Land Rights,Reform And The Evolution Of China's Soil Resource

As China's increasing population continues to exert pressure on the natural resources and environment in China,issues related to the evolution of soil quality-and in particular soil fertility-have become an increasing focus of worldwide concern. The primary objective of this dissertation is to identify the determinants of changes in soil fertility and quality in China in the period from the early 1980s to 2000. After describing measures for soil fertility and quality,the study examines the possible impact of socio-economic factors on soil fertility and quality,especially land tenure institutions governing tenure security and land transfer rights.The data used in this dissertation originate from 3 regions in China-the Northeast,the North China Plain and the mid-lower Yangtze River-and cover 6 provinces,15 counties,and 180 sample plots. The data include information on soil fertility,quality,and corresponding socio-economic data for the households farming the sample plots. The primary soil fertility indicators analyzed are soil organic matter,total nitrogen,effective phosphorus,and effective potassium. Every soil fertility factor was recorded both in the early 1980s and 2000 at the same sample plot. All socio-economic data were derived from interviews with the production team leaders in charge of the sample plots,and were also gathered in both periods. After describing the trends in changes in soil nutrients from the early 1980s to 2000,the dissertation sets up an econometric model to measure the possible impact of socio-economic factors on soil fertility.On average,soil organic matter,total nitrogen,effective phosphorus content improved,but measures of the effective potassium in the soil,and the pH-value,worsened. From the perspective of spatial distribution,however,there is significant variation in soil fertility and quality. The average soil fertility rose in the North China Plain and Mid-lower Yangtze River regions,and decreased in the Northeast. Additionally,although the North China Plain saw an improvement in soil pH-value,acidification of the soil increased in the other regions.As is well known,soil quality changes over time due to natural processes and the impacts of human activities. However,the impacts of cultivation on soil fertility have been deepening. The previous literature on factors determining soil quality changes mainly focused on the natural processes of soil quality change,while socio-economic and policy factors tend to be neglected. The econometric results in this dissertation show that socio-economic and policy factors indeed have an important influence on soil fertility change. More specifically,the results show that tenure security may improve soil fertility such as organic matter. However,imperfect land transfer rights may damage the sustainable productivity of the soil. Other important results show that whereas income growth among farmers has a positive effect on the organic matter content of the soil,the endowment of cultivated land had a negative effect on nutrients. Other factors that were found to have positive effects on soil nutrients include the multiple cropping index and the practice of plowing stalks back into the land.These findings lead to several policy recommendations. First,it shows that economic variables are very important in determining changes in soil fertility,and therefore the theory and method of economics should be taken seriously by soil scientists. Second,as land rights are found to be an important indicator of fertility improvements,if the land use rights of farmers are improved,they can expect more returns from their land investments,which can lead to soil fertility improvements. Third,complete land transfer rights,which also have an important effect on soil fertility,should be endowed to farmers to encourage them invest on cultivated land promoting the sustainable productivity of the land. Fourth,population growth negatively affects fertility,so controlling population growth can help keep the quantity of tilled land steady,therefore alleviating t...