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试验于2011年通过对玉米全生育期土壤容重和团聚体的测定,分析4种黑土农田耕作方式土壤结构季节变化。结果表明:从播种到收获,传统耕作平翻(MT)和旋松(Rot)在0~20 cm土层土壤容重逐渐增大。保护性耕作少耕(RT)垄沟深松后(6月)土壤容重降低且显著低于其他耕作方式,免耕(NT)土壤容重季节差异不显著。各耕作方式1~2 mm与0.25~0.5 mm粒级团聚体季节差异不显著,>2 mm团聚体平均含量表现为NT>RT>MT>Rot,且NT更容易形成>5 mm团聚体。各耕作方式>0.25 mm水稳定性团聚体数量(WR0.25)均随时间推移逐渐减少。MT土壤团聚体平均重量直径(MWD)季节差异不显著,10~20 cm土层几何平均直径(GMD)则表现为降低趋势,分形维数随时间推移表现出先增加后降低趋势。Rot的MWD和GMD季节变化均较小。在0~10 cm土层,RT的MWD与GMD先增加后降低,分形维数季节性变幅较大。NT处理8月份土壤团聚体的MWD和GMD最大,在0~20 cm土层,NT方式下WR0.25、MWD和GMD均大于其他耕作方式,而分形维数则小于其他耕作方式且季节变化差异不显著,NT土壤结构季节变化更稳定。
In 2011, the soil bulk density and aggregates in the whole growth period of maize were measured to analyze the seasonal changes of soil structure in four black soil cultivation ways. The results showed that from sowing to harvesting, the bulk density of soil in 0-20 cm soil layer increased with MT and Rot. After tillage and tillage with low tillage furrows (June), the soil bulk density decreased significantly and was significantly lower than other tillage practices. There was no significant difference in NT bulk density between treatments. There was no significant difference in seasonal aggregations between 1 ~ 2 mm and 0.25 ~ 0.5 mm aggregates for each tillage method. The average content of> 2 mm aggregates was NT> RT> MT> Rot, and NT> 5 mm aggregates were more likely to form. Tillage> 0.25 mm water stable aggregates (WR0.25) decreased over time. The seasonal difference of average weight diameter (MWD) of MT aggregates was not significant. The geometric mean diameter (GMD) of 10-20 cm soil layer showed a decreasing trend while the fractal dimension increased firstly and then decreased with the passage of time. Rot MWD and GMD seasonal changes are small. In 0 ~ 10 cm soil layer, the MWD and GMD of RT first increased and then decreased, and the seasonal variation of fractal dimension was larger. In NT, the MWD and GMD of soil aggregates in August were the largest. In NT 0 ~ 20 cm soil layer, WR0.25, MWD and GMD were greater than those of other tillage methods, but the fractal dimension was less than that of other tillage patterns and the seasonal variation Not significant, NT soil structure more stable seasonal changes.