A precise spatial knowledge of potential yield and actual yield is crucial to assessing an increase in grain yield and is relevant to national food security. In this paper, the potential maize yields at the county level in 2013 in Northeast China were estimated using a Miami model in combination with an integrated fertility index and the effect of chemical fertilizers on yield increase. Then, the spatial characteristics of the climate, farmland and grain production potential were presented, and the potential yield increase and food security implications were analyzed. The estimated production potentials of the climate, farmland and grain in 2013 were approximately 4.65 x 10(3)-13.06 x 10(3) kg/ha, 2.77 x 10(3)-9.38 x 10(3) kg/ha, and 2.97 x 10(3)-12.1 x 10(3) kg/ha, respectively, whereas the actual maize yield in 2013 was 1.50 x 10(3)-8.60 x 10(3) kg/ha, accounting for 41.86-95.84 % of the grain production potential. The total average potential maize increase in Northeast China was 3.32 x 10(3) kg/ha, measured from the difference between the climate production potential and the actual yield. Furthermore, the main regions with lower surplus production but a higher potential for increase were located in the eastern Liaoning, Jilin and Heilongjiang Provinces. In addition, the surplus production, which was 136.56 million tons, could feed 341.4 million people in other areas of China. In conclusion, we suggest that improving access to agronomic practices (such as fertilizer and high-yielding seed) and developing agricultural policies and strategies could increase the maize yield and further narrow the yield gap.
Three extreme weather scenarios are examined for agriculture in China in this study. One scenario assumes a year when every province has precipitation corresponding to the lowest level experienced in the province over the last three decades. Another scenario assumes the highest experienced precipitation for every province is happening; and the last one assumes that the most harmful level of precipitation on crops occurs for every province - whether too little or too much. We studied the role of autonomous adaptation by farmers and through markets as embodied in a computable general equilibrium model. The results show that observed extreme impacts of precipitation on crop harvests are not serious for China at national level. The maize harvest is the most negatively affected with a reduction of 4 % without adaptation and less than 1 % reduction with adaptation. However, the impacts within a province may be serious and even become worse with adaptation. Good harvests might not make farmers better off due to lower crop prices even though consumers benefit. Sensitivity analysis shows that the ability to adapt assumed in the analysis may not be present in the short term.
The impact of changes in cultivated land on the production potential of food crops in China during the period of 1990-2010 was studied using land use data and the Global Agro-ecological Zones (GAEZ) model. The contribution of crop production potential per unit cultivated land area (PPCLA) to the total food-energy based production potential (TPP) of food crops was further investigated. From 1990 to 2010, China has experienced a net increase of cultivated land, resulting from a net increase in northern China and a smaller net decrease in the south. However, the TPP reduced by 9.64 x 10(12) kcal despite an overall cultivated land increase for crops. This was attributed to the spatial heterogeneity of PPCLA in the cultivated land, whereby the average PPCLA of the newly cultivated land was much lower than that of the lost land. The PPCLA gap between the newly developed land and the lost cultivated land expanded from 3.16 x 10(6) kcal/ha in the first decade (1990-2000) to 6.49 x 10(6) kcal/ha in 2000-2010. Contributions of PPCLA to TPP varied among regions, and the regions with the largest contributions were consistent with those with the largest PPCLA gaps. Such regions included the Sichuan Basin and surrounding region in 1990-2000, and the Huang-Huai-Hai Plain during 2000-2010. Based on these research findings, key implications for land use policies in relation to major food crops in China are discussed.
With the increasing risk of people and economies being subject to meteorological disasters, it is of great importance to analyse the spatio-temporal variation of these disasters. In this paper, the possible impacts of meteorological disasters on rice yields in Jiangsu Province, southeast China was studied. A total of 17 rice meteorological disaster indices (RMDI) during 1961-2012 was calculated and analyzed. The spatial distribution of RMDI indicated that south Jiangsu should be classified as a high-intensity zone for heat stress, while north Jiangsu should be classified as a high-intensity zone for precipitation extremes and chilling injury. Changing trends of RMDI were detected by the Mann-Kendall test. Precipitation extremes and heat stress indices presented increasing trends, while the chilling injury indices showed decreasing trends. Correlation analysis between rice yield and RMDI with the first difference method and climate-induced yield method showed that precipitation extremes had more dramatic negative effects than the other two types of meteorological disaster. Principal components analysis provided additional information about the regional differences of changes in meteorological disasters. Jiangsu could be divided into three regions (south, middle, and north) with different and changing patterns for RMDI. Also the Western Pacific Subtropical High Intensity Index and the Pacific Decadal Oscillation had significant influences on these changes. These findings could provide a scientific basis for the prevention or reduction of rice meteorological disasters in Jiangsu Province.
China's recent rapid economic development has resulted in rampant urbanization and substantial farmland reduction, which makes food security a great policy concern, not only in China, but around the world. The Chinese government has been implementing large-scale land consolidation programs since 1998 in order to stabilize and improve the quantity and quality of national farmland. During 2006-2012, about 6.8% of total national farmland was renewed by land consolidation programs. A comprehensive analysis of the relationship between the spatial distribution of land consolidation projects and the present status (quality and quantity) of respective farmland is critical for the future national land consolidation strategy. Land use, land consolidation management data, implementation status and spatial-temporal features of such implementation were explored. We found that prioritized implementation was weak at the national level; that is, obvious discrepancies exist between implementation intensity and improvement potential of farmland quality. Furthermore, the national land consolidation plan did not provide effective guidance for land consolidation practices; hence policy implementation differs significantly across the country. We suggest that methods of management and operational strategy in land consolidation should be improved.