免耕和休耕改善黄绵土水稳性团聚体组成及稳定性

No-tillage and fallow improve the composition and stability of soil water-stable aggregates for cultivated loessial soils

土壤团聚体是土壤结构的基本组成单元,对土壤功能的发挥至关重要,探究耕作措施对土壤水稳性团聚体组成及稳定性的影响,有助于为耕作措施的制定和土壤健康提供理论依据。本研究基于5年的田间定位试验,分析了免耕+秸秆覆盖(NTMS)、休耕(AL)和常规耕作(CK)对黄绵土0~20 cm土壤水稳性团聚体组成和稳定性的影响,并解析其与土壤性质间的耦合关系。研究结果表明,NTMS和AL显著增加了>5 mm粒径团聚体含量、平均质量直径(MWD)、几何平均直径(GMD)和>0.25 mm粒径水稳性团聚体质量,显著降低了<0.25 mm粒径团聚体含量和分形维数(D);土壤容重(BD)、饱和持水量(SM)和毛管持水量(CMC)与土壤水稳性团聚体组成具有显著的相关关系,土壤有机质(SOM)、可蚀性因子(K)、pH和过氧化氢酶(CA)与土壤水稳性团聚体稳定性具有显著的相关关系,这7项因子可以解释土壤团聚体组成和稳定性92.0%的变异,解释率从大到小的顺序依次为CMC(33.6%)、SM(25.8%)、BD(11.4%)、SOM(8.71%)、pH(5.42%)、CA(5.27%)和K(1.86%)。免耕+秸秆覆盖耕作措施和短期休耕(3年)促进黄绵土>5 mm粒径团聚体的形成,增加土壤团聚体稳定性。

Soil aggregates are the basic units of soil structure and play a crucial role in soil functioning.Investigating the effects of tillage practices on the composition and stability of soil water-stable aggregates is beneficial for providing a theoretical basis for the development of tillage practices and soil health.A 5-year field experiment was conducted to investigate the effects of no-tillage+straw mulching(NTMS),fallow(AL),and conventional tillage(CK)on the water-stable aggregate composition and stability at 0~20 cm soil layer in cultivated loessial soils,and the relationship between these practices and soil properties was analyzed.The results showed that the implementation of NTMS and AL significantly increased the aggregate content of>5 mm particles in diameter,the mean mass diameter(MWD),geometric mean diameter(GMD),and the water-stable aggregate mass of>0.25 mm particles in diameter;but reduced the aggregate content of<0.25 mm particles in diameter and the fractal dimension(D).The composition of soil water-stable aggregates was found to be significantly correlated with soil bulk density(BD),saturated water holding capacity(SM),and capillary water holding capacity(CMC);while the stability of soil water-stable aggregates was significantly correlated with soil organic matter(SOM),erodibility factor(K),pH,and catalase(CA).The seven factors accounted for 92%of the variation in soil aggregate composition and stability,and the importance of these factors was in the order of CMC(33.6%),SM(25.8%),BD(11.4%),SOM(8.71%),pH(5.42%),CA(5.27%),and K(1.86%).No-tillage with straw mulch and shortterm fallow practices promote the formation of larger soil aggregates(>5 mm in diameter)and improve the stability of soil water-stable aggregates.