保护性耕作对内陆河灌区春季麦田不可蚀性颗粒的影响

Effects of Different Tillage Treatments on Unerodible Soil Particles of Wheat-field in Spring in Inland Irrigation Region

通过室内风洞试验研究了甘肃省河西地区在不同耕作措施条件下对土壤表层（0～5cm）不可蚀性颗粒（粒径≥1mm的团聚体及粗砂砾）含最的影响及不可蚀性颗粒含量与风蚀量、起动风速的相关关系。结果表明：免耕、免耕秸秆覆盖、传统耕作、秸秆翻压处理的不可蚀性颗粒（粒径≥lmm的团聚体及粗砂砾）的含量分别高于对照处理（春小麦传统耕作），说明这一地区春小麦改种冬小麦并采取保护性耕作对增加不可蚀性颗粒效果明显，以免耕秸秆覆盖（NTS）效果最好．不仅增加了不可蚀性颗粒含量，同时降低了易蚀性颗粒含量。不同耕作措施土壤表层（0～5cm）不可蚀性颗粒含量与风蚀量之间存在显著的相关关系，随着不可蚀性颗粒含量的增加风蚀量呈递减趋势而起动风速呈递增趋势。因此．在甘肃省河西地区春小麦改种冬小麦并采取免耕、秸秆覆盖、秸秆翻压等保护性耕作措施可增加表土层（0～5cm）不可蚀性颗粒含量．从而有效地减低该地区农田土壤风蚀发生的可能性。

The affects of different tillage patterns on the unerodible soil particles of surface （0～5 cm）soil have been studied in inland irrigation region. The results showed that no-till with no stubble （N）, no-till with stubble retention （NTS）, conventional till with stubble incorporating （TIS） and conventional till （T） increased the mass of unerodible soil particles of surface （0 ～ 5 cm）soil significantly compare to conventional till for spring wheat （SWT）. Therefore, Converting spring wheat to winter wheat increased the mass of unerodible soil particles of surface （0～5 cm）soil significantly, and no-till with stubble retention （NTS） also decreased the erodible soil particles. The relationship among the mass of unerodible soil particles of surface （0～5 cm）soil , the wind-blownmass and critical wind speed also discussed respectively in the experiment. Results indicated that there was significantly negative relationship between the mass of unerodible soil particles of surface （0～5 cm）soil and wind-blownmass. With the mass of unerodible soil particles of surface （0～5 cm）soil increasing the critical wind speed decreased. Therefore, winter wheat cultivation with conservation tillage can reduce the possibility of wind erosion because of the mass of unerodible soil particles improving in this region.