| The main type of cultivated land is dam land, flood land, platform land and new cultivated land, it is the very important for the local life. At the same time, The grassland is very important significance for the soil and water conservation of the loess plateau and improvement of ecological environment. The research object is the characteristics of soil and soil quality of grassland, dam land, new cultivated land, platform and flood land. Took the the research plan of design, field investigation, samples collection, determining weights, combining analysis of variance, hierarchical regression analyses, analytic hierarchy process and the principles of fuzzy mathematics and systemic studies the theories of soil quality of five kinds of change main types. The conclusions as follows were reached:1.The five kinds of land use types have bulk densities ranging from0.76to0.92gcc, The soil bulk density increase and porosity of soil reduce with the depth increase;2.Coarse silt content is the most and clay is the least in Soil mechanical composition.Soil particle composition of five kinds of land use types could not be clearly classified for the little difference.Moreover, total description is made as follows (0-100cm except flood land):soil mechanical composition distribution in the grassland is silt (60.97%)>sand (18.76%)>clay (16.39%); soil mechanical composition distribution in the dam land is silt (59.27%)>sand (28.24%)>clay (11.91%); soil mechanical composition distribution in the flood land is silt (50.75%)>sand (40.19%)>clay (9.07%); soil mechanical composition distribution in the platform land is silt (59.33%)>sand (27.12%)>clay (13.54%); soil mechanical composition distribution in the new cultivated land is silt (53.87%)>sand (37.46%)>clay (8.68%)3. The soil moisture content of the five kinds of land use types increase with the depth increase. The soil moisture content also has the lowest ranging from0-20cm to20-40cm.Itshould stabilise under40cm.The platform land have soil moisture content ranging from10.12%to6.30%, The soil moisture content of the dam land would fluctuate in wide range but new cultivated land and grass land is little blips.4.The average amount of organic matter of kinds of land use types were as follows:the platform land (10.33g/kg)>the flood land (9.11g/kg)>the grassland (8.40g/kg)>the dam land (8.25g/kg)> the new cultivated land (7.83g/kg).The organic matter content of surface soil from0to20cm was significantly higher than the other levels, with the increasing depth, organic matter content have different slightly reduced the soil organic matter content of the grass land are lower than average the platform land and the flood land.5. Total nitrogen of the new cultivated land are lower than other land use types, its"lower"level. The available N of kinds of land use types is different.The platform land (16.80mg/kg)>the grassland (15.42mg/kg)>the dam land (15.33mg/kg)> the new cultivated land (15.25mg/kg)>the flood land (15.18mg/kg). It have the basic tendency with the content of total nitrogen. The total nitrogen of kinds of land use types is different, the platform land (0.85g/kg)>the flood land (0.72g/kg)>the grassland (0.71g/kg)>the dam land (0.70g/kg)>the dam land (0.65g/kg).Overall, total nitrogen content of the soil is low.6.The amounts of soil total phosphorus and the total K of the study area are far more stable, its"sub-high" level, top layer were greater than that in lower layer. The amounts of soil available phosphorous of the study area are"low"level. The available potassium of kinds of land use types is different, the content of differences is obvious in different soil depth, it is far more stable in lower layer.7. According to Shaanxi content of soil organic matter level division standard5different land use types of land according to Shaanxi content of soil organic matter grade standards, Northern Shaanxi hilly-gully region five land types with seven level of organic matter content is given priority to, eight level and six level for secondary. The major level of soil total nitrogen content is sixth, only level of soil total nitrogen content of the platform is sixth. The level of all soil rapidly available N is eighth. The level of soil phosphorus is fifth. The most of soil available P level is low of fifth, except of fifth and fourth level of platform and flood land. The total K level of six different types of land use is third. The available K level of five different types of land use is first, except of new cultivated land and dam land, and the order of integrated soil fertility quality was:dam land<new cultivated land<grassland<platform<flood land. |
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