Characteristics Of Nutrients Input And Life Cycle Environmental Impacts In Apple Production System

China is the largest apple producer in the world,the high nutrient input rate and low fertilizer use efficiency in apple orchards not only caused waste of resources,but also brought environmental problems.It was of great significance to the sustainable development of apple production in China by analyzing the nutrients input,environmental impacts,and the approach of environmental emission reduction.Therefore,based on the nutrient inputs survey data of 3535 apple orchards in the main production areas,the nutrient input,structure and suitability of different apple production areas were analyzed in this study.Also,the nitrogen and phosphorus nutrient surplus were calculated using the nutrient balance method.The environmental risk of nitrogen and phosphorus were evaluated based on nutrient surplus and chemical environment safety threshold.Based on the detailed management data of the apple orchard production process and the localization parameters from the literature,the environmental impacts of the apple production system was quantified by the life cycle assessment method.Meanwhile,the reduction potential of the environmental impacts in the apple production system was analyzed by grouping the apple orchards according to their productivity.Then,the environment impacts reduction effect of integrated nutrient management and organic production system were evaluated by the 59 field experiment data in combination with survey data.The main results were as follows:1.In the surveyed apple orchards,the input of chemical fertilizers was high in general and differences between areas were existed.The average inputs of nitrogen,phosphorus and potassium were 1056.12,687.34 and 861.12 kg/ha,respectively.Among them,inorganic nutrients was in dominant.Fertilizer nitrogen,fertilizer phosphorus and fertilizer potassium accounted for 81.02%,79.11%and 81.65%,respectively.Nitrogen and phosphorus nutrient inputs were higher in Shandong and Gansu,lower in Liaoning and Shanxi,while potassium nutrient inputs were higher in Shandong,lower in Shaanxi and Shanxi.Compared with the recommended amount of fertilization,only 17.84%,6.35%and 17.54%of the nitrogen,phosphorus,and potassium nutrients in the orchards surveyed were at the appropriate level,70.24%,88.12%and 56.39%were excess,respectively.The total input of organic fertilizer in the investigated orchard was not high?9.24¹3.01 t/ha?,with an average of 10.82 t/ha.About13.91%of the surveyed orchards did not apply organic fertilizer.2.The high input of nitrogen and phosphorus nutrients in apple orchards lead to high nitrogen and phosphorus surpluses and environmental risks.The average nitrogen surplus of the apple orchards in the survey areas was 296.56 kg/ha which was high environmental risk.Among them,56.85%were in high environmental risk?surplus>200 kg/ha?,while only20.35%were in low environmental risk?<150 kg/ha?.The average phosphorus surplus in the apple orchards was 414.28 kg/ha,of which over 70.20%were more than 200 kg/ha.There was a linear relationship between phosphorus surplus and soil available phosphorus content.The phosphorus surplus in apple orchards in all production areas exceeded the soil phosphorus surplus?190.54³26.28 kg P₂O₅/ha?corresponding to the critical value of soil phosphorus leaching risk?50⁷0 mg/kg?.The average phosphorus surplus was 1.27 times of the upper limit of the critical value of soil phosphorus leaching risk.So,the environmental risk of soil phosphorus leaching in apple orchards was high.The chemical fertilizer environmental risk index was 0.78 on average,and the environmental risk type reached severe risk.Gansu Province had the highest environmental risk index,with an average of 0.81,reaching serious risk level.Liaoning and Shanxi had the lowest environmental risk index,with an average of 0.73 and 0.74,respectively,which was moderate risk level.The type of environmental risks in Shandong,Hebei and Shaanxi were at severe risk level.3.Combining data of survey with literature,and on the basis of localization parameters,the environmental impacts of apple production system was quantified by life cycle assessment?LCA?.The energy consumption,global warming potential,acidification potential and eutrophication potential of apple production system in China were 4597.79 MJ/t,1067.02 kg CO₂-eq/t,5.73 kg SO₂-eq/t and 3.91 kg PO₄-eq/t.There were differences between production areas,the environmental indicators in the Bohai Bay production area were lower than those in Loess Plateau production area.Also,different environmental impacts among farmer groups with different production efficiency were found.Compared with the average potential of environmental impacts of apple production in China,the energy consumption,global warming,acidification and eutrophication potential of the low-yield and low-efficiency group?LL?were1.27,1.32,1.30,and 1.32 times higher than the national average,respectively,while the environmental impacts of the high-yield and high-efficiency group?HH?were 29.18%,34.30%,38.16%and 34.22%lower than the national average,respectively.Thereby,environmental impacts reduction could be effectively achieved by optimizing production management.4.Compared with the farmers'management,the results?59 field trials in 6 years?in the Loess Plateau region showed that the output yield of the nutrient integrated management system?optimizing the fertilization quantity,fertilization type,fertilization period,fertilization method and the ground soil management?increased by 12.77%,the inputs of nitrogen,phosphorus and potassium has been reduced by 28.27%,48.57%and 18.45%,respectively,while the energy consumption,global warming,acidification and eutrophication potential decreased by 25.31%,28.51%,39.36%and 37.78%,respectively.5.Compared with conventional apple production systems,organic production systems showed lower global warming potential,water toxicity,human toxicity and soil toxicity,mainly due to the fact that organic production did not use inorganic fertilizers and chemical pesticides.However,the energy consumption,acidification potential and eutrophication potential of organic production systems were 8.89%,18.74%and 26.91%higher than that of conventional production systems,respectively,which was attributed to the large-scale application of organic fertilizers in organic production and the lower production of organic production systems.In addition,it's important to note that the soil toxicity caused by organic fertilizers in organic production systems was significantly higher than that of conventional production systems.