The Impacts Of Cake Fertilizer Replacing Different Proportions Of Urea On Citrus Yield Quality,Tree Nutrients And Soil Fertility In Citrus Orchard

In recent years,China's citrus industry has developed rapidly,but fruit farmers often over-apply chemical fertilizers for high yields of citrus,which has caused problems such as poor citrus fruit quality,low yield,citrus orchard soil degradation,and agricultural non-point source pollution.Reasonable reduction of chemical fertilizer application is the key to improve the yield and quality of citrus fruit and promote the green and sustainable development of citrus industry in China.Replacing part of chemical fertilizer with organic fertilizer is one of the important ways to reduce the application of chemical fertilizer in citrus orchards.Therefore,in September 2017,this study set up a long-term positioning experiment in the citrus base of Banyue Town,Dangyang city,Hubei Province,selected the easily available rapeseed cake fertilizer as the organic fertilizer source,and explored the effect of different proportion of chemical nitrogen reduction under the application of rapeseed cake fertilizer on the yield and quality of citrus fruit,leaf nutrition,soil nutrients of orange garden and economic benefits of citrus orchards,so as to clarify the chemical nitrogen under the application of cake fertilizer Appropriate proportion of fertilizer reduction.A total of 5 treatments were set in the experiment:(1)CF: local conventional nitrogen application;(2)N0%+C: no nitrogen application + cake fertilizer application(3)N70%+C: 70% of local conventional nitrogen application + cake fertilizer application;(4)N85%+C: 85% of local conventional nitrogen application + with application of cake fertilizer;(5)N100%+C: local conventional nitrogen application + cake fertilizer application.The main results of the two-year trial are as follows:(1)Compared with CF treatment,N70%+C,N85%+C,and N100%+C treatments did not significantly change the citrus production in 2018 and 2019,but the output has increased slightly,and the increase in production is more obvious in 2019.Between 10%-16%.Compared with CF treatment,N0%+C treatment significantly reduced citrus production in 2018 and 2019,especially in 2018,its decline rate reached 24.96%.(2)The individual citrus fruits in each treatment in 2018 were larger than in 2019,but there was no significant difference in fruit shape index between treatments.The N70%+C,N85%+C,N100%+C and N0%+C treatments significantly reduced the peel thickness in 2018,but this significant difference was not observed again in 2019.There was no significant difference in the indicators of peel surface smoothness and peel color between the treatments in 2018 and 2019.In 2018,there was no significant difference in the intrinsic quality of citrus fruits in various treatments.In 2019,the titrable acid content of N70%+C,N85%+C,and N100%+C treatment was significantly lower than that of CF and N0%+C treatment.The ratio is significantly higher than CF and N0%+C treatment.There were no significant differences in the indicators of fruit residues between treatments.(3)The nitrogen utilization rate of N70%+C treatment is significantly higher than that of CF treatment,and the nitrogen utilization rate of N85%+C and N100%+C treatments is not significantly different from that of CF treatment in 2018 and 2019.Compared with CF treatment,N70%+C and N85%+C treatments have higher economic benefits in 2018 and 2019,and the improvement range is between 2%-12%(4)The contents of TC,TN,TP,TK and trace elements in the treated leaves were basically the same during different sampling periods.There was no significant difference in the content of nutrients measured during the same sampling period between treatments.The TC content of N70%+C,N85%+C and N100%+C treated leaves was higher than that of CF treatment,while the TN content of N0%+C treated leaves was lower than other treatments during most of the sampling time.(5)The soil SOM,TN,available P,available K and available Ca,Mg,Fe,Mn,Cu,Zn contents of the treatments in the same sampling period are not significantly different,N70%+C,N85%+C,N100 %+C and N0%+C treatments showed higher SOM content than CF treatment in the samples at the end of 2018 and 2019,and N0%+C showed lower TN content in other treatments at the end of 2018 and 2019.Therefore,on the basis of conventional fertilization in Dangyang area of Hubei Province,it is recommended to apply cake fertilizer and reduce the input of chemical nitrogen fertilizer by 30%.