Comparative Environmental Impact Study Of Conventional And Organic Rice Cultivation System Based On LCA

Under the double pressures of population increase and cultivated land drop,increasing rice yield has become one of the important methods to ensure food security in China.In the case of high-input and high-output intensive production,every year a large number of arable lands,energy,irrigation water and agricultural chemicals are put into all aspects of rice cultivation.Once the management is defective,these resources and energy Consumption at the same time will be accompanied by environmental hazards.How to make an objective analysis and response to the environmental impact of rice planting system has a long way to go.With the method of life cycle assessment,the paper takes Bayan County,Heilongjiang Province as the case to analyze the resources' consumption and pollutant releasing of conventional and organic rice cultivation system in northeast China.On the basis of that,the comparative environmental assessment was accomplished.The results of LCI showed that there is little difference in the consumption of organic rice and conventional rice cropping systems,where the former consumes more hard coal,which is 1.78 times higher for the latter.In addition,the resource consumption is slightly lower than the conventional rice,the total consumption is 0.81 times the latter.In the aspect of pollution release,organic rice cultivation system had six indexes higher than that of conventional rice,namely NMVOC,NH₃,CH₄,BOD,COD and ammonia nitrogen.The same amount of release was 1.81 times,1.04 times,2.13 times,1.96 times,1.80 times and 1.99 times.For other pollutant indicators,conventional rice cultivation emissions are higher than organic rice.The results of LCIA showed that the significant environmental impact factors are global warming potential,acidification potential,eutrophication potential and fresh water eco-toxicity potential.The environmental impact index of conventional rice is 5.24 in comparison with 4.15 for organic rice.If conventional rice were widely replaced by organic rice,acidification,eutrophication,human toxicity and fresh water eco-toxicity potential would be reduced by 47%,32%,85% and 67%.However,global warming and fossil energy consumption potential would increase 65% and 14%.In terms of environmental impact,organic rice is not totally superior to conventional rice.In the system of conventional rice cultivation,the agricultural materials period contributes most to environmental impact,occupying more than 60% in eutrophication,fresh water eco-toxicity,terra firma eco-toxicity,human toxicity,acidification and fossil energy consumption potential.In the system of organic rice cultivation,growing period contributes most to environmental impact,taking the place of the agricultural materials period.In order to reduce the impact of rice cultivation on the environment,it is possible to consider improving the two aspects from optimizing the field operation and the clean production of the chemical fertilizer industry.By alternately irrigating dry and wetting,increasing the soil permeability and developing the soil fertilization formula can significantly reduce N₂O and rice fields CH₄ emissions,thus weakening the contribution to global warming;through the water and cold round as a continuous rice model and optimize the amount of fertilizer,can effectively control the rice field acidification;no-tillage,delayed tillage time and water-saving irrigation can be cut by nitrogen and phosphorus nutrients Runoff loss to control eutrophication,and drip fertilization can be in the basic crop production under the premise of the more obvious reduction of nitrogen and phosphorus runoff loss.While the fertilizer industry to implement cleaner production,it can greatly reduce the agricultural stage of the environmental impact.