水旱轮作条件下长期自然免耕对土壤理化性质的影响

Effects of Long-Term Natural No-Tillage on Soil Physiochemical Properties in Rice/Wheat Rotation Systems

通过实地调查，采集不同免耕年限土壤进行对比分析，研究了水早轮作条件下长期自然免耕对土壤理化性质的影响。结果表明：水早轮作条件下，不进行秸秆覆盖长期双免耕的农耕措施对土壤理化性质有较大的影响。0～15cm土层容重随免耕年限的增加而减小，免耕7～8年后趋于稳定，而15～30cm土层的容重几乎不受影响；土壤团聚度随免耕年限的增加而增加，表层增加更明显；土壤有机质、全氮、速效氮和磷含量均随免耕年限增加而逐年上升，并且有明显表聚现象，但对速效钾的影响则不明显。

Through fieldwork, investigated the effects of long-term natural no-tillage on soil physiochemieal properties in rice/wheat rotation systems from different years no-tillage soil, the results showed that： under rice/wheat rotation systems, long-term no-tillage of mulching with straws had some effects on soil physiochemical properties. Soil bulk density deereased with no-tillage years in 0- 15 cm soil layer, then stabilized after 7- 8 years, while there were no effects in 15-30 cm soil layer. Soil aggregate degree increased with no-tillage years, especially in the surface layer. Except available potassium, the contents of organic matter, total nitrogen, available nitrogen and phosphorus also increased with no-tillage years, and the surface gathering phenomenon was obviously.