Production Status Of Pepper In Wenshan And Application Evaluation Of Special Fertilizer

Pepper is the second largest vegetable crop in China,large amount of fertilizer application and unreasonable nutrient input in pepper production in Southwest China is commonly existed.At the same time,the high temperature and high rain in this region lead to serious reactive nitrogen loss,low fertilizer utilization rate,and serious environmental problems.Those problems severely restricted the green production of peppers in the region.Therefore,this study took Wenshan pepper as the research object,and conducted the combining method of farmer survey and life cycle assessment.We have quantitatively revealed the nutrient resource input and environmental cost from pepper production system in Wenshan county,and analyzed the mitigation potential of various environmental costs and limiting factors.According to the soil-crop nutrient supply law,a new type of special fertilizer for pepper was designed.Meanwhile,we conducted a field experiment to comprehensively evaluate the effects of the special fertilizer on agronomic,environmental cost.The main results are as follows:1.Based on farmer surveys and life cycle assessment analysis,the results show that the pepper production system in Wenshan county has been characterized as high input of nutrient resources and high environmental costs.The application rate of nitrogen（N）,phosphorus（P） and potassium（K）inputs were 417 kg ha^-1,170 kg ha^-1 and 160 kg ha^-1,meanwhile the greenhouse gas（GHG）emission,reactive N loss,acidification potential and eutrophication potential on per hectare unit of pepper production were 6210 kg CO₂eq ha^-1,127 kg N ha^-1,48.9 kg PO₄-eq ha^-1and 101 kg SO₂eq ha^-1,respectively.On the other hand,Wenshan pepper had lower yields,with an average yield of 14 t ha^-1.On per tonne unit of pepper production,the greenhouse gas（GHG）emission,reactive N loss,acidification potential and eutrophication potential were 541 kg CO₂ eq t^-1,11.0 kg N t^-1,4.28 kg PO₄-eq t^-1and 8.8 kg SO₂ eq t^-1,respectively.Fertilizers were the major contributor to every environmental costs,accounting for 92.0%～98.2%of all environmental costs.2.The potential of environmental cost reduction and yield increase has been quantified through grouping of farmers for the Wenshan pepper production system.Our results showed that there was a large difference in the nutrient input and environmental cost among farmers.Compared with the average of all farmers,the high-yield and high-PFP-N（HH）group significantly increased the pepper yield by 32.8%with the reducation of N,P fertilizer rate by 20.4%,10.6%,and the growth of K fertilizer rate by 29.0%.In terms of environmental cost,the greenhouse gas（GHG）emission,reactive N loss,acidification potential and eutrophication potential in high-yield and high-PFP-N（HH）group on per tonne unit of pepper production decreased by 62.9%,68.1%,69.1%and 66.4%,respectively.The results of group analysis showed that optimizing nutrient management based the best farmers could significantly increase the pepper yield with lower environmental costs.3.Based on the soil-crop nutrient supply regulation,a new type of special fertilizer for pepper was designed through combination with optimizing the nutrient ratio,adjusting N fertilizer form,applying the medium and trace,and applying nitrification inhibitor.Our result of field experiment in 2021 show that the new type of special fertilizer for pepper reduces the amount of fertilizer by 13.6%,increases the yield by 26.7%,reduces the nitrate by 32.2%,reduces the N surplus by 77.7%compared with the farmers’practices,and improves nitrogen use efficiency by 19.9%.At the same time,compared with the farmers’practices,the new type of special fertilizer for pepper reduces the environmental cost by 50.7%～65.7%,and increases the net economic benefit and net economic benefit of the ecosystem by 33.3%,and 44.5%,respectively.