,P and K fertilizer applications on rice.The results showed that N fertilizer had a remarkable effect on growth of rice population while P and K fertilizer's effects were relatively little.The descending order was N fertilizerP fertilizerK fertilizer according to the rice yield growth rate produced by fertilizer application and the yield per unit fertilizer weight.The average fertilizer utilization ratio was 22.46% in N fertilizer,10.67% in P fertilizer and 32.87% in K fertilizer.