不同坡度和不同生育期的谷子坡耕地入渗特征

坡度和作物生育期是影响坡耕地土壤入渗性能的关键因素,作物生长导致土壤特性及根系变化进而影响坡面入渗过程。通过人工模拟降雨试验,设计4个坡耕地坡度(3°,5°,10°,15°)及2个降雨强度(40,80 mm/h),在谷子4个生育期(拔节初期、拔节中期、抽穗初期、灌浆初期)开展试验,探究坡度和生育期对谷子坡耕地土壤入渗特征的影响机制,并结合入渗模型(Horton、Kostiakov、Philip模型)对谷子坡耕地土壤水分入渗过程进行拟合并评价其适用性。结果表明:(1)随坡度增加土壤入渗能力下降,与3°相比,15°坡耕地土壤稳定入渗速率、平均入渗速率及累积入渗量分别减小30.76%~52.38%,21.28%~37.50%和22.51%~43.55%。(2)随着谷子生育期的延长,土壤入渗能力显著增加,与拔节初期相比,灌浆初期时土壤稳定入渗速率、平均入渗速率及累积入渗量分别增加23.81%~80.00%,20.83%~40.00%,17.84%~54.10%,表现为拔节初期<拔节中期<抽穗初期<灌浆初期。(3)通过对入渗速率实测值进行拟合,Horton模型对坡耕地土壤入渗过程拟合最好,且模型拟合参数具有物理意义。研究结果可为增加坡耕地降雨入渗、提高水分利用效率、减少坡耕地水土流失提供理论依据。

Infiltration Characteristics of Millet Slope Farmland with Different Slope Gradient and Different Growth Period

Slope and crop growth period are the key factors affecting the soil infiltration performance of sloping farmland, and crop growth can result in soil characteristics and root changes, which further affect the slope infiltration process. Through artificial simulated rainfall experiments, the slopes (3°, 5°, 10° and 15°) and 2 rainfall intensities (40 and 80 mm/h) of four slope cultivated land were designed, and the experiments were carried out in four growth stages of millet (early jointing period, middle jointing period, early heading period, early pustulation period) to explore the influence mechanism of slope and growth period on soil infiltration characteristics of millet slope farmland, and combined with the infiltration model (Horton, Kostiakov and Philip models) to evaluate the applicability of soil moisture infiltration process in cultivated land of millet slope. The results showed that: (1) The soil infiltration capacity decreased with the increase of slope, and compared with the slope of 3°, the stable infiltration rate, average infiltration rate and cumulative infiltration rate of the soil in farmland of 15° slope decreased by 30.76%~52.38%, 21.28%~37.50% and 22.51%~43.55%, respectively. (2) With the extension of millet growth period, soil infiltration capacity increased significantly, and compared with the early jointing stage, the stable infiltration rate, average infiltration rate and cumulative infiltration amount of soil in the early filling stage increased by 23.81%~80.00%, 20.83%~40.00% and 17.84%~54.10%, respectively, showing that the early jointing period < the middle jointing period < the early heading period < the early pustulation period. (3) By fitting the measured values of infiltration rate, the Horton model could best fit the soil infiltration process of slope farmland, and the fitting parameters of the model had physical significance. The research results can provide a theoretical basis for increasing rainfall infiltration, improving water use efficiency and reducing water and soil loss in sloping farmland.