Mechanism of the effect of straw returning on soil moisture
To investigate the effects of different straw returning methods on soil moisture and to reveal the mechanism of the effects of straw returning methods on soil moisture,control(CK)and six treatments were set up in this study.The six treatments were straw burying and returning(SB),straw rotational tillage and returning(SRT),straw chop-ping and mixing and returning(SC),straw mulching and returning(SM),straw returning and leaving high stubble(SHS)and straw strip returning(SS),respectively.Indoor and outdoor analyses and location experiments were per-formed to measure the soil moisture indices and to analyze the correlation between the two methods.The results showed that straw returning could improve the water storage and supply capacity of the soil,which was specifically manifested as the in-crease of soil water content,saturated water holding capacity,maximum molecular water content,specific water capacity val-ue,and the SB treatment showed the best effect compared with the control.Besides,straw returning could enhance the move-ment ability of the water in the soil and increase the content of water in the soil that could be utilized by plants,which was specifically manifested as the increase of the minimum water holding capacity of the field soil,capillary water content,free water content and effective water content.Furthermore,straw returning could increase soil organic matter content,reduce the volumetric weight,increase the content of clay particles,improve the proportions of total soil pores,large soil pores and medi-um soil pores and could improve the effectiveness of soil water,and the SB treatment showed the best effect compared with the control.Soil organic matter content,soil clay particles content and the proportions of total soil pores,large soil pores and me-dium soil pores,mean weight diameter(MWD)of soil aggregates,geometric mean diameter(GMD)of soil aggregates showed significantly or highly significantly positive correlation with soil saturated water-holding capacity,field minimum water-holding capacity,coefficient of wilting,and hydraulic conductivity.Percentage of aggregate disruption(PAD)and unstable aggregate index(ELT)showed significantly or highly significantly negative correlation with soil saturated water holding capacity,free water content,wilting coefficient,and maximum molecular water content.Combined with the results such as the influence of straw returning on soil moisture characteristics and correlation analysis,the mechanism of the effect of straw returning on soil moisture can be concluded as follows:after the straws were decomposed in the soils,the soil organic matter content in-creased,the volumetric weight decreased,the specific surface area of soil particles increased greatly,the content of clay par-ticles in the soil increased,the percentages of total soil pores,large soil pores and medium soil pores increased,the soil structure was optimized,the soil's abilities of storing water and supplying water were comprehensively improved,and the soil's abilities of water absorption and utilization were strengthened.In conclusion,the method of straw burying is suitable for lands in Northeast China,and the results in this study can provide scientific guidance for farmers to choose appropriate meth-od of straw returning.
NETL
NSTL
万方数据
