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 physical characteristics.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 meadow soil.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 five years.Among them,clay silt particles＜53 μm with shallow tillage in 10-20 cm soil layer increased by 86.21%and 14.65%,respectively,compared with no tillage and deep tillage,and deep tillage in 20-30 cm soil layer increased by 113.82%and 59.68%,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 soil layer,which was 19.43%and 20.57%on average,respectively,lower than no tillage and shallow tillage,straw mulching and straw shallow returning with significant differences(P＜0.05).The stability of aggregates was reduced due to the disturbance of continuous deep tillage to the subsoil,all of these can provide a scientific basis to improve the soil structural properties and the stability of aggregates and fertilize the soil,and the depth of tillage and straw returning should be adjusted by means of rotation in future production.
straw returningtillagewater-stable aggregatesstabilitydepth of soil
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