Effects Of Organic Fertilizer Instead Of Chemical Fertilizer And Regulation Level Of Nitrogen,Phosphorus And Potassium On Apple Production

Apple（Malus pumila Mill.）has become one of the important fruits in the world fruit industry because of its rich nutrition,sweet taste and storage resistance.As the world’s largest producer and consumer of apples,China ranks first in the world in terms of planting area and total production.Shandong Province plays a pivotal role in the country’s apple production by virtue of its superior geographical location and suitable climatic conditions.Although the vigorous development of the fruit tree industry is inseparable from the application of chemical fertilizers,due to the fact that fruit farmers are deeply influenced by traditional fertilization concepts,the ratio of nitrogen,phosphorus and potassium fertilizers in apple planting is not balanced.Fertilization not only hinders the growth of fruit trees,but also has a serious negative impact on soil and atmospheric ecology.Under the background of zero growth of chemical fertilizer application,this study used 7-year-old’Yiyuanhong’apples as materials,and carried out experiments in orchards of reducing the proportion of chemical fertilizers under different levels of organic fertilizers and controlling the total amount of nitrogen,phosphorus and potassium fertilizers under the same level of organic fertilizers.By analyzing the yield,quality,soil nutrient content and biological characteristics of fruit trees,the optimal ratio of organic fertilizer and chemical fertilizer application was explored.In order to provide theoretical and technical support for the rational fertilization of Shandong apple industry.Through two consecutive years of fruit tree planting,the main findings are as follows:（1）The effect of reducing chemical fertilizer application on apple yield,quality and soil biochemical properties under different organic fertilizer levels showed that the order of apple yield under different fertilization treatments was:B（C₂+O₁）>C₃+O₂>A（C₂+O₁）>C₃+O₁>C₂+O₂>C₁+O₁>C₁+O₂>C.Among which the fertilization treatment of organic fertilizer instead of chemical fertilizer increased apple yield by 8.86%～65.26%compared with the conventional fertilization treatment C,and the net income was higher than that of the conventional fertilization treatment significantly increased by 4.47%～60.51%.In 2019～2020,the net income value of B（C₂+O₁）treatment was the highest,reaching 45,685.12 yuan/hm~2,which was a net increase of 17,222.67 yuan/hm~2 compared with conventional fertilization.At the same time,the replacement of chemical fertilizers with organic fertilizers also has a positive effect on the optimization of apple quality and the improvement of available nutrients in the soil.In terms of internal and external quality of apples,according to the comprehensive evaluation of apple quality,yield and other indicators based on principal component analysis,the total score of 500 kg/mu of organic fertilizer instead of 20%chemical fertilizer was the highest,reaching 2.53.Its single fruit weight was reached 311.45 g in 2020,which was 38.89%higher than that of C treatment.The soluble sugar content was 21.10%higher than that of conventional fertilization.In terms of soil physical and chemical properties,the contents of soil organic matter,available potassium and available phosphorus were all increased compared with conventional common fertilization treatments.The p H value of soil in the treatment of organic fertilizers replacing chemical fertilizers changed from weak acidity to neutrality with the increase of fertilization years.The best treatment for soil organic matter content is to replace 20%chemical fertilizer with 300 kg/mu of organic fertilizer.Compared with conventional fertilization,the results were increased by 19.67 mg/kg,13.66 mg/kg and8.45 mg/kg respectively.The soil ammonium nitrate nitrogen content was best treated with500 kg/mu of organic fertilizer instead of 20%chemical fertilizer,the soil layer of 0-20 cm increased by 21.71 mg/kg and 6.31 mg/kg respectively,and the content of available potassium increased by 106.93%.To sum up,the replacement of chemical fertilizers with organic fertilizers increases the yield of fruit trees,improves soil fertility and fruit quality in orchards,and meets the nutrient requirements of fruit trees in different developmental stages.It is recommended that 500 kg/mu of organic fertilizers replace 20%of chemical fertilizers in production.（2）The results of total control of nitrogen,phosphorus and potassium fertilizer under the same organic fertilizer application level showed that the nitrogen,phosphorus and potassium fertilizer optimized formula fertilization（MN₂P₂K₂）treatment had the best apple yield,compared with the MN₀P₂K₂ treatment,MN₂P₀K₂ treatment and MN₂P₂K₀ treatment without nitrogen,phosphorus and potassium fertilizer application.In comparison,the yields increased by 9.59 t/hm~2,8.06 t/hm~2 and 8.11 t/hm~2,respectively.At the same time,after 2 consecutive years of different fertilization treatments,the content of soil available nutrients has been greatly improved.Under the same level of organic fertilizer,in the experiment in which phosphorus and potassium fertilizers were applied according to the optimized formula and the total amount of nitrogen fertilizer was controlled,the change of soil ammonium nitrate nitrogen content in the 0-20 cm soil layer under the MN₂P₂K₂ treatment was the most significant,which was different from the MN₀P₂K₂ treatment without nitrogen fertilizer application.Compared with that,the soil ammonium nitrate nitrogen content increased by20.24 mg/kg and 2.86 mg/kg,respectively.In the total phosphorus fertilizer control experiment,the soil available phosphorus content in the MN₂P₂K₂ treatment increased by 16mg/kg compared with the MN₂P₀K₂ treatment in the phosphorus-free area,and the MN₂P₁K₂treatment in the 70%optimized phosphorus area increased by 54.10%compared with the phosphorus-free area.Based on the yield of fruit trees and the content of available soil nutrients,the optimal formula fertilization treatment with nitrogen,phosphorus and potassium（N 22 kg/mu,P₂O₅ 15 kg/mu,K₂O 22 kg/mu）is the best.