华北平原春玉米滴灌均匀系数对土壤水氮时空分布的影响

【目的】研究滴灌均匀系数及土壤特性对土壤水氮时空分布的影响，定量评价现行标准的适宜性。【方法】试验在华北平原进行，供试作物为春玉米，滴灌均匀系数（CU）设置0.66（低）、0.81（中）和0.99（高）3个水平，灌水量设置灌溉需水量的50%（低）、75%（中）和100%（高）3个水平，监测不同生育阶段的土壤水分和硝态氮含量。【结果】土壤含水量均匀系数在生育期内大于0.85（2009年）和0.80（2010年），低灌水均匀系数处理与中、高灌水均匀系数处理没有明显区别，远大于滴灌均匀系数（0.66），初始含水量均匀系数的影响大于滴灌均匀系数，灌水量的影响较小。滴灌均匀系数对硝态氮均匀系数的影响不显著。【结论】在华北平原半湿润地区，滴灌均匀系数不是影响春玉米生育期内土壤水氮分布的主要因素，现行微灌均匀系数标准（CU≥0.80）可适当降低，以降低系统投资。

The Effects of Drip Irrigation Uniformity on Spatial and Temporal Distributions of Water and Nitrogen in Soil for Spring Maize in North China Plain

【Objective】The objectives of this study were to investigate the effects of drip irrigation uniformity and soil properties on the spatial and temporal variability of water and nitrogen in the soil and to quantitatively evaluate the suitability of current design standard of drip irrigation uniformity.【Method】Field experiments were conducted on drip irrigated spring maize  (Zea mays L.) in north China plain. Three Christiansen uniformity coefficients (CU) of 0.66 (low), 0.81(medium), and 0.99 (high) and three levels of water application at 50%, 75%, and 100% of the irrigation requirement were used. Soil water and nitrogen content were periodically measured during the growing seasons of spring maize.【Result】The result indicated that the uniformity coefficient of soil water content was higher than 0.85 in 2009 and higher than 0.80 in 2010. The low uniformity treatment did not produce a uniformity coefficient of soil water content that was significantly different from the medium and the high uniformity treatments. For the low uniformity treatment, the uniformity of soil water content was considerably higher than its irrigation uniformity (0.66). The influence of the uniformity of initiate soil water content was more important than the uniformity of water application and irrigation amount. Drip irrigation uniformity imposed an insignificant influence on the uniformity coefficients of nitrate content.【Conclusion】The results suggested that drip irrigation uniformity was not the main factor influencing the spatial and temporal variability of soil water and nitrogen for spring maize in the semi-humid regions such as the north China plain. The current design standard of drip irrigation uniformity coefficient (CU≥0.80) could be fairly lowered to reduce the initial cost of drip irrigation systems.