Hazard Assessment on Heavy Metal Pollution in Surface Soil from Tea Gardens of Wuzhishan

[Objective] The aim of this study is to investigate hazard assessment on heavy metal pollution in surface soil from tea gardens of Wuzhishan. [Method] The average content and accumulation status of heavy metals including Cr,Ni,Cu,Zn,As,Cd and Pb in surface soil from tea gardens of Wuzhishan was collected. Taking the highest global background value of heavy metals in sediments before modern industrialization and the first-class natural background value of Soil Environment Quality Standard in China as the reference value respectively,the accumulation or ecological hazard coefficient and the ecological hazard index of heavy metals in surface soil from tea gardens of Wuzhishan were assessed by potential ecological risk index. [Result] The pollution level with two kinds of background values as the reference value was similar,while Cd and Pb were main heavy metals which had potential impact on ecological environmental in surface soil from tea gardens of Wuzhishan. [Conclusion] The potential risk level of heavy metals in surface soil from tea gardens of Wuzhishan belongs to the slight-medium pollution level,and the heavy metal with potential risk is mainly Cd.

Species Investigation and Population Dynamic of Spiders in Tea Gardens in Northern Guangxi

A systematic investigation on spiders in a tea garden of Guilin Institute of Tea Sciences was conducted. The results showed that totally 687 specimens were collected, belonging to 34 species, 27genera, 14 families, 2 suborders, and a new record species Trochosa suiningensis in Guangxi was found. Spider is a ma- jor developing natural enemy group of insect pests in tea garden, with features of wide distribution, large quantity, long duration, strong predatory and stress resist- ance, which has strong predation on adults and nymphs of Empoasca vitis and young larvae of Ectropis oblique. The population of spiders in tea garden significantly increases after middle June, and reaches the peak in July and August every year.

Effects of Different Farming Methods and Their Effects on Soil Physicochemical Properties of Guilin Maojian Tea Gardens

In order to further optimize the cultivation and agronomic technology of Guilin Maojian tea gardens, the effects, efficiencies and costs of different farming methods and their effects on the physiochemical properties of tea garden soil were studied through the modification of the test sites with the non-farming land as the control. The results showed that human farming, mini-tiller farming and crawler tractor farming could improve the physical and chemical properties of soil. After farming, the soil had good water retention but low moisture content compared to the control group, while the soil bulk density and hardness value were significantly lower than those of the control, and the porosity of soil was significantly higher than that of contrast. With the passage of time, soil bulk density and hardness value gradually increased after farming, while the porosity of soil decreased gradually. There were great differences in the effects, efficiencies and costs of different farming methods. Crawler tractor had the best and most stable farming effect, and the operation efficiency was 10 times that of human farming while the cost was only 0.39 times of human farming. Therefore, it was feasible to adopt mini-tiller or crawler tractor to carry out mechanical farming of Guilin Maojian tea garden, which provided theoretical references for the soil property improvement using mechanical farming and was favorable for promoting the popularization of farming machines and the acceleration of mechanization of tea gardens. But for tea plantations that are intended to be mechanized, apart from the mechanical and technical personnel to be configured in place, the site conditions, planting modes and mechanical way reservation of tea garden should be planned accordingly. It is recommended to select flat or gentle slope for reclamation, and preference is given to non-sexual tea tree varieties with big line spacing over 180 cm long. Moreover, the main road construction should be more than 3.0 m, and trunk road 2.0 m or above. And isolation ditch and drain should be set between the tea garden and the surrounding mountain forests and farmland.

Research Progress and Prospect of Intelligent Tea Garden Technology Application

The development and application of internet plus modern tea industry technology is more and more extensive.As an important part of the development process of tea industry,intelligent tea garden plays an important role in the development of the whole industry.At present,intelligent tea garden technology is widely used in many fields such as intelligent monitoring,water and fertilizer integration,green prevention and control,quality and safety traceability.In this paper,the application of intelligent tea garden technology in tea gardens was reviewed.On this basis,the development trend of new information technology and tea industry was prospected,in order to provide some reference and thinking for the innovative research of new technology in tea garden in the future.

Effects of Continuous Irrigation of Biogas Slurry on Forms and Biological Availability of Pb in Soil of a Tea Garden

Through indoor culture experiments, the effects of continuous irrigation of biogas slurry on the forms and biological availability of Pb in soil of a tea garden were studied. The results show that continuous irrigation of biogas slurry could change the forms of Pb in the soil, and exchangeable Pb, Pb bonded to iron and manganese oxides, and Pb bonded to carbonates transformed to Pb bonded to or- ganic matter and residual Pb in the soil. Among various forms of Pb in the soil, the content of residual Pb was the highest in the soil irrigated with biogas slurry contin- uously in various treatments, accounting for 54.56%, 60.00% and 60.70% in the treatments T1, T2 and T3 respectively. Compared with the CK, the application of bio- gas slurry could decrease the biological activity and biological availability of Pb in the soil obviously, and the reduction of the biological activity was 21.26%-22.83%. In a word, the application of biogas slurry in soil of the tea garden could inhibit the biological activity and biological availability of Pb.

