Study On Soil Properties Of Erosion Bandland In Loess Hilly Region

Through field investigations, laboratory analysis and statistical analysis, we comprehensively studied the soil physical properties, chemical properties and enzyme activity of high wood land, shrub land, grassland and farmland four land use types at eroded land in Loess Hilly Region. The results show that:(1)The effects of different land use types on soil bulk density is different, the improvement effects of soil structure of high wood and shrub is better than grassland and farmland, soil bulk density wan tend to decrease; the soil bulk density of high wood land is the smallest, the shrubbery followed, farmland is the biggest.(2)The soil moisture content of all four land use types are reduce by the increase of soil depth, the high wood land has the best water-holding capacity, the soil moisture content is the highest in high wood land whether in the whole soil profile or in every layers of the soil profile, the shrubbery followed, farmland is the worst.(3)The soil mechanical composition is mainly composed of silt particle in this area, the soil silt content hasn’t significant differences between whether all four land use types or each soil layer of the same land use type; the soil clay content of all four land use types are reduced by the increase of soil depth, the high wood land soil has the highest clay content to the whole soil profile, the shrubbery followed, farmland is the lowest; the soil sand content is in contrast with the clay.(4)Soil organic matter, soil nitrogen and soil phosphorus are all reduce by the increase of soil depth in all four land use types, and they are all dropping fast in 0~60cm soil layer, the content of soil potassium is not significant different between each soil layer; the soil nutrient content is different in different land use types, the organic matter, nitrogen, phosphorus and total potassium of high wood land are higher than other three land use types, the available potassium of farmland’s surface layer is the highest due to the effect of fertilizers; the order of four land use type comprehensive fertility is high wood land > shrub land > grassland > farmland.(5)The soil enzyme activity are significant differences between different land use types(at 95% level), four kind soil enzyme activity of high wood land are all in the highest level, the shrubbery followed, farmland is the lowest; the results show than the soil enzyme activity of soil surface layer have close interrelations.(6)There are close correlation between soil physical and chemical properties apart from soil silt particle; there are close correlation between four kind enzyme activity and soil nutrition indexes in soil surface layer too, most soil nutrition indexes significant positive correlation or very significantly correlated with four kind soil enzyme activity, but available potassium shows different degree negative correlation with four kind soil enzyme activity.