Effect Of Different Straw-Incorporation Methods On Soil Water Characteristics And Soil Structure

Laboratory test was done to study the effects of three straw treating manners (i.e. cut, aminated or mixed with inorganic soil amendment) on soil infiltration, evaporation, soil water retention and supply capacities as well as the soil aggregate and porosity structure. Results show that:(1) The decomposition rate of finely cut straws was obviously higher than the long straws after they were blended with soil. Amination had great effect on the straw decomposition rate. The application of inorganic soil amendments reduced the mineralization velocity of the organic carbon.(2) The finely cut and aminated straws added into soil can observably reduce the soil bulk density. The function time of inorganic soil amendments on soil bulk density was longer than others and can keep relative low bulk density in the latter stage of the experiment. The saturated soil water content had a negative correlation with the soil bulk density.(3) The long cut straws decreased soil water infiltration rate apparently. The finely cut and aminated straws was better than that of control and the finely cut straws at raising stable infiltration rate and cumulative infiltration. The inorganic soil amendment could considerably increase stable infiltration rate and cumulative infiltration.(4) The straws (both finely cut or aminated) enhanced the soil water retention while the finely cut and aminated straws was more effective than the straws finely cut only. The inorganic soil amendment also improved the soil water-holding capacity but has little interaction with straws when they were both applied in soil.(5) The dehydration rate of the soil in the early stage of drought in low suction range increased when the straws (both finely cut or long cut) were applied in soil, while decreased with the aminated straws or straws mixed with inorganic soil amendment, and more soil available water conserved.(6) The finely cut straws or straws(both finely cut and aminated) added into soil could observably increase the amount of >0.25 mm water stable aggregate. At the same time, wheat straw added into soil made fractal dimension of soil pore smaller than the control, then the evaporation rate was increased. Inorganic soil amendment could amend the soil pore distribution and restrain the soil water evaporation. So it can benefit more for the usage of rainwater resource if the finely cut and aminated straw was used with inorganic soil amendment.