四川黄壤区玉米季坡耕地自然降雨及其侵蚀产沙特征分析

为明确玉米全生育期自然降雨特征以及坡耕地产流产沙规律,以研究区自然降雨为基础,采用野外径流小区和室内分析相结合的方法,分别对横坡垄作、平作和顺坡垄作坡面玉米全生育期(苗期、拔节期、抽雄期和成熟期)的自然降雨、径流及侵蚀产沙量进行了测定。结果表明:研究区2015年玉米全生育期内雨量为676.71mm,其中成熟期侵蚀性雨量达411.71mm,占累计侵蚀性雨量的69.85%。玉米全生育期内,产流受雨量、玉米生育期显著影响,横坡垄作产沙受雨量、雨强的影响显著,而平作和顺坡垄作则受雨量、株高的影响显著;产流产沙均随玉米生育期的推进逐渐增加,且产沙受产流影响显著,横坡垄作和平作含沙量先减小后增加再减小,而顺坡垄作则先减小后增加;抽雄期横坡垄作产流显著小于顺坡垄作而产沙显著小于平作和顺坡垄作,成熟期横坡垄作产流产沙显著小于平作和顺坡垄作。研究区自然降雨条件下,雨量是影响黄壤坡耕地产流产沙的最主要因子,产沙滞后于产流;玉米成熟期土壤侵蚀最为严重,横坡垄作是防治研究区水土流失的有效途径,研究成果为山地黄壤水土流失有效防控与农业的可持续发展提供理论参考。

Characteristics of Natural Rainfall and Sediment Yield of Sloping Cropland of the Yellow Soil Area in Sichuan During Corn Growth Season

The objective of this study was to investigate the characteristics of the natural rainfall, runoff and sediment yield of sloping cropland during the whole growth period of corn. Field runoff plots and laboratory analysis were used to measure rainfall, runoff and sediment yield at different stages of the corn growth period (seeding stage, jointing stage, tasseling stage, and maturing stage) under 3 tillage practices (cross ridge planting, flat planting, and downslope ridge planting) based on natural rainfall of the study area. The results showed that the rainfall of the study area was 676.71 mm from May to August in 2015. The amount of erosive rainfall was 411.71 mm and accounted for 69.85% of the cumulative erosive rainfall at maturing stage. During the whole growth period of corn, the runoff was significantly influenced by rainfall and corn growth stages. Sediment yield under the cross ridge planting was significantly influenced by rainfall amount and intensity. However, sediment yield under flat planting and downslope ridge planting was significantly influenced by rainfall amount and corn height. The runoff and sediment yield increased with the growing of corn, and sediment yield was significantly influenced by the runoff. The sediment yield under cross ridge and flat planting decreased at first, then increased and finally decreased, while it decreased at first and then increased under downslope ridge planting. At tasseling stage, the runoff amount under cross ridge planting was significant lower than that under downslope ridge planting, while the sediment yield under cross ridge planting was significant lower than those under flat planting and downslope ridge planting. At maturing stage, the runoff and sediment yield under cross ridge planting was significantly lower than those under flat planting and downslope ridge planting. Rainfall was the main factor that influenced runoff and sediment yield of the sloping cropland under the condition of natural rainfall. The sediment yielding time was longer than that of runoff. Soil erosion at the maturing stage was the most serious among all growth stages of corn. The results indicated that cross ridge planting was an effective practice to prevent soil erosion. Therefore, this study would provide the theoretical basis for the soil erosion prevention, and sustainable development of agriculture in the yellow soil area.