Distribution of Aluminum and Fluoride in Tea Plant and Soil of Tea Garden in Central and Southwest China

The distribution of Al and F contents and the relationship between Al and F in tea plants and soils of 12 tea gardens in Central and Southwest China were investigated from October 31 to November 14, 2006. The results show that there were differences in pH, CEC, the contents of organic matter （OM）, Al and F in the different soils of the tea gardens. The Al content ranged from 1196 to 7976mg/kg for old leaf, 370 to 2681mg/kg for young leaf and 285 to 525mg/kg for stem, whereas the content of F ranged from 221 to 1504mg/kg for old leaf, 49 to 602mg/kg for young leaf and 13.5 to 77.5mg/kg for stem. The concentrations of labile Al varied obviously in the different soils, but the distribution law of labile Al content for the same garden was Alexchangeable≈AlFe.Mn oxide〉Alorganic〉mlwater.soluble. The contents of different labile F fractions varied slightly in the different soils and the different soil layers, though the exchangeable F content was lowest among the labile F in the soils. The concentrations of Al and F in tea plants increased with increasing amount of water-soluble Al or F, especially the amount of water-soluble fractions in the soil layer of 0-20cm. The correlation between Al content and F content in the tea leaf was more significant than that in the tea stem. Furthermore, the correlation between Al content and F content in whole tea plant was strongly significant （r=0.8763, p〈0.01, n=36）. There were evident tendency that Al concentration increased with the increase of F concentration in different soil layers. The correlation of water-soluble Al with water-soluble F in all soils was also strongly significant （r=0.7029, p〈0.01, n=34）. The results may provide a proof that Al and F are jointly taken up by tea plants to some extent in natural tea gardens.

Bioavailability of heavy metals in soil of the Tieguanyin tea garden, southeastern China

The bioavailability of 22 heavy metals was investigated at 19 sampling sites in Tieguanyin tea garden in Anxi County,Fujian Province,southeastern China.Heavy metal concentrations were determined by inductively coupled plasma-mass spectrometry(ICP-MS)and evaluated by geo-accumulation index(I_(geo)).Dilute nitric acid extraction was used to evaluate biological activity.Cu,Pb,and Cd were highly bioavailable and most easily absorbed by tea trees.Heavy metal bioavailability in the surface soil was as the ratio of the effective state to the total amount.Cd had the highest I_(geo)values,and the respective samples and sites were classified as moderately/strongly contaminated.Cd element is considered the main factor of heavy metal pollution in the tea garden in Anxi.The other heavy metals studied were present in lower concentrations;thus,the samples were classified as uncontaminated or slightly contaminated.

Soil Microbial Community Structure in Diverse Land Use Systems:A Comparative Study Using Biolog,DGGE,and PLFA Analyses

Biolog, 16S rRNA gene denaturing gradient gel electrophoresis （DGGE）, and phospholipid fatty acid （PLFA） analyses were used to assess soil microbial community characteristics in a chronosequence of tea garden systems （8-, 50-, and 90- year-old tea gardens）, an adjacent wasteland, and a 90-year-old forest. Biolog analysis showed that the average well color development （AWCD） of all carbon sources and the functional diversity based on the Shannon index decreased （P 〈 0.05） in the following order： wasteland 〉 forest 〉 tea garden. For the DCCE analysis, the genetic diversity based on the Shannon index was significantly lower in the tea garden soils than in the wasteland. However, compared to the 90-year-old forest, the tea garden soils showed significantly higher genetic diversity. PLFA analysis showed that the ratio of Gram positive bacteria to Cram negative bacteria was significantly higher in the tea garden soils than in the wasteland, and the highest value was found in the 90-year-old forest. Both the fungal PLFA and the ratio of fungi to bacteria were significantly higher in the three tea garden soils than in the wasteland and forest, indicating that fungal PLFA was significantly affected by land-use change. Based on cluster analysis of the soil microbial community structure, all three analytical methods showed that land-use change had a greater effect on soil microbial community structure than tea garden age.

Soil Acidification of Alfisols as Influenced by Tea Cultivation in Eastern China

Soil acidification is an important process in land degradation around the world as well as in China.Acidification of Alfisols was investigated in the tea gardens with various years of tea cultivation in the eastern China.Cultivation of tea plants caused soil acidification and soil acidity increased with the increase of tea cultivation period.Soil pH of composite samples from cultivated layers decreased by 1.37,1.62 and 1.85,respectively,after 13,34 and 54 years of tea plantation,as compared to the surface soil obtained from the unused land.Soil acidification rates at early stages of tea cultivation were found to be higher than those at the later stages.The acidification rate for the period of 0-13 years was as high as 4.40 kmol H + ha ?1 year ?1 for the cultivated layer samples.Soil acidification induced the decrease of soil exchangeable base cations and base cation saturation and thus increased the soil exchangeable acidity.Soil acidification also caused the decrease of soil cation exchange capacity,especially for the 54-year-old tea garden.Soil acidification induced by tea plantation also led to the increase of soil exchangeable Al and soluble Al,which was responsible for the Al toxicity to plants.

Soil Characteristics and Nutrients in Different Tea Garden