Changes in quantity and quality of cropland and the implications for grain production in the Huang-Huai-Hai Plain of China

Understanding land use changes and their implications for grain production are important for the maintenance of food security. We analyzed changes in quantity and quality of cropland in the Huang-Huai-Hai Plain of China during the last 30 years and the implications for future grain production. Several categories of data were used, including long-term remote sensing images (1990-2005), spatial datasets of soil quality levels (1980s), spatial datasets of irrigation area (2000), data from hydrological stations (1978-2003) and meteorological stations (1950-2007) and statistical datasets of grain production, grain yield, area sown to grain, fertilizer use and effective irrigation area (1978-2008). The results showed that annual grain production losses due to shrinkage of cropland area over the Huang-Huai-Hai Plain were 4.30 and 2.63 million tons during 1990-2000 and 2000-2005, respectively. The greatest decline in cropland area occurred as a result of the expansion of economically developed metropolises or in provinces with large areas of urbanization. Furthermore, more above average quality and irrigated cropland was abandoned, i.e. sacrificed to urbanization or other non-agricultural uses, than that obtained by reclamation. Conversion of fertile and irrigated land to non-agricultural uses due to rapid urbanization appears to be a potential threat to the food security of the Huang-Huai-Hai Plain - even the whole of China. Most of the increase of grain production in the Plain can be attributed to increase in yield per hectare, which was due to improvement of crop varieties, a similar to 400 % increase in fertilizer use and a similar to 20 % increase in effective irrigation area. Policies to optimize utilization of land resources to ensure the soil fertility of cropland and to maximize nitrogen and water use efficiency are required to sustain current grain production and to achieve further increases.