耕作与秸秆还田深度变化对不同土层团聚体稳定性的影响

耕作和秸秆还田可以改变土壤理化性状，影响土壤团聚体的稳定性。采用田间定位试验，研究耕作与秸秆还田深度变化对旱地草甸土不同深度土层水稳性团聚体稳定性的影响，为科学开展秸秆还田培肥土壤提供依据。结果表明：土壤团聚体稳定性受>2000μm粒径大团聚体影响较大，连续5年翻耕显著降低了表层（0～20 cm）土壤>2000μm粒径水稳性大团聚体的占比，增加了53～250μm微团聚体和<53μm黏粉粒的比例。浅翻（ST）和秸秆浅翻还田（STS）与深翻（DT）和秸秆深翻还田（DTS）分别对10～20和20～30 cm土层黏粉粒的增加影响较大，其中，10～20 cm土层ST较免耕（NT）和DT处理分别增加86.21%和14.65%,20～30 cm土层DT较NT和ST处理分别增加113.82%和59.68%，差异显著（P<0.05）；连续翻耕由于对亚耕层（20～40 cm）的频繁扰动，导致250～2000μm粒径团聚体的稳定性降低，DT较NT和ST与DTS处理较覆盖免耕（NTS）和STS处理分别平均降低19.43%与20.57%，且差异显著（P<0.05）。研究结果表明，连...

Effects of different tillage and straw returning depths on soil aggregate stability of different soil layers

Tillage and straw returning could change the stability of soil aggregates and physicalcharacteristics. The field positioning experiment was conducted to study the influence of tillage and straw returning depth on the stability of soil water-stable aggregates so as to provide a scientific basis for straw returning depth on dry meadowsoil. The results showed that stability of aggregates was affected by the proportion of macro-aggregates with grain size >2000 μm. The water-stable macro-aggregates with grain size >2000 μm in 0-20 cm soil layer was significantly decreased but contents of 53-250 μm micro-aggregates and clay silt particles <53 μm were increased with constantly tillage in fiveyears.Amongthem，clay silt particles <53μm with shallow tillage in 10-20 cm soil layer increased by 86.21% and14.65%，respectively，compared with no tillage and deeptillage， and deep tillage in 20-30 cmsoil layer increased by 113.82% and59.68%，respectively，compared with no tillage and shallow tillage(P<0.05).Deep tillage had a great impact on the reduction of 250-2000 μm particle size aggregates in 20-40 cm soillayer，which was19.43% and 20.57% onaverage，respectively，lower than no tillage and shallowtillage，straw mulching and straw shallow returning withsignificantdifferences( P<0.05).The stability of aggregates was reduced due to the disturbance of continuous deep tillage to thesubsoil，all of these can provide a scientific basis to improve the soil structural properties and the stability of aggregates and fertilize thesoil，and the depth of tillage and straw returning should be adjusted by means of rotation in future production.