Effects of applying nitrogen fertilizer on sweet potato

Effects of different amount of nitrogen fertilizer on the yield of sweet potato were investigated.The results showed that: the highest yield of sweet potato was 4 095 kg/667m2(61 425 kg/hm2) by applying N 9 kg/667m2(135 kg/hm2),the increased rate was 55.65% to compare with the control treatment,reached very significant level.In this treatment,the efficiency of N fertilizer was 26.17%,partial nitrogen fertilizer productivity was 209.23 and the ratio of output and input was 2.34 and net income increased by 972 yuan/667m2(14 580 yuan/hm2).