中文摘要：

聚丙烯酰胺（PAM）作为一种良好的土壤改良剂,对土壤结构的改善及其土壤对水分和养分的保持发挥了巨大作用,为了研究PAM对紫色土物理性质及其空间变异的影响,进行了野外径流小区试验,试验采用PAM的4种施用模式,包括A模式（浓度为30g/m3PAM液施）、B模式（浓度为60g/m3PAM液施）、C模式（浓度为30g/m3PAM液施结合添加剂）、D模式（浓度为60g/m3PAM液施结合添加剂）,并对紫色土坡面及其不同坡位的土壤水稳性团聚体、机械组成、容重、初始含水率以及土壤渗透率进行了测定,结果表明,C模式对促进〉0.25mm水稳性土壤团聚体形成最明显,增大了23.87%,而相同模式下的不同坡位〉0.25mm水稳性团聚体含量的增量排序均为：上坡〉中坡〉下坡;4种模式在坡面及其不同坡位都促进了土壤中砂粒、粘粒的增加和粉粒和土壤容重的减少,其促进作用为：C模式〉B模式〉A模式〉D模式;在坡面位置C模式分别提高初渗速率和稳渗速率1.790mm/min和0.701mm/min,同一模式下,土壤稳渗率的增量表现为：上坡〉中坡〉下坡。因此适当浓度的PAM结合添加剂的方式对紫色土物理性质的改良效果最好。

英文摘要：

As soil conditioner,Polyacrylamide（PAM） plays an important role on improving the soil water preserving capability and controlling the loss of soil nutrient. The experiment was conducted to determine the effects of four different rates of PAM,which were 30 g/m3（A model）,60 g/m3（B model）,30 g/m3 combining additive agent（C model）,60 g/m3combining additive agent（D model）,on the physical properties and spatial variability of purple soil,and measures the water stable aggregate,soil mechanical composition,soil bulk density,moisture content,infiltration rates of different positions in the soil slop. The results shows that： comparing with the no PAM application slope,the 〉0.25 mm water stable aggregate increases on 23.8% by using the application of C model,under the conditions of same application PAM and different slope positions ,the increasing of the water stable aggregate was most in the up-slope,and less in the down-slope;All of the four models increases on the amounts of sand and clay but decreases on the amounts of silt and soil bulk density;Comparing with the no PAM application slope,the initial rate of infiltration and stable rate of infiltration were accordingly increased 1.790 mm/min and 0.701 mm/min by using C model application. Under the condition of same application model,the up-slope＇s increment of stable rate of infiltration is most. So the effect of PAM application and additive agent on improving the physical properties of purple soil is best.