This study investigated the adverse effect of surface ozone on the maize yield using a unique panel from 880 counties in China.To identify the impact of elevated surface ozone concentrations,we constructed an economet...This study investigated the adverse effect of surface ozone on the maize yield using a unique panel from 880 counties in China.To identify the impact of elevated surface ozone concentrations,we constructed an econometric model by controlling the impact of climate variables and related economic variables.This study also considered the potential spatial correlation in the measurement of the impact of surface ozone on maize yield.Results confirmed that the increase of ozone concentration decreased the maize yield.Moreover,maize was found to be the most sensitive to ozone at the end of the second month of the growing season.The average annual loss of maize caused by ozone pollution is about 4.234 million tons in 2013–2015,accounting for 1.9%of the average output.展开更多
Globally climate change has threatened agriculture and food security which is of great importance to the economy of a nation. In Nigeria it has become a great concern to the government and people because of the obviou...Globally climate change has threatened agriculture and food security which is of great importance to the economy of a nation. In Nigeria it has become a great concern to the government and people because of the obvious changes in the climate systems, therefore, assessing the impact of climate change on crop yield in an oil producing state is of great importance especially where rain fed agriculture is the main determinant for crop yield. Expost-facto research method in the context of quasi experimental research design was adopted for the study. Data for rainfall and temperature and that for crop yields were obtained from Nigerian Meteorological Agency (NIMET) and federal ministry of Agriculture;Agricultural Development Program (ADP) respectively. Analysis of data was achieved using descriptive statistics, trend graphs and multiple linear regressions. Results showed that there had been a steady but gradual increase in the annual minimum, maximum and mean temperatures over the study period of thirty years and a decrease in rainfall. Mean temperature is increasing annually at the rate of 0.0253 per annum and rainfall is decreasing at the rate of -0.5817 mm per annum. The multiple regression model showed r2 values of 0.28 for maize and 0.29 for cassava revealing that only 28% - 29% of maize and cassava yields could be explained by rainfall and temperature in the state and the result was significant at p < 0.05 revealing that cassava and maize yields significantly depended on rainfall and temperature. This study strongly advocates for a better and practicable environmental policies and improved agricultural techniques alternative source of water which will include irrigation farming, mulching since it is evident that there is a reduction in rainfall and increase in temperature in the state while creating sustainable food security.展开更多
The increased population density, coupled with changes in dietary habits in developing countries towards high quality food and the increasing use of grains for livestock feed is projected to increase demand for food p...The increased population density, coupled with changes in dietary habits in developing countries towards high quality food and the increasing use of grains for livestock feed is projected to increase demand for food production by 70% by 2050. Crop yields would continue to grow but at a slower rate than in the past. Yield growth will play an important role as only a slow expansion of agricultural land is expected. Future yield increases on lands currently supporting high production levels must come from continued yield enhancing genetic modifications. The most important grain and feed is maize. Genetic improvement has not only contributed to yield increases but also to other desirable plant components such as resistance to lodging and tolerance to increased plant populations, insects, and diseases. Maize production has increased from 200 million tons in 1960 to over 800 million tons in 2011 but has not changed very much recently. The reviews suggest that the overall assessment of farm-level costs and benefits of GM maize has severe limitations. Nonetheless, GM maize is a potential tool to increase farmers’ income and thus might contribute to poverty reduction and sustainable social and rural economic development, especially in developing countries. The results support the contention that the adoption of GM maize leads on average to a higher economic performance, i.e., benefits, for farmers than conventional (non-GM) crops. An important finding of the analysis is that the kind and magnitude of benefits are heterogeneous across crops, traits, countries and regions. However, while the literature on the economic impact of GM crops has grown in recent years there is still a need for more comparative studies across space and time in order to pin down these impacts and allow for a better assessment of the contribution that this technology can make to sustainable development.展开更多
基金the financial support by the National Natural Science Foundation of China (71673137)the Nanjing Agricultural University, China (Y0201400037, SKCX2015004)+4 种基金the Education Department of Jiangsu Province, China (2014SJD069)the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD)the China Center for Food Security Studies at Nanjing Agricultural UniversityJiangsu Rural Development and Land Policy Research InstituteJiangsu Agriculture Modernization Decision Consulting Center, China
文摘This study investigated the adverse effect of surface ozone on the maize yield using a unique panel from 880 counties in China.To identify the impact of elevated surface ozone concentrations,we constructed an econometric model by controlling the impact of climate variables and related economic variables.This study also considered the potential spatial correlation in the measurement of the impact of surface ozone on maize yield.Results confirmed that the increase of ozone concentration decreased the maize yield.Moreover,maize was found to be the most sensitive to ozone at the end of the second month of the growing season.The average annual loss of maize caused by ozone pollution is about 4.234 million tons in 2013–2015,accounting for 1.9%of the average output.
文摘Globally climate change has threatened agriculture and food security which is of great importance to the economy of a nation. In Nigeria it has become a great concern to the government and people because of the obvious changes in the climate systems, therefore, assessing the impact of climate change on crop yield in an oil producing state is of great importance especially where rain fed agriculture is the main determinant for crop yield. Expost-facto research method in the context of quasi experimental research design was adopted for the study. Data for rainfall and temperature and that for crop yields were obtained from Nigerian Meteorological Agency (NIMET) and federal ministry of Agriculture;Agricultural Development Program (ADP) respectively. Analysis of data was achieved using descriptive statistics, trend graphs and multiple linear regressions. Results showed that there had been a steady but gradual increase in the annual minimum, maximum and mean temperatures over the study period of thirty years and a decrease in rainfall. Mean temperature is increasing annually at the rate of 0.0253 per annum and rainfall is decreasing at the rate of -0.5817 mm per annum. The multiple regression model showed r2 values of 0.28 for maize and 0.29 for cassava revealing that only 28% - 29% of maize and cassava yields could be explained by rainfall and temperature in the state and the result was significant at p < 0.05 revealing that cassava and maize yields significantly depended on rainfall and temperature. This study strongly advocates for a better and practicable environmental policies and improved agricultural techniques alternative source of water which will include irrigation farming, mulching since it is evident that there is a reduction in rainfall and increase in temperature in the state while creating sustainable food security.
文摘The increased population density, coupled with changes in dietary habits in developing countries towards high quality food and the increasing use of grains for livestock feed is projected to increase demand for food production by 70% by 2050. Crop yields would continue to grow but at a slower rate than in the past. Yield growth will play an important role as only a slow expansion of agricultural land is expected. Future yield increases on lands currently supporting high production levels must come from continued yield enhancing genetic modifications. The most important grain and feed is maize. Genetic improvement has not only contributed to yield increases but also to other desirable plant components such as resistance to lodging and tolerance to increased plant populations, insects, and diseases. Maize production has increased from 200 million tons in 1960 to over 800 million tons in 2011 but has not changed very much recently. The reviews suggest that the overall assessment of farm-level costs and benefits of GM maize has severe limitations. Nonetheless, GM maize is a potential tool to increase farmers’ income and thus might contribute to poverty reduction and sustainable social and rural economic development, especially in developing countries. The results support the contention that the adoption of GM maize leads on average to a higher economic performance, i.e., benefits, for farmers than conventional (non-GM) crops. An important finding of the analysis is that the kind and magnitude of benefits are heterogeneous across crops, traits, countries and regions. However, while the literature on the economic impact of GM crops has grown in recent years there is still a need for more comparative studies across space and time in order to pin down these impacts and allow for a better assessment of the contribution that this technology can make to sustainable development.
