滴灌棉田氮肥用量对土壤无机氮的动态影响

通过南疆滴灌条件下N肥田间试验,研究了施用N肥对棉花生育期土壤无机N累积及收获后土壤NO3--N残留的影响.棉花生育期土壤无机N的累积规律是:花期以后,施肥量较高(N 225～337.5 kg/hm2)时,土壤无机N以NO3--N为主要形式累积于表层0～40 cm土壤中.棉花生育期施肥量影响收获后耕层土壤残留NO3--N.根据各施肥处理土壤NO3--N残留状况及产量,确定N 180～225 kg/hm2为南疆滴灌棉田土壤NO3--N发生少量累积同时获得高产的适宜施肥量范围.

Effect of Nitrogen Fertilizer on Dynamics of Soil Mineralized Nitrogen in Cotton Field under Drip Irrigation

Based on a field experiment of nitrogen fertilizer application in cotton fields under drip irrigation in South Xinjiang, effects of nitrogen application on dynamics of soil Nmin during cotton growth season and soil NO3--N residue after harvest of the crop were studied. Results showed that with the nitrogen application rate ranging between N 225 ~ 337.5 kg/hm2, soil Nmin (NO3--N mainly) accumulated mainly in the 0 ~ 40 cm soil layer after the flowering stage and the amount of NO3--N residue in the plow layer after the crop was harvested varied with application rate. Based on soil NO3--N residues and cotton yields of various treatments, an optimum range of nitrogen application rate is determined to be in the range from N 180 to 225 kg/hm2 for cotton under drip irrigation to gain high yield while leave less NO3--N residue in the soil in South Xinjiang.