Effect of Nitrogen Fertilizer Application Time on Yield, Economic Profit and Nitrogen Use Efficiency of Cotton

The study was carried out to investigate effects of nitrogen fertilizer application time on yield, economic profit and nitrogen use efficiency of cotton(Gossypium hirsutum L.) in Jianghan plain with a field experiment. The results showed that with a nitrogen application rate of 240 kg/hm2and taking cotton yield, economic profit, apparent recovery efficiency of applied N and the accumulation of NO3--N in soil into consideration, the optimal nitrogen fertilizer application time on cotton was recommended to be 40% base fertilizer + 15% seedling fertilizer +15% bud-flower fertilizer + 30% flower-boll fertilizer , at which seed cotton yield was 5 038 kg/hm2, 79.5% higher and an economic profit of 15 622 yuan / hm2compared with CK(no nitrogen fertilizer application treatment). The apparent recovery efficiency of applied N was 52.9%. Under the amount of applied N and if the equivalent N fertilizer was dressed for 2 times, cotton yield and the economic profit were not signifi- cantly affected, but nitrogen uptake of cotton plant and the apparent recovery efficiency of applied N decreased significantly.