The Effect Of Straw Mulch And PAM To Red Soil On The Soil-atmosphere Interface

Slope is the important agriculture resource in red soil regions,but the utilization of the resource is restricted severely by the seasonal drought in summer and water erosion in spring.In this paper,by using soil column experiment in the lab and field experiment in the bare land,we researched the effect of addition of straw mulch and PAM to soil on soil water transmission on the soil/atmosphere interface.Moreover,we further investigated the influence of these treatments on soil water evaporation and infiltration and seek for the optimal method to regulate the soil water transmission on the soil/atmosphere interface.These research results are as followed:1.That addition of straw mulch and PAM to soil could effectively change soil water characteristics.Saturated hydraulic conductivity and the ability of water conservation were increased significantly by using the two treatments.The higher values soil water suction were,the more obvious discrepancy of soil water between straw mulch and PAM and the comparison could be got.Soil water content on soil derived from the quaternary red clay was higher than that of soil formed from quartz sandstone matrix. At every soil layer,soil saturated hydraulic conductivity from the treatment with quartz sandstone matrix was obvious higher than that of the Quaternary red clay.2.That addition of straw mulch and PAM to soil could also effectively changed soil water infiltration.By using straw mulch,the infiltration rate is always stable and high at the entire infiltration stage;after the use of PAM,the infiltration rate was most high, and then decreased quickly.The stable infiltration rate with the straw mulch treatment was the same as that with PAM treatment.Under different soil water content,both of the straw mulch and PAM treatments could increase soil water infiltration.But compared with PAM treatment,the straw mulch was more effective to increase soil water when soil water content was low;however,the increase ability was weak when soil water was high.Compared with the use of quartz sandstone matrix,29%and 19% higher accumulative infiltration rate could be achieved with the two different treatments when using quaternary red clay matrix,respectively.3.The straw mulch and the PAM treatments could inhibit soil water evaporation.The inhabitation effect by the straw mulch was more obvious,especially in the first stage. PAM treatment could increase obviously soil water content before water evaporation, while the affect of the treatment on stopping soil water loss was not obvious.Under different soil water content,the law of the two treatments to decrease soil water evaporation was the basic same.The straw mulch and the PAM treatments used in quaternary red clay matrix could more effective than the two treatments used in the inquartz sandstone matrix to reduce soil water evaporation4.The straw mulch and the PAM treatments could reduce runoffs and increase infiltration.In the each plot,the average rainfalls come from 8 times precipitation were as follows:the comparison with quaternary red clay matrix(2.95 mm)＞the straw mulch treatment(2.15mm)＞the PAM treatment(2.05mm);the comparison with inquartz sandstone matrix(2.84 mm)＞the straw mulch treatment(2.15 mm)＞the PAM treatment(2.05mm).When soil water content was very high,the straw mulch treatment and the PAM treatment could still promote infiltration of rainwater into soil.