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作 者 ：张晴雯, 陈尚洪, 刘定辉, 黄新君

期 刊 ：核农学报 2016年 30卷 7期 页码：1395-1403

关键词：坡耕地；农业措施；径流系数；径流曲线数；土壤可蚀性；

Keywords:sloping cropland, agricultural practice, runoff coefficient, curve number, soil erodibility,

摘 要 ：为明确侵蚀性降雨条件下不同农业措施对玉米季坡耕地水沙过程的影响及减沙效应,通过自然降雨条件下径流小区观测试验,研究顺坡耕作(CK)、横坡垄作(CT)、横坡垄作+秸秆覆盖(CT+SM)、横坡垄作+地膜覆盖(CT+PM)、横坡垄作+有机质输入(CT+OM)5种农业措施对紫色土玉米季坡耕地径流深、径流系数、径流曲线数、产沙量、土壤可蚀性指标的综合影响。结果表明,历次降雨事件CK径流系数变幅为18.89%~32.23%,CT+OM和CT+PM显著削减了径流量和产沙量,径流量较CK减少15%~35%、泥沙量减少12%~75%。土壤可蚀性指标随降雨量和径流量增加均呈增加趋势,但增加幅度随着降雨量或径流量的增加而减小;土壤可蚀性与地表径流量之间呈幂函数递增关系,确定系数R²为0.70~0.87(p<0.05);土壤可蚀性与降雨量呈对数曲线关系,R²为0.85~0.91(p<0.05)。历次降雨横坡各处理土壤可蚀性指标(K_w)显著低于顺坡垄作,CT 和CT+OM的K_w均值分别为0.025 kg·m^-2·mm^-1和0.023 kg·m^-2·mm^-1,与CK相比平均分别减小17%和24%;CT+PM和CT+SM的K_w值最小,均值分别为0.021 kg·m^-2·mm^-1和0.018 kg·m^-2·mm^-1,与CK相比分别减小29%和38%。综上,横坡垄作增加地膜覆盖或秸秆覆盖是控制紫色土玉米季坡耕地地表径流、降低土壤可蚀性的有效措施。本研究为控制紫色土玉米季坡耕地水土流失、削减农业面源污染负荷提供了理论依据。

Abstract:To understand combined effects of erosive rainfall and tillage implementation onwater erosion processes and effects of sediment reduction from sloping farmland during the maize growing season, a field plot experiment was conducted to evaluate the potential benefits of surface protection tillage under natural rainfall conditions including five management practices, which were conventional tillage system as control (CK), contour tillage without surface cover (CT), CT with addition of organic matter (CT+OM), CT with a cover of plastic (CT+PM), and CT with a wheat straw mulching (CT+SM), respectively. Results showed that runoff volume and sediment concentration from surface covered plots were significantly smaller than that from control plots. Compared with conventional sloping tillage systems, CT, CT+OM, CT+PM, and CT+SM decreased annual runoff discharge 15%, 26%, 36% and 35%, and reduced sediment yields 12% to 61%, 25% to 70%, 38% to 70%, and 46% to 75%, respectively. Soil erodibility increased with rainfall amount and runoff discharge, while its increase rate decreased and intended to stable ones. We proposed a power model were proposed to estimate the increase tendency between soil erodibility and runoff discharge with R² of 0.70 to 0.87 (p<0.05). While a logistical model was proposed to fit relationship between soil erodibility and rainfall amount with R² of 0.85 to 0.91 (p<0.05). Soil erodibility indicators under conventional sloping tillage systems was 0.029 kg·m^-2·mm^-1. Soil erodibility values under CT and CT+OM were 0.025 and 0.023 kg·m^-2·mm^-1, and decreased 17% and 24% compared with CK. Soil erodibility values under CT+PM and CT+SM were lower than 29% and 38% than those of CK, with average values of 0.021and 0.018 kg·m^-2·mm^-1, respectively. The above results indicated that surface protections by crop straw mulching or plastic cover combined with contour tillage are to be the good management practices to reduce soil loss by water erosion in regions of intense agricultural activity. This study provides a theoretical basis for the control of soil and water loss, and reduction of agricultural non-point sources pollution from sloping farmland during maize growing season.

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