| The production of rice paddy crops plays an important role in China's agriculture and national economic development.However,most of China's rice-field production areas are unilaterally pursuing high-yield and inappropriate fertilization management,which has led to an increase in the application of chemical fertilizers,and has also triggered a series of environmental pollution problems while production increasing.Follow the zero-growth action of the Ministry of Agriculture,we find a scientific fertilization program that can ensure crop yield while reducing environmental emissions,which is significant for the sustainable development of agriculture.In this study,the rice field crops in Ezhou City.Hubei Province were used as the research object.The statistical analysis and environmental risk assessment of rice field fertilization under the typical rice-rice and oil-rice planting patterns were carried out.The environmental discharge of rice fields was measured by DNDC model.Based on this,a l ife cycle assessment system was constructed,and the resource consumption and environmental discharge under different rice crops and different rotation systems were finally determined.Finally,a fertilization scheme was established to simulate food and to reduce environmental pollution.The conclusion is as below:1.According to the planting area,the fertilization amount of rapeseed,early rice,mid-season rice and late rice in Ezhou City were 252.15 kg/hm2,266.93 kg/hm2,293.03 kg/hm2,and 3 15.53 kg/hm2,respectively,which exceeded the application standard of chemical fertilizer application of 250 kg/hm2 in ecological county.The environmental risk levels of total fertilizer pollution in early rice,mid-season and late rice were mostly in low-risk state expect for rapeseed,indicating that there was a certain degree of excessive fertilization in Ezhou.2.In terms of environmental emissions of rice paddy crops,the CH4 emission of rapeseed is significantly different from that of rice,with an average of-1.21 kg/hm2,which belongs to carbon sink,while the CH4 emission of rice is above 60 kg/hm2;The average N2O emission of rapeseed is 1.78kg/hm2,which is higher than that of rice;The average NHs emission of rapeseed is 38.38 kg/hm2.which is lower than that of rice;As for nitrogen loss,the nitrogen loss of rapeseed and rice are above 1 OkgN/hm2.3.The comprehensive environmental impact index of producing 1t rapeseed grain is higher than that of producing 1t rice grain,and the comprehensive environmental impact index of producing lhm2 oil-rice rotation system is smaller than that of rice-rice rotation system.The most influential types of rice field crop fertilization environment are eutrophication and environmental acidification,in which the contribution of eutrophication accounts for more than 80%,while the most contributing to eutrophication is NO3-leaching and NH3 volatilization,indicating that the comprehensive environmental impact index is reduced.The key is to reduce NH3 volatilization and NO3-loss.4.After the fertilization amount gradient simulation of rice fields in Ezhou City,two fertilization schemes of;"production balance fertilization point" and "ertilization amount threshold" were obtained.The former can ensure that the yield of paddy crops in Ezhou reaches the maximum in 2010-2030.However,the environmental emissions are the most serious;the latter can ensure that the crop yield will maintain the average of 2007-2009,and the amount of fertilizer will be reduced relative to the baseline value,and the environmental cost will be the least.The basic fertilization program combined with soil testing and formula fertilization technology was promoted in various townships and towns in Ezhou.Besides,the deep application of chemical fertilizer can increase crop yield while reducing nitrogen loss.Organic fertilizer combined with chemical fertilizer can also reduce the nitrogen loss of fertilizer by replacing some fertilizers. |
PDF Full Text Request