【摘要】 通过春小麦田间试验,以传统耕作为对照,分析免耕不覆盖、免耕秸秆覆盖、立茬和残茬压倒4种保护性耕作措施田间输沙量、土壤团聚体、<0.01 mm物理性黏粒、<0.01 mm分散性黏粒和分散系数随年限增加的变化,研究民勤绿洲灌区保护性耕作对土壤风蚀与土壤物理性质的影响。结果表明:与传统耕作相比,保护性耕作输沙量显著减少;>1 mm团聚体作为不可风蚀颗粒的数量没有发生显著变化,保护性耕作大团聚体(>0.25 mm)含量有增大趋势、微团聚体(0.25～0.05 mm)含量有减少趋势;保护性耕作实施2年后,<0.05 mm土粒含量占比除立茬处理减少不显著外,其他保护性耕作处理均显著减少;试验第3年,传统耕作处理<0.01mm物理性黏粒含量较保护性耕作处理有减少趋势;免耕不覆盖、立茬和残茬压倒处理<0.01 mm分散性黏粒含量随年限的增加显著下降,免耕秸秆覆盖处理变化不显著;免耕不覆盖和残茬压倒处理土壤分散系数随年限的增加显著下降,免耕秸秆覆盖和立茬处理下降不显著;保护性耕作实施的第3年,各保护性耕作处理分散系数出现减小的趋势。输沙量与>1 mm团聚体、<0.05 mm土粒和<0.01mm分散性黏粒含量都有极显著的负相关关系,与0.25～0.05 mm团聚体含量呈极显著正相关关系,与1～0.25 mm团聚体、<0.01mm物理性黏粒含量和分散系数无显著的相关关系。综上所述,研究区保护性耕作能减少土壤风蚀;随年限的增加,保护性耕作土壤微结构得到改善。土壤微结构的改善有利于土壤大团聚体的形成,但这是一个缓慢的过程,在本文3年的研究时间内,还不足以对土壤风蚀产生影响。更多还原

【Abstract】 A spring wheat filed experiment was conducted to investigate the effects of conservation tillage on soil wind erosion and soil physical properties by analyzing the changes of field sediment discharge, soil aggregate composition, <0.01 mm physical clays, <0.01 mm dispersible clays, and dispersion coefficient with increasing year in Minqin oasis irrigational area. Four kinds of conservation tillage were adopted in this study, 1) no-tillage with no stubble(NT), 2) no-tillage with stubble(NTS), 3) standing stubble(SS), and 4) stubble overwhelm(SO), while conventional tillage(CT) as control. The results showed that compared with CT, conservation tillage treatments decreased significantly sediment discharge, the quantity of >1 mm soil aggregates as impossible wind erosion particles changed insignificantly, macro-aggregates(>0.25 mm) increased, and micro-aggregates(0.25–0.05 mm) decreased. In the second year of the test, <0.05 mm soil particles were all decreased significantly in other conservation tillage treatments except no significant decrease in SS treatment. In the third year of the test, <0.01 mm physical clays decreased in CT compared with all conservation tillage treatments, <0.01 mm dispersible clays decreased significantly with increasing year under NT, SS and SO treatments, while no significant change under NTS treatment, soil dispersion coefficient decreased significantly with increasing year under NT and SO treatments, while no significant decrease under NTS and SS treatments. In the third year of the test, dispersion coefficient decreased in all conservation tillage treatments, sediment discharge had extremely significant negative correlation with >1 mm soil aggregates, <0.05 mm soil particles and <0.01 mm dispersible clays, extremely significant positive correlation with 0.25–0.05 mm soil aggregates, but no significant correlation with 1–0.25 mm soil aggregates, <0.01 mm physical clays, and dispersion coefficient. In conclusion, in the study area, conservation tillage can reduce soil wind erosion, improve soil microstructure gradually, which is beneficial to formation of soil macro-aggregate, but this is a slow process, cannot influence soil wind erosion obviously in three years.更多还原