喷灌施肥灌溉均匀性对土壤硝态氮空间分布影响的田间试验研究

在2002～2003年冬小麦生育期内进行了喷灌施肥条件下均匀系数对土壤水氮时空分布及淋失影响的田间试验。试验中，喷灌均匀系数设置低、中、高三个处理，灌溉季节内的平均喷灌均匀系数分别为72%、79%和84%，施肥灌溉均匀系数分别为71%、78%和85%。对70和90 cm深度处的土壤水势进行了监测以评估均匀系数对水氮淋失的影响，结果表明，在所研究的喷灌均匀系数范围内深层渗漏量很小。试验结果还指出，土壤硝态氮随时间和空间表现出很强的变化特征，均匀系数变化范围为23%～97%，变差系数的变化范围为0.04～1.00；灌溉季节内土壤硝态氮分布的均匀性主要取决于初始硝态氮分布的均匀程度，而喷灌均匀系数对土壤氮素的空间分布无明显影响。

Spatial distribution of nitrate in soil as affected by uniformity of sprinkler fertigation

Field experiments were conducted in the growing season of winter wheat to investigate the nitrogen distribution and deep percolation under nonuniform sprinkler fertigation. Three uniformity levels were used in the experiments with the seasonal averaged irrigation Christiansen's uniformity coefficients (CU) varying from 72% to 84% and the seasonal averaged fertigation uniformity coefficients varying from 71% to 85%. Soil water potentials at 70 cm and 90 cm depths were monitored to estimate deep percolation caused by nonuniformly applied sprinkler water. The results showed that the deep percolation was minor for the sprinkler uniformity range tested. A temporal and spatial varied distribution of nitrate in soil was observed with the uniformity coefficient ranging from 23% to 97% and the coefficient of variation from 0.04 to 1.00. The results obtained from the field experiments suggest that the spatial distribution of nitrate in the irrigation season is greatly dependent upon the initial distribution of nitrate and the impact of sprinkler fertigation nonuniformity is insignificant.