不同雨强下各生育期玉米坡耕地的侵蚀产沙研究

Runoff and Sediment Yield of Corn Plots in Different Growth Stages Under Different Rainfall Intensities

[目的]研究玉米作物对坡耕地的防蚀效果,为黄土高原坡面水土流失防治提供科学依据。[方法]采用室外人工模拟降雨试验,分析玉米在幼苗期、拔节初期、拔节中期、拔节后期、抽雄期5个不同生育期对坡耕地侵蚀产沙量和过程的影响。[结果]①随着玉米作物生长,它对坡面产流产沙的抵御作用增强,幼苗期效果微弱,抽雄期最盛,抽雄期相比裸地可减少48.5%径流量和73.7%产沙量。不同生长阶段玉米作物的减沙效果优于减流效果。②降雨的产流产沙过程呈现不断波动趋势,玉米作物使初始产流产沙时间延迟,稳定产流产沙阶段平均产流产沙量下降。雨强从40 mm/h增加到80 mm/h使产流产沙量增长率大于100%,径流系数和含沙量均增加,侵蚀过程更加剧烈。③叶面积指数与不同生育期玉米地坡面的土壤流失比率有较好的指数相关关系,可使用叶面积指数来估算不同生育期玉米地坡面的土壤流失比率,为估算年植被覆盖与管理因子C值奠定基础。[结论]随着玉米生长,其防蚀效果增强,但幼苗期和拔节初期侵蚀严重,需采取辅助措施防治水土流失。雨强增加使玉米和裸地条件下侵蚀产沙更为严重。

[Objective] The anti-erosion effects of corn on slope farmland was studied in order to provide a theoretical basis for the prevention and control of soil erosion on slope farmland in the Loess Plateau region. [Methods] An outdoor artificial simulated rain test was conducted to analyze the effects of corn on the runoff and sediment production and erosion process on slope farmland at five different growth stages, such as seedling stage, early jointing stage, mid-joint stage, late jointing stage, and tasseling stage. [Results]① With the growth of crops, the resistance of corn to runoff and sediment yield increased, this effect was the weakest in the seedling stage and the strongest in the tasseling stage. Compared with bare land, the average runoff and sediment yield of corn plot decreased by 48.5% and 73.7% respectively. The sediment reduction effect of corn in different growth stages was better than that of runoff reduction effect.② The process of runoff and sediment yield showed a continuous fluctuation trend. Corn crops delyaed the initial time of runoff and sediment yield, and the average runoff and sediment yield decreased in stable runoff and sediment yield stage. When rainfall intensity increased from 40 mm/h to 80 mm/h, the increase rate of runoff and sediment yield was more than 100%, the runoff coefficient and sediment concentration increased, and the erosion process became more severe.③ There was a good exponential correlation between leaf area index and soil loss ratio of corn slope at different growth stages. The leaf area index could be used to estimate the soil loss ratio of corn slope in different growth periods, which laid a foundation for estimating annual vegetation cover and management factor C value. [Conclusion] With the growth of corn, the anti-erosion effect of corn is enhanced, but the erosion is serious at seedling stage and early jointing stage, auxiliary measures should be taken to prevent soil and water erosion. The increase of rainfall intensity makes the erosion and sediment yield more serious under various underlying surface conditions.