Effects Of Biomass And Reduced Fertilizer On Nitrogen And Phosphorus Loss In The Surface Runoff And Soil Fertility Effect Of Tea Garden

Tea tree is a perennial evergreen woody plants and an important economic crops in many countries.The soil environment is important factor producing impact on tea production for its leaf yield and quality.Soil fertility directly affects the tea yield and quality and many producers use chemical fertilizers to increase the tea yield.Excessive fertilizer not only reduce the fertilizer use efficiency and lead to soil acidification,but also produce negative impact on water quality and ecological environment function.Many research have found that the biomass carbon(biochar)can enhance the content of soil organic carbon and phosphorus,improve soil structure,adjust soil pH value,etc.Some research also indicates that biochar addition with fertilizer mixing is better for soil properties.To study the effect of fertilizer rate with biochar addition in tea garden on soil nutrients behavior,it is important to understand the mechanism of the tea garden soil nutrient change and its transferring process.A field experiment was arranged in the tea field located in Jing Shan Township.The tea garden soil planted with 35 years,as the research field,was treated with three different fertilizer rates(N200(reduced 20%)、N225(reduced10%)、N250(normal N input))respectively and plus 10 t/hm2 biochar input under reduced N input in tea garden.To compare the biochar application rate on the N and P loss in tea soil under the condition of the conventional fertilization addition,0(N250),10 t/hm2(N250B10),20 t/hm2(N250B20)and 40 t/hm2(N250B40)four different addition amount of biochar input were arranged at the same time in the tea garden so as to analyze output form of nitrogen and phosphorus nutrition in runoff.To explore the different fertilizer rate with biochar caused by the differences of soil physical and chemical properties,the environmental effects of biochar input in tea garden were evaluated scientifically.The main research results are as follows:(1)Under the condition of natural rainfall influence,tea garden soil produced high concentration of nitrogen and phosphorus in surface runoff.The loss of nitrogen was mainly in the form of NO3--N.Under the condition of conventional fertilization(250 kg N/hm2),total nitrogen loss in the runoff was 20.78 kg/hm2,and total phosphorus loss 0.37 kg/hm2.Adding biochar significantly reduced the ammonia nitrogen(NH4+-N),nitrate nitrogen(NO3--N),total nitrogen(TN)and total phosphorus concentration(TP)in tea garden surface runoff.When biochar addition was at 20 t/hm2,ammonia nitrogen(NH4+-N),nitrate nitrogen(NO3--N),total nitrogen(TN)and total phosphorus(TP)reduction rate was at 30.2%,23.2%,16.2%and 24.8%respectively as compared to without biochar treatament.Biochar addition amount of 40 t/hm2 can reduce the ammonia nitrogen(NH4+-N),nitrate nitrogen(NO3--N),total nitrogen(TN)and total phosphorus(TP)reduction loss rate by 21.7%,27.2%,23,8%and 19.2%.respectively:(2)Applying biochar can significantly enhance the tea garden soil pH value.The treatment of N225B10(225kg N/hm2 plus 10t/hm2 biochar)obtained a better results on soil pH value improvement.Compared with N225 treatment group,the soil pH value of N225B10 treatment group increase of 1.5%in 2017.Biochar could significantly increase soil carbon,nitrogen and phosphorus nutrient content.When the nitrogen application rate was at N200,N225 and N250 in 2017,compared with pure fertilization treatment group,adding biochar treatment group can increase the CEC by 0.39 cmol/kg,0.64 cmol/kg and 0.72 cmol/kg,the increase of soil organic matter were 0.06 g/kg,0.17 g/kg and 0.08 g/kg,soil total nitrogen content increase 7.7%,1.2%and 5.5%,the extent of soil available phosphorus content increase 21.8%,8.7%and 8.9%,respectively.(3)Tea production is closely related to nitrogen conditions and supplement rates,the tea yield increased with the increase of nitrogen application rates.The yield of tea leaves in the N250B40 treatment was 102.9%of the N250 treatment group without biochar addition at 40 t/hm2.Compared with N225 treatment group,the yield of tea leaves of N225B10 treatment increase of 1%.