Effects of Different Tillage Methods on Distribution and Stability of Aggregate in Tobacco Growing Soil

In order to explore response of distribution and stability of tobacco planting soil aggregates to different tillage methods, yellow loam soil in hilly tobacco area was taken as research object．Through field positioning test, three treatments were set up : subsoiling once（T₁）, conventional rotary tillage twice（T₂）and conventional tillage once + rotary tillage once（T₃）．Effects of different tillage methods on distribution and stability of tobacco planting soil aggregates were studied, content of force-stable aggregates, content of water-stable aggregates, average weight diameter of aggregates, stability rate of water-stable aggregates, breakage rate of aggregates and unstable aggregate index were measured and analyzed．Results showed that, compared with T₃ treatment, T₁ and T₂ treatment could significantly increase number of force-stable aggregates of 0.25 to 2.00 mm aggregates in 0 to 20 cm soil layer, and number of force-stable aggregates of > 0.25 mm aggregates in ＞20 to 30 cm soil layer．Average weight diameter（ dry sieve ）value of 0 to 10 cm and ＞20 to 30 cm soil layer and average weight diameter（ wet sieve ）value of 0 to 30 cm soil layer were significantly increased in T₁ and T₂ treatment．Stability rate of water-stable aggregates in 0 to 10 cm soil layer was increased in T₁ treatment, while stability rate of water-stable aggregates in ＞10 to 20 cm and ＞20 to 30 cm soil layers was increased in T₂ treatment．The use of T₁ and T₂ treatment tillage methods would contribute to formation and stability of soil aggregates in typical hilly tobacco growing areas of Guiyang City．This study could provide theoretical support for optimizing tillage methods in hilly tobacco growing areas．