| China is the origin country of peach(Prunus persica,L.)and the largest peach producing country in the world.At present,the total cultivated area and yield of peach trees show a steady increasing trend.Fertilization plays an important role in improving the yield and quality of peach,but in the process of fertilizer production,transportation and field application,greenhouse gas emissions,eutrophication,environmental acidification and other environmental problems will be brought In recent years,the amount of nutrient input in peach orchard in China is higher than that needed by peach trees to maintain normal yield.However,there are few studies on the potential environmental effects brought by this,and insufficient knowledge hinders the optimal management of nutrients in peach orchard.Therefore,it is urgent to find out the status quo of nutrient resources input in typical peach producing areas in China and quantify the major environmental effects and contribution rates in the production process,so as to provide theoretical basis for optimizing nutrient management in peach orchard.Therefore,this research firstly carried out the peasant household survey in the main peach producing areas(north China,northwest and southwest;NC,NW and SW)and quantify the environment impacts(greenhouse gas emissions,environment acidification and eutrophication)by the method of life cycle assessment(LCA)in order to understand the current status of nutrient inputs and main environmental effects of peach orchards in China.Then,optimization research was carried out which based on the primary environmental effect factor(excessive inputs of nitrogen fertilizer)and take the north China production area as the research object.On the one hand,basic soil fertility of peach orchard was studied to quantify the contribution rate of fertilization and basic soil fertility in peach orchard to yield,On the other hand,field experiments with different nitrogen input levels according to the current recommended amount of fertilizer applied and the experiment of replacing50%chemical fertilizer with organic fertilizer were carried out in peach orchards to study the effects of nitrogen optimization on yield and quality of peach trees.The main research results are as follows:The main producing areas of peach in China are generally over-fertilized with high environmental cost and large optimization space.The yield per unit area of peach orchard in China is relatively low,with the highest in the NW,followed by the NC and the lowest in the SW,respectively 37.8,35.7 and31.4 t/ha,and there is no significant difference between regions.The input amount of nitrogen,phosphorus and potassium in NC,NW and SW were 926,499 and 731 kg/ha,559,355 and 712 kg/ha,and 373,215 and 270 kg/ha,respectively.The proportions of organic nutrients in three areas were highest in SW,followed by NC and NW and organic nitrogen,phosphorus and potassium nutrients accounted for 19.7%,17.7%and 20.4%;14.3%,10.9%and 12.6%;8.60%,10.4%and 6.2%,respectively.The reduced potential of environmental effect of peach orchards in China is higher.Compared with high yield and high efficiency orchards(HH),the potential of environmental impact emission reduction is the highest in NC,followed by NW,and the lowest in SW.The optimizing space of NC is 40.0%to 43.3%per unit area,and 56.4%to 57.4%per unit output;the optimizing space of NW is 27.0%to 32.5%per unit area,and 29.2%to 35.3%per unit output;the optimizing space of SW is 14.9%to 17.9%per unit area,and 44.3%to 47.0%per unit output.Based on the current recommended nutrients by experts in peach orchard and the results of previous studies,the reduced inputs of fertilizer in main production areas was estimated,which is largest in NC,followed by NW and SW.Therefore,optimizing nitrogen input is the primary measure to reduce the environmental effect in three producing areas of peach.The results of soil fertility research showed that the contribution of applying fertilizers in peach orchards is low in these three provinces,which is highest in Hebei,followed by Shanxi and Shandong,respectively 27.6%,16.8%and 8.6%.The contribution rate of nitrogen(N),phosphorus(P)and potassium(K)fertilizer to the yield from the largest to the smallest is:K>N>P,respectively is 15.3%,14.5%and 12.2%;Compared with CK,OPT increased the nitrogen content of mature fruits in all peach orchards,while the deficiency of phosphorus and potassium had no significant effect on the nutrient content of mature fruits in the same year.Conventional fertilization can significantly reduce the titratable acid,sugar and increase the content of V_C and the hardness of ripe fruit.With the increase of nitrogen application amount,the yield showed a trend of increasing first and then decreasing when the nitrogen application amount was among 0-473 kg/ha and the yield was highest when nitrogen fertilizer was 315 kg/ha,which was significant in 2018 and 70.6%higher than that of N0 treatment.Compared with other nitrogen application amounts,fruit titratable acid content was the lowest when nitrogen application amount was 315 kg/ha,while fruit weight,fruit hardness,reducing sugar content,V_C content and soluble solid content were all increased,and the sugar-acid ratio reached 33.2(2017)and 38.1(2018),which was the best comprehensive quality.Compared with CK and FP treatments,the replacement of organic fertilizer treatment increased the yield of peach orchard,which were 46.1 and 42.1 t/ha in 2017 and 2018,respectively,and also improved the fruit quality.Overall,environmental risks are caused by excessive input of fertilizer,especially N fertilizer.Field trials preliminarily confirms that soil fertility makes major contributions to yield,which is greater than the fertilizer inputs.Optimizing by N fertilizer and organic replacement can greatly reduce the amount of chemical fertilizer and improve the peach industry to realize high-efficiency and green development. |
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