玉米季横垄坡面土壤剥蚀率与径流含沙量关系

为明确玉米全生育期横垄坡面土壤剥蚀率与径流含沙量之间的关系,以川中丘陵紫色土区坡耕地为研究对象,通过野外人工模拟降雨试验,开展玉米全生育期土壤剥蚀率和径流含沙量变化特征研究,并分析土壤剥蚀率与径流含沙量之间的关系。结果表明:(1)玉米全生育期土壤剥蚀率随降雨强度的增大而增大,2.0mm/min降雨强度条件下土壤剥蚀率分别为1.5,1.0mm/min降雨强度条件下的1.87,4.59倍;同一降雨强度条件下,土壤剥蚀率在玉米生长过程中先降低后增加,苗期显著高于其他生育期。(2)不同降雨强度条件下,产沙量随玉米生育期的推进先降低后增加,苗期最大(306.6g),抽雄期最小(64.6g);除玉米抽雄期外,其他各生育期产沙量随降雨强度的增大逐渐增加,且苗期和拔节期产沙量在降雨强度间差异显著;玉米各生育期径流含沙量在降雨过程中呈波动变化的趋势,降雨强度越大,其波动幅度越强。(3)玉米全生育期土壤剥蚀率与径流含沙量呈幂函数关系,且两者间达到极显著水平。研究结果可为揭示紫色土区坡耕地水蚀机理和区域水蚀预测预报模型构建提供理论依据。

Relationship Between Soil Detachment Rate and Sediment Concentration in Runoff on Slope of Contour Tillage During Maize Growing Stages

The objective of this study was to investigate the relationship between soil detachment rate and sediment concentration of ridge contour during maize growing stages. This paper took sloping farmland of purple soil in Hilly Area of Central Sichuan basin as the research object. The filed artificial rainfall experiment was carried out for determination of characteristics of soil detachment rate and sediment concentration during maize growing stages, and to find the relationship between soil detachment rate and sediment concentration. The results showed that: (1) The soil detachment rate increased with the increasing rainfall intensity during maize growing stages, and the soil detachment rate under 2.0 mm/min rainfall intensity were 1.87 and 4.59 times greater than that under 1.0 and 1.5 mm/min rainfall intensity, respectively. During maize growing stages in the field, the soil detachment rate showed a falling-and-rising trend, and was significantly higher in the seedling stage than that in other growing stages under the same rainfall intensity. (2) Within maize growing stages, the sediment yield increased firstly and then decreased under different rainfall intensities. The largest sediment yield was (306.6 g) in the seedling stage, and the least (64.6 g) was in tasseling stage. The sediment yield increased with the increasing rainfall intensity in growing stages except for tasseling stage, while the difference was significant among rainfall intensities in seedling stage and jointing stage. The sediment concentration in runoff showed a fluctuating trend during the maize growing stages in the rainfall process, and the fluctuation range increased with the increasing rainfall intensity. (3) A power function relation was listed between soil detachment rate and sediment concentration in runoff during maize growing stages, and the correlation was significant. The results provide references for revealing the mechanism of soil erosion in sloping farmland of purple soil and the construction of regional water erosion prediction model.