微润灌施下不同氮肥浓度对土壤入渗特性的影响

Effects of Different N Fertilizer Concentrations on Soil Infiltration Characteristics Under Moistube Irrigation

以黏壤土为试材,采用室内土箱模拟试验,设定土壤容重为1.30g·cm^(-3)、压力水头为1.5m、微润管埋深为15cm、氮肥浓度为0(对照)、300、600、900、1200mg·L^(-1)的5组处理,研究了不同氮肥浓度下的水分入渗过程,以期得到微润灌溉施肥条件下水分运移规律,为微润灌溉水肥一体化技术提供参考依据。结果表明:与清水处理组相比,施加氮肥处理组的累积入渗量均不同程度增大,累积入渗量随氮肥浓度的增大呈先增后减的规律,900mg·L^(-1)是其拐点;累积入渗量随时间的变化符合Kostiakov入渗模型;初始入渗速率与氮肥浓度呈正相关关系,1200mg·L^(-1)的处理组入渗速率衰减最快;氮肥浓度对湿润体形状无影响,湿润体横剖面形状皆为以微润管为中心的近似椭圆形;湿润锋垂直向下方向运移距离最大,其次是水平向右方向,最后是垂直向上方向;湿润锋在各方向的运移距离均随氮肥浓度的增加呈现先增大后减小的规律;各处理灌水均匀度都较高。综合累积入渗量和湿润锋运移情况,得到最适宜浓度范围为600~900mg·L^(-1)。

The clay loam soil was used as the test material,and the soil capacity was 1.30g·cm^(-3),the pressure head was 1.5m,the burial depth of the micro-wet pipe was 15cm,and the nitrogen fertilizer concentration was 0(control),300,600,900,1200mg·L^(-1).The water infiltration process under different nitrogen fertilizer concentrations was investigated,in order to obtain the water transport pattern under the fertilization conditions of moistube irrigation and to provide reference for the waterfertilizer integration technology of moistube irrigation.The results showed that compared with the clear water treatment group,the cumulative infiltration rate of the nitrogen fertilizer treatment group increased to different degrees,and the cumulative infiltration rate increased and then decreased with the increase of nitrogen fertilizer concentration,and the inflection point was 900mg·L^(-1).The change of the cumulative infiltration rate over time was in accordance with the Kostiakov infiltration model.The initial infiltration rate was correlated with the N fertilizer concentration,and the infiltration rate of 1200mg·L^(-1)treatment group declined the fastest;the N fertilizer concentration had no effect on the shape of the wetted body,and the shape of the wetted body cross-section was approximately elliptical with the micro-wetted tube as the center;the transport distance of the wetted front was the largest in the vertical downward direction,followed by the horizontal right direction,and finally the vertical upward direction;the transport distance of the wetted front in all directions showed a pattern of increasing and then decreasing with the increasing of the N fertilizer concentration;the uniformity of irrigation was high in all treatments.The optimum concentration range was 600-900mg·L^(-1)by combining the cumulative infiltration and wetting front transport.