水蚀过程中玉米生长季横垄坡面地表糙度变化及其与侵蚀量的关系

Change of soil surface roughness during maize growing season and its relationship with soil erosion amount on slope of contour tillage during water erosion process

旨为探明川中丘陵紫色土区玉米生长季横垄坡面地表糙度与侵蚀量的关系。采用野外人工模拟降雨和微小区相结合,探讨不同降雨强度(1. 0、1. 5和2. 0 mm/min)条件下,水蚀过程中玉米全生育期地表糙度和侵蚀量变化特征,并分析地表糙度与侵蚀量的关系。结果表明:1)细沟侵蚀阶段地表糙度变幅最大;苗期地表糙度最大降幅达到58. 87%,抽雄期地表糙度变幅最低。2)玉米各生育期细沟侵蚀量显著高于溅蚀和片蚀;溅蚀阶段苗期侵蚀量随降雨强度增加而增加,其他生育期变化趋势与之相反;片蚀和细沟侵蚀量在2. 0 mm/min降雨强度条件下最大;玉米苗期侵蚀量显著高于其他生育期,分别为拔节期、抽雄期和成熟期的1. 60、3. 18和1. 79倍。3)片蚀和细沟侵蚀阶段玉米各生育期初始地表糙度,地表糙度变幅和降雨强度与侵蚀量显著相关,溅蚀阶段玉米全生育期降雨强度和地表糙度变幅与侵蚀量相关性达到显著水平,玉米全生育期地表糙度变幅对侵蚀量预测效果较优。

[ Background ] The purple soil region is one of the typical areas suffering serious soil erosion in Southwest China. Serious soil erosion would surely result in the loss of sediment and the occurrence of runoff. The objectives of this study is to investigate the relationship between soil surface roughness and soil erosion amount of contour tillage during maize growing stages, providing a scientific basis for revealing the mechanism of soil surface roughness in sloping farmland of purple soil.[ Methods ] The artificial field rainfall experiment was carried out for determination of characteristics of soil surface roughness and soil erosion amount during maize growing stages. And the relationship between soil surface roughness and soil erosion amount was analyzed. A total of 36 rainfall simulation experiments were conducted in two 1 m×2 m boxes under 3 rainfall intensities (1.0, 1.5 and 2.0 mm/min) on a typical gradient of 15°.[ Results ] 1) The largest change range of soil surface roughness was in rill erosion stage, the change range of soil surface roughness reached minimum value at tasseling stage and the soil surface roughness reduced maximally at seedling stage during water erosion process (58.87%). 2) The soil erosion amount in rill erosion was significantly higher than that in splash erosion and sheet erosion. With rainfall intensity increased, the soil erosion amount at seedling stage increased during splash erosion, while that at seedling stage was opposite to the changes at other growing stages. The soil erosion amount during maize growing season reached maximum at 2.0 mm/min rainfall intensity in sheet erosion and rill erosion (218.82 g and 349.41 g). The soil erosion amount at seedling stage was 1.60, 3.18 and 1.79 times greater than that at jointing stage, tasseling stage and maturing stage, and significantly higher than other growing stages. 3) The regression equations of initial soil surface roughness, change range of soil surface roughness, rainfall intensity and soil erosion amount significantly correlated in sheet erosion and rill erosion. A significant correlation was observed between change range of soil surface roughness, rainfall intensity and soil erosion amount during splash erosion stage.[ Conclusions ] The changes of surface roughness and soil erosion amount reached maximum at seedling stage. The change of soil surface roughness could better be predicted soil erosion amount during water erosion process.