Spatio-temporal Variability Of Red Soil Fertility And Utilization Potential Evaluation In Low Hill Region Of Longyou County

Based on the data of the second national soil survey and project of low hilly red soil management and development in Zhejiang Province,2005, the soil fertility of low hilly red soil resources and potential for development and utilization of land resources in the study area of Longyou County, Quzhou City, Zhejiang Province were analyzed and evaluated by the method combined geostatistics analysis and soil fertility evaluation. It was important for the rational development and utilization of low hilly red soil resources, and solving the current serious shortage of land resources problem. Combined with spatial and temporal variation of soil fertility research, the results revealed the influence mechanism to soil and land quality by rapid urbanization process and provided the basis for sustainable land management decision-making.The main results, understandings and conclusions of the dissertation were summarized as follows:(1) The results of the study on temporal variation of soil fertility factors in low hilly red soil area, Longyou County, showed:soil organic matter had slight increased, soil available phosphorus and potassium had decreased significantly, and the soil acidity had increased in the past 20 years from 1983 to 2005. Moreover, the overlaid analysis revealed that the changes of soil fertility varied with the land utilization patterns. The organic matter content in red soil increased in the paddy fields and woodland, and no significant change happened in garden land, but decreased in dry land. The soil available phosphorus and potassium decreased significantly in all four types of land use. Soil pH of hilly red soil decreased, however, the landuse ways of garden and woods land had a more marked influence on soil acidity than the dry land and paddy fields.(2) Based on the analytical data of soil samples in 2005, the spatio and temporal variation characteristic of soil fertility factors was studied by using geostatistics tools. Distribution maps of the soil fertility factors were interpolated by ordinary Kriging, which were basic data for soil fertility evaluation of low hilly red soil area.(3) Soil fertility was evaluated using membership function, correlation coefficient method and comprehensive index evaluation model. The results showed: the soil quality was low in Longyou low hilly red soil area, soil available phosphorus and potassium were in a serious shortage, and the soil was too acid. The classⅠtype of soil fertility (very poor) accounted for 7%, classⅡtype of soil fertility (poor) accounted for 32.8%, classⅢtype of soil fertility (medium) accounted for 36.66%, and class IV type of soil fertility (good) accounted for 23.53%. The soil fertility was as followed:the garden land＜dry land＜paddy fields＜woods land.(4) The utilization potential evalutation of the study area was studied by the analytic hierarchy process and comprehensive index evaluation model. It showed that the land suitable for re-development accounted for 16%, and allowed developing accounted for 14%, which mainly distributed on the central plain area of low hilly red soil. The garden and woods land were the main types in the land suitable for re-development and allowed developing, however, the main soil fertility quality were poor or medium. Over all, the future land development work should focused on how to explore the garden and woods land with low productivity, and it was need to raise the soil fertility by fertilizing organic fertilizer, planting green manure, and improving farm management.