| Tea has become a major cash crop in Zhejiang Province.In order to increase the tea production,the reduction of fertilizer efficiency and agricultural non-point source pollution caused by long-term extensive application of chemical fertilizers have become serious problems.Biogas slurry is rich in organic matter,nitrogen,phosphorus and potassium,which can be directly absorbed by crops.Biochar,produced by hightemperature pyrolysis and carbonization,can be used as modifiers and fertilizer carriers to improve soil quality and maintain soil fertility.Tea gardens are widely distributed and the soil varies greatly.Therefore,it is necessary to adapt to local conditions and rationally apply scientifically to improve the soil and tea quality of tea gardens.This paper takes swine manure biochar,biogas slurry and Zhejiang acidified tea garden soil as research objects.Firstly,pot experiments were conducted to explore the effects of different amounts of 350℃ and 500℃ pyrolysis biochar,biogas slurry and biogas slurry-biochar combined application on soil nutrient content and enzyme activity;Secondly,carry out the field experiment of tea garden to study the effects of biogas slurry and biochar on the soil remediation of acidified tea garden and the improvement of tea quality.It put forward the best scheme for the application amount of biogas slurry and biomass carbon and expected to provide a theoretical basis for the rational application of biogas slurry and biochar and the sustainable development of tea garden.The main results are as follows:(1)The results of pot experiment showed that: biogas slurry increased the soil p H value by 0.65,and the contents of soil nitrogen,phosphorus and potassium,and the activities of sucrase,urease,phosphatase and catalase increased with the increasing of biogas slurry addition.After 60 days of application of biogas slurry,the total nitrogen and sucrase of 150%N increased the most by 10.00% and 48.68% compared with CK in the same period.The application of swine manure biochar can significantly improve the soil p H value,nitrogen,phosphorus,potassium and enzyme activity,and the effectiveness increased with the increasing of biochar addition.Effect of biochar that pyrolysis in 350℃ on soil quality was better than that of in 500℃.The effect of combined application of biogas slurry and swine manure biochar on improving soil quality is better than that of single application of biogas slurry and biochar.The most significant improvement of soil nutrients content was observed when the addition rates of biogas slurry and biochar were 100% N and 2%,respectively.(2)The results of tea garden experiment showed that: Application of biogas slurry can improve the soil p H value,prevent soil acidification,the contents of soil nitrogen,phosphorus and potassium,and the activities of sucrase,urease,phosphatase and catalase increased first and then decreased with the increasing of biogas slurry addition.The effect of combined application of biogas slurry and chemical fertilizer is better than that of single application of chemical fertilizer.The best is N3H1(75%N),content of available phosphorus increases by 81.63% under this treatment.The application of biochar can significantly improve the soil quality,and the effectiveness increased with the increasing of biochar addition.The catalase activity at 2% application rate increased by 71.43%.The improvement effect of swine manure biochar on soil quality is better than that of rice straw biochar.(3)The application of biogas slurry and swine manure biochar significantly increased the contents of biochemical components and mineral elements in tea,and reduced the phenol ammonia ratio of fresh tea.With the increase of biogas slurry application,the lifting effect of tea is gradually weakened.This study found that N3H1(75%N)and A2(2% biochar)had better effect on the improvement of tea quality.Under the treatment of biogas slurry and biochar,the contents of Cr,As,Cd and Pb in tea are far lower than the limit standard in the national standard of tea. |
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