冀西北旱作春玉米秸秆还田模式对土壤团聚体稳定性的影响

Effect of Spring Maize Straw Returning Model in Northwest Hebei Province on Soil Aggregation Stability

[目的]研究冀西北旱作区春玉米秸秆还田对土壤团聚体稳定性的影响,优化适宜旱作区春玉米秸秆还田模式。[方法]采用连续3年田间定位试验,设计秸秆还田翻耕(JF)、秸秆还田旋耕(JX)、秸秆还田大垄轮播(JL)3种还田模式,分析土壤不同粒径团聚体质量比、平均重量直径(MWD)和几何平均直径(GMD)。[结果]冀西北旱作区春玉米农田土壤以0.25~0.50 mm团聚体占比最高,在26.28%~31.84%,其次为>1.00~2.00 mm团聚体,<0.25 mm团聚体占比最低。秸秆还田能显著提高>1.00 mm团聚体比例(P<0.05),增幅顺序为JX>JL>JF,JF、JL、JX处理比CK土壤MWD分别提高了10.59%、12.94%、17.06%,土壤GMD分别提高了15.31%、16.33%、18.37%。秸秆还田后春季土壤团聚体大颗粒占比下降,微颗粒占比升高,稳定性下降。秸秆还田显著提高0~20 cm土层>1.00~2.00 mm团聚体占比,增加土壤团聚体稳定性,提高>20~40 cm土层0.25~0.50 mm和<0.25 mm团聚体占比,降低土壤团聚体稳定性。[结论]秸秆还田模式通过对秸秆的破碎程度、有机碳输入、影响微生物酶活性调节土壤团聚体结构及稳定性,冀西北旱作区春玉米秸秆还田旋耕对土壤团聚体稳定性提高最显著。

[Objective]To study the effect of the method of returning maize straw(to the field)on soil aggregation stability in northwest Hebei Province and optimize the suitable mode of spring corn straw returning.[Method]A 3-year fixed-site straw returning experiment was conducted.Three methods of returning straw to the field were set up,including tillage(ploughing,JF),rotary tillage(JX)and large ridge rotation(JL),and analyze the aggregate mass ratio,average weight diameter(MWD)as well as geometric mean diameter(GMD).[Result]The soil of spring corn farmland in the arid region of northwest Hebei Province had the highest proportion of 0.25-0.50 mm aggregates,with a mass ratio between 26.28%and 31.84%,followed by>1.00-2.00 mm aggregates,and the lowest proportion of<0.25 mm aggregates.The proportion of straw agglomeration increased significantly(P<0.05),and the order of increase was JX>JL>JF.The JF,JL and JX treatments increased by 10.59%,12.94%and 17.06%,and the soil GMD increased by 15.31%,16.33%and 18.37%,respectively.After returning straw to the field,the proportion of large particles in soil aggregates decreased in spring,while the proportion of micro particles increased and the stability decreased.Returning straw significantly increased the proportion of>1.00-2.00 mm aggregates in the 0-20 cm soil layer,increased soil aggregate stability,increased the proportion of 0.25-0.50 mm and<0.25 mm aggregates in the>20-40 cm soil layer,then reduced soil aggregate stability.[Conclusion]The mode of straw returning regulates the structure and stability of soil aggregate through the crushing degree,organic carbon input and the influence of microbial enzyme activity,meanwhile improves the stability of spring maize straw returning in the dry farming area of northwest Hebei Province.