覆盖和耕作对黄土高原冬小麦土壤入渗特性的影响

Impact of Different Tillage Method on Infiltration Character to Winter Wheat in the Loess Plateau

用人工模拟降雨器对黄土高原冬小麦收获后6个耕作措施:不翻耕(NT),不翻耕+覆盖(NTC),浅翻耕(LT),浅翻耕+覆盖(LTC),深翻耕(DT),深翻耕+覆盖(DTC)处理下土壤的入渗进行了研究,测定了土壤表面结皮、粗糙度等指标因子。结果表明,在模拟降雨强度为66 mm/h的条件下,覆盖处理的稳定入渗率>60 mm/h,降雨开始的40 m in内,平均入渗量>93%;深翻耕(DT)的稳定入渗率(26.4 mm/h)是浅翻耕(LT)(13.0 mm/h)的2倍,是不翻耕(NT)(6.4 mm/h)的4.1倍,降雨历时20m in时,深翻耕(DT)和浅翻耕(LT)分别比不翻耕处理(NT)减少径流28%和7%,40 m in时,浅翻耕(LT)和不翻耕(NT)处理径流量相当,深翻耕(DT)比这两个处理减少径流30%左右,土壤翻耕后在前期能提高土壤的入渗率,表现出经长年耕作后土壤退化的强烈特征,是“耕地越深,入渗越快”观念的根源;地表结皮是影响降雨入渗的主要因素,覆盖等保护性耕作更有利于土壤入渗。

Infiltration characteristics of a Heilu soil were determined using simulated rainfall （rainfall intensity is 66 mm/h） under six tillage methods： no-till （NT） ;no-till with stubble retention （NTC） ; till with shallow depth （LT, 10cm） ; till with shallow depth with stubble retention （LTC）; till with deep depth （DT,20 cm） ;Till with deep depth with stubble retention （DTC）. Soil surface cover, roughness and crust development was measured. The resuits showed that cumulative rainfaU infiltrated to soil was over 93% at the beginning of rainfall run 40 min under stubble retention, the last or steady infiltration rate 〉 60 mm/h. Tillage increased rainfall infiltration at first rainfall run; the last or steady infiltration rate under DT treatment （26.4 mm/h） is 2 times than under LT treatment （12. 96 mm/h）, while 4 times than under NT treatment （6.35mm/h）. When rainfall ran 20 rain, DT treatment increased infiltration by 21% and 28%, compared with under LT and NT treatment, when at 40 min, by 31% and 33%. The results can provide some parameters for infiltration model and benefit to farming systems.