The Method On The Information Extraction Of Winter Fallow Fields In Middle And Lower Reaches Of The Yangtze River By The Time Series Ndvi

China has the largest population and the least per capita arable land in the world. With China’s rapid development of economic, industrialization and urbanization, the country’s arable land resources showing a trend that the number and quality became more less and worse. It is a serious impact on national food security, ecological environment security and social stability. In the last20years, more and more farmers to give up the autumn cultivation because of the rapid development of economic, industrialization and urbanization. It leads to that more and more farmland be idled by farmers between the autumn harvest and the plant on next year. The fallow fields even over50percent of the arable land in some areas. Food and energy security is always a top priority to maintaining social stability in china. A large number of fallow fields brought great risks to our food security. It also reduce the farmers’ income. Now, with the promotion and application of efficient agriculture and new rural policy, government attaches great importance to the efficient use of the Fallow fields. Enhance the effective development of winter fallow field use is of great significance for the protection of our food security, particularly for the south china which have the plenty of water and light resources.For efficiently using the winter fallow fields, we must know the number and the Geographical distribution of winter fallow fields. However, the fallow field data do not meet the demand of work and study, regardless of quantity and accuracy. So we need using remote sensing data to extracting the information of winter fallow fields readily and practically. But the remote sensing monitoring is used for the estimates of cropland area and grain yield estimation. We have no way to extracted the winter fallow fields in Large-scale by remotesensing. For using the fallow fields rational and efficient, we study of the method on the Monitor and extraction of winter fallow fields by the SPOT-VEGETATION NDVI time series data and crop phenology. In the end, we use the method extracted the autumn harvest time and planting time in middle and lower reaches of the Yangtze River from2004to2005and2007to2008, and finally extracted the winter fallow fields by the autumn harvest time and planting time.According to the result, the area of the winter fallow fields in study area is144.1million square kilometers between2004and2005, and In2008, the area of the winter fallow fields in study area Increased to205.5million square kilometers between2004and2005,45.49%of the total cultivated area. It is an increase of43.42%in2008compared to2005. The winter fallow fields gathered in the northeastern, northwest and southwest part of the study area. Jiangxi provinces which in the middle of the study area also have a large number of winter fallow fields. It makes a trend that the area of winter fallow fields is on the rise. Overall, it shows an increase from south to north and east to west trend. Hunan provinces have the largest number of winter fallow fields both in2005and2008. We also found that the idle time of winter fallow fields is increasing from2004to2008.In the study, we found that the high speed development of economy and the new rural economy in the adjustment of industrial structure is the reason for the increasingly area and idle time of the winter fallow fields. For this reason, the rural labor forces go to other place to find work for higher income. It lead to rural do not have enough people to farm in the time which between the autumn harvest and the plant on next year. The farming cost which after the autumn harvest is higher than idle. So the winter fallow fields become more and more in these years. And the climate in southeast of the study area has more rain and sunshine lead the winter fallow fields is less than other place of the study area.