Temporal and spatial change of cultivated land use intensity in China based on emergy theory.

Limited cultivated land has become one of the major restrictions for China's social and economic development, and how to use it intensively is the focus of the Chinese government and research scholars. Based on emergy theory and methods, the cultivated land use intensity (I) was composed of production factors intensity (P) and multiples the multiple cropping index (M). On this basis, the paper analyzed the temporal and spatial change law of all the five production factor intensities, which are farm machinery, fertilizer, pesticide, agricultural film and labor, and the multiple cropping index in China from 1990 to 2011. The results showed: Firstly, during the past 22 years, the farm machinery intensity, fertilizer intensity, pesticide intensity, and agricultural film intensity were all in a linear growth trend, and their annual growth rates were 6.59%, 2.89%, 3.88% and 7.42% respectively; while the labor intensity was in a linear decreasing trend, and its decreasing rate was 5.10 percent. In 1996, the possession of industrial supplementary energy intensity, including farm machinery, fertilizer, pesticide, and agricultural film, in the total production factors intensity first exceeded 50 percent, which meant that China had entered the modern agriculture stage in the middle of 1990s. During the study period, multiple cropping index was also in a linear growth, and the annual growth rate is 0.79%; its total increasing rate was 0.1794 in the past 22 years, and was the major driving force of the increase of land use intensity. Secondly, in 1996, the provinces with high labor intensity and low development of modern agriculture were mainly located in the western part of China, and the typical characteristics of these provinces were that they were all rated with a relatively low level of social and economic development; While in the provinces with high development of economic levels and a good industrial foundation, the labor intensity was low and development of modern agriculture was high. From 1996 to 2008, most provinces in the western part of China and some of the coastal provinces in the eastern part of China, labor intensity decreased a lot; while in the provinces with high economic development and the provinces with more land and fewer persons, labor intensity decreased only a little. In the provinces with high economic development in the eastern coastal part of China and some major grain producing areas, industrial supplementary energy intensity increased a lot; In the provinces with high development of modern agriculture, industrial supplementary energy intensity increased only a little. Thirdly, from 1996 to 2008, in the major rice producing areas in southern part of China, the multiple cropping index decreased a lot, which was the major reason that contributed to the decreasing of their land use intensity; In most provinces in the northern part of China, the multiple cropping index increased a lot, which was the major reason that improved their land use intensity. [ABSTRACT FROM AUTHOR]