Study on the effect of nitrogen on green Chinese onion yield and N supplying target value

An experiment was conducted in Zhangqiu county of Shandong province,which is a famous region for green Chinese onion production.The experiment had 6 N treatments to study its effect on green Chinese onion yield and N supplying target value.Green Chinese onion yield increased with N fertilizer rate when enough P and K fertilizers were applied.The increment was 37.2%60.08%.The yield was highest at N 360 kg/ha.The residue N in soil increased also with increasing N application rate.The amount of surplus N of the 6 treatments in soil was 42.82,55.24,67.62,91.91,123.72 and 219.22 kg/ha,separately,presenting a serious concern for underground water pollution.The amount of apparent mineral N of soil and apparent mineral N of the organic manure were 35.11 and 43.51 kg/ha during all stage of green Chinese onion.Recovery of N fertilizer was 12.72%-35.36%.The output/input of N fertilizer was 23.91 for treatment MN1 and 9.05 for treatment MN4.The N supplying target values were N 38.05,196.20 and 233.22 kg/ha in slow growth stage,fast growth stage and cauloid inflating stage,respectively.It is very important to pay attention to yield,quality,environment and profit for green Chinese onion fertilization.