Effects Of Deep Straw Returning On Physical Properties

This paper mainly study straw returning to the role of variation of soil structure、moisture and so on through straw returning experiment and training study combining,clarify the influence of straw returning to soil physical properties and crop rootgrowth.For efficient utilization of straw resources and improvement of soil structureprovide a new method.The results showed as follow:（1）Adopts two lines of the three ridge planting method, field for high volumestraw returned, study the influence of different returning straw to soil physicalproperties. At the end of the maize growth period sampling measurement, strawreturning can reduce soil bulk density, increase the soil total porosity, and the moreobvious with the increase of the straw into the contem role, Returning to1.32%themost significant change, bulk density was reduced by7.19%, total porosity increasedby6.77%. For>5mm large aggregate with lower trend, and other large aggregateparticle size has increased,0.88%relative quantity is obviously, decrease and increaserespectively by55.78%and28.65~202.86%.For0.05~0.02mm and <0.002mmmicro aggregate formation inhibition effect,0.02~0.002mm and>0.25mm microaggregate formation play a role, straw quantity1.32%processing has significanteffect. Each treatment than CK soil hygroscopic water content increased by3.04%~28.65%. Moisture characteristic curve fitting degree is higher, soil moisture and airpermeability were positively correlated.(2) In the Jilin Agricultural University field practice the same amount of strawreturning different depth processing, Research the effects of soil physical propertiesand crop root growth with different returning depth. Particle size0.05~0.02mmaggregate inhibition effect, returning a depth of0to30cm treatment effect is mostobvious, was reduced by15.1%; Particle size0.02~0.002mm and>0.25mm has apromoting effect, returning0~15cm depth processing effect is most obvious,increased by34.35%and34.35%respectively; For <0.002mm micro aggregateimpact is not big. Straw returning increased soil hygroscopic water content,0to15cm soil hygroscopic water content increase the biggest, increasing by38.68%. Eachtreatment improves the soil respiration rate and soil CO2content.(3) Using in situ test on black soil, the different straw quantity effects on soilphysical and chemical properties in different levels of soil. Three levels (0~20,20~40,40~60cm) of black soil added4%and8%of straw by4years of humification processes and the number of organic matter increased significantly,4%of the strawcan make the soil organic matter increased by31.84%~171.14%,8%of the straw tosoil organic matter increased by86.19%~265.86%. The increase of organic matterpromoted the reunion of soil, significantly increase the number of>0.25mm aggregate,improve the soil cation exchange capacity.(4) Using nylon bag incubation test, study the adding different organic materialson the influence of different soil structure. The same processing, different number ofturns, from the inner (0) to the outer layer (7), particle size of0.05~0.02mm and0.02~0.002mm in turn increases; while <0.002mm and>0.25mm is reduced in turn.Known: adding organic matter reduced particle size0.05~0.02mm and0.02~0.002mm micro aggregate content, increase the <0.002mm and>0.25mm aggregate content.The same soil, different processing, aggregate the most obvious change is for N2handling, so that the comparison between the groups, add straw powder was mostpronounced influence on soil micro aggregate content.