Effects Of Drip Fertigation Levels Combined Coffee Peel Returning Ways On Soil Quality And Coffee Arabiaca’s Physiologial And Ecological Characteristics

Coffee arabica is the characteristic economic crop of Yunnan Province,but the long-term irrational use of inorganic fertilizer has damaged the soil environment and hindered the sustainable development of Coffee arabica in the local area.Therefore,it is of great significance to study the fertilization management methods to improve soil quality.In this study,1-year-old Coffee arabica was used as the experimental material,4 organic fertilizers types（S₀:non-coffee peel returned to the field;S₁:coffee peel biochar returned to the field;S₂:coffee peel composted returned to the field;S₃:coffee peel burned returned to the field）and 4 inorganic fertilizer level(no fertilizer M₀:0 g·tree^-1;low fertilizer M₁:6 g·tree^-1;medium fertilizer M₂:12 g·tree^-1;high fertilizer M₃:18 g·tree^-1)were set to carry out plot experiment with complete combination.This paper studied the effects of organic and inorganic fertilizer combined application on soil physical and chemical properties,soil biological properties and physiological ecology characteristics of coffee under the coupling of drip irrigation fertilizer and coffee peel returning mode,and the soil quality and comprehensive benefits of each treatment were evaluated.Important results were as follows:（1）Except S₃ treatment had no significant effect on soil moisture content,other treatments increased soil moisture content by 11%～58%compared with M₀S₀,among which M₂S₁ treatment was the maximum of all treatments reached 30%.Compared with M₀,M₂ treatment increased soil moisture content the most,and compared with S₀,S₁ treatment increased soil moisture content the most obviously.Compared with M₀S₀,soil pH decreased by 8%under all compost treatments,and increased by 2%～6%in other treatments.Fertilization reduced soil bulk density and increased soil porosity,and the minimum soil bulk density of all treatments was 1.33g·cm^-3（M₂S₁）.（2）Compared with M₀S₀,fertilization greatly increased the soil nutrient content.With the increase of inorganic fertilizer level,the contents of soil total nitrogen and organic matter increased first and then decreased,while the contents of soil available nutrients increased.The order of soil nutrient contents under different organic fertilizer treatments was S₂>S₁>S₃>S₀（the order of organic matter was S₂>S₁>S₀>S₃）.Among all treatments,M₂S₂ had the maximum total nitrogen and organic matter,and M₃S₂ had the largest available soil nutrients.（3）Compared with M₀S₀,fertilization increased the number of soil microorganisms and the activity of soil enzymes.The number and activity of soil biological characteristics increased first and then decreased with the increase of inorganic fertilizer level,and showed the order of S₂>S₁>S₃>S₀ under organic fertilizer treatment.Among all treatments,the treatment with the largest number of microorganisms and the highest enzyme activity was M₂S₂.（4）Compared with M₀S₀,fertilization treatments increased the net photosynthetic rate by 5%～67%,the instantaneous water use efficiency by 13%～68%（except M₃S₀）,the stomatal conductance by 20%～140%（except M₀S₂ and M₁S₂）,and reduced the intercellular CO₂ concentration by 8%～42%.All the above photosynthetic indexes increased first and then decreased with the increase of inorganic fertilizer amount.Compared with S₀,net photosynthetic rate,stomatal conductance and intercellular carbon dioxide concentration were the highest under S₁ treatment,while leaf water use efficiency was the highest under S₂treatment.（5）Compared with M₀S₀ treatment,fertilization promoted the growth of Arabica coffee.The total increment of plant height,stem diameter,crown width and leaf number increased by 75%～329%,25%～79%,21%～153%and 58%～208%under different fertilization treatments.The total increment of coffee growth index increased firstly and then stabilized with the increase of inorganic fertilizer.Compared with S₀,S₁ and S₂ significantly improved the growth of coffee,in which the total increment of plant height and stem diameter under S₁ treatment was the largest,and the total increment of crown width and leaf number under S₂ treatment was the largest.Soil moisture content,porosity,nutrient content,microbial number,enzyme activity,photosynthetic performance of leaves and growth amount of coffee seedlings under different fertilization measures basic size of organic and inorganic fertilizer>organic fertilizer or inorganic fertilizer single>no fertilizer.Comprehensive analysis showed that M₂S₂（soil quality index is 0.867,is the maximum value of each treatment,the comprehensive score of the first）was the most beneficial treatment for improving soil quality and promoting physiological and ecological development of coffee seedlings.