| Tea(Camellia sinensis(L)O.Ktze.)is an important leaf crop in tropical and subtropical regions.China is the world’s first tea plantation country with 43.2%of the world ’s tea cultivated area ranking first in the world.According to the yearbook in 2015,the total area of China’s tea cultivation was 287.7 million ha and the yield of dry raw tea was 227.8 million ton.The application of nitrogen fertilizer(especially ammonium fertilizer)is an effective means for obtaining high yield in tea cultivation.However,large amounts of nitrogen fertilizer application in tea plantation can inevitably lead to soil acidification and fertility decline.Meanwhile,the activity of soil microbial metabolism and the stability of microbial community structure can be affected by the change of tea rhizosphere situation.Furthermore,the absorption and utilization of nutrients in tea rhizosphere can also be affected and thus impact on the yield and quality of tea.Therefore,studying the different fertilization is crucial for the restoration of soil fertility and the sustainable development of tea planting industry.In this study,the field trial was conducted in the tea garden continuously ratooned and monocultured for 20 year,which is located in oriented field experimental station of Fujian Agriculture and Forestry University,Taozhou town of Fujian province.Throughout the study more than 20 kinds of exotic leguminous grass from America were intercropped with tea plant,the Laredo soybean was selected as green manure for fertility restoration.This cultivar is highly palatable for goat,in return the manure from the goats that feed on Laredo soybean was also taken as organic fertilizer for restoration.Different types of NPK with same level of application(urea-based nitrogen fertilizer,legume forage-based green manure,goat manure-based organic fertilizer)were applied to determine their effect on soil fertility,microbial activity and community structure in tea rhizosphere soil.The present study was conducted to further evaluate the effect of rhizosphere ecological restoration on degraded tea garden based on "Tea-Legume Forage-goat manure".Finally,the outcome of this study has revealed that physiological traits of the new sprouts and the biochemical components of new tea leaves have statistically proven that fertilization mode,intercropping tea crop with legume forage and browsing of tea plant by goats is a good agriculture management practice,helping to promote plant growth,yield and increase soil nutrients in tea plantation.The main conclusions drawn from the findings of this study are as follows:1.Compared with the rhizosphere soil of tea plant without fertilization,the acidity of tea rhizosphere soil can be improved by"legume forage-goat manure".The pH value was increased from 4.23 to 4.32,meanwhile the content of exchange acid was decreased by 1.34 cmol·kg-1(exchange Al3+ been decreased by 0.29;exchange H+ been decreased by 1.04).The pH was a little lower than before nitrogen fertinizer application,and exchange Al3+ was increased to 2.88 cmol·kg-1.2.The release of effective nutrient in tea rhizosphere was obviously promoted by ";legume forage-goat manure".The content of NH4+-N was increased by 4.17 mg·kg-1,NO3-N was increased by 1.61 mg·kg-1;AP was increased by 5.16 mg·kg-1;AK was increased by 0.28 mg·kg-1;exchange Ca2+ was increased by 0.55 cmol·K-1.The result showed that the content of AP was obviously decreased by 14.32 mg·kg-1 with nitrogen fertilizer in tea rhizosphere.The fertility of tea rhizosphere soil would be maintained by "legume forage-goat manure",EB was increased by 0.57 cmol·kg-1,BS was increased by 6.0%.3.The secretion of oxalic acid in tea rhizosphere was helpful for the release of Ca and Mg(r=0.655);interestingly,the secretion of tartaric acid and acetic acid promoted the activation of P(r=0.767),the result showed that the content of acetic acid was increased by 332.02 mg·kg-1,as the same time the AP was also increased by 5.16 mg·kg-1 with "legume forage-goat manure".Meanwhile,the content of acetic acid was decreased by 60.67 mg·kg-1,as well as AP by 14.32 with nitrogen fertilizer.It can be considered that "legume forage-goat manure" can affect the release of relevant nutrients through affecting the secretion of low molecular weight organic acids,it can as well improve rhizosphere soil barren nutrient library.4.The Fertilizer mode can effectively improve the enzyme activity of tea rhizosphere soil,for instance,the activity of urease and invertase was promoted by 7.15 mg·g-1·24h-1 and 5.66 mg·g-1·24h-1,respectively.Likewise,the activity of acid phosphatase and polyphenol oxidase sharply increased by 1.98 mg·g-1·h-1 and 40.66 mg·g-1·h-1,respectively.Meanwhile,fertilizer mode significantly improved microbial biomass C,P in tea rhizosphere,for example SMB-C and SMB-P were improved by 81.25mg·kg-1 and 1.01 mg·kg-1,respectively.However,the activity of acid phosphatase was obviously decreased by nitrogen fertilizer as a result it can lead to reduce the usage efficiency of P fertilizer in the tea garden.5.The mode can obviously increase the Shannon diversity index and richness index of tea rhizosphere soil bacteria as indicated by Chaol which was up to 3195.25 from 2337.66,the ACE was up to 2933.08 from 2409.It was however noted that nitrogen fertilizer application had no significant effect on diversity and richness indexes of tea rhizosphere soil bacteria.Proteobacteria(35.91%),Acidobacteria(23.22%),Chloroflexi(12.27%),Actinobacteria(8.23%)were major bacteria in tea rhizosphere soil.Xanthomonadales(7.34%),Burkholderiaceae(2.69%),Rhodobacterales(2.42%)were major bacteria at the level of family with Proteobacteria in tea rhizosphere soil.Most of bacteria were kinds of plant pathogens in the Xanthomonadales,the result showed that the relative abundance of Xanthomonadales was reduced with 8.99%,11.76%by "legume forage-goat manure" and nitrogen fertilizer,respectively.Most of bacteria could break down aromatic compounds in the Burkholderiaceae,the relative abundance of Burkholderiaceae was increased by 1.36%with the mode,and however,it was not significantly different with N fertilizer application.Furthermore,the study identified Rhizobium which is a kind of nitrogen-fixation bacteria,the relative abundance of Rhizobium was increased by 0.88%with this mode,and there was a downward trend in N fertilizer.6.Application of "legume forage-goat manure" into tea rhizosphere,new tea sprout’s length was improved by 44.91%,and the content of the third leaf’s Chlorophyll with new sprouts was increased by 8.54%,and the net photosynthetic rate of this leaf was improved by 6.78%.Moreover,the sprout’s length was improved by 42.06%,the content of third leaf’s Chlorophyll was increased by 4.42%,and the Pn of the leaf was increased by 5.96%.Meanwhile,the hundred-buds dry weight was improved by "legume forage-goat manure"(59.34%),and yield of dry tea was improved by 16.88;Overall hundred-buds dry weight was improved in N fertilizer(16.88%)and the yield of dry tea was improved as well(13.15%).7.Tea polyphenols were decreased by 13.71%with N fertilizer,however,it was remarkably improved by 32.24%with "legume forage-goat manure";free amino acid content in new tea leaf was significantly increased by fertilization,10.01 g·kg-1 by this mode,9.52 g·kg-1 by N fertilizer;theanine was increased by 0.19 g·kg-1 with this mode,increased by 0.29 g·kg-1 with N fertilizer;phenolic/ammonia ratio was significantly decreased by fertilization(the mode:67.49%,N fertilizer:78.04%).Furthermore,Caffine was also increased by fertilization(the tea-legume forage-goat manure mode:14.76%,N fertilizer:27.89%). |
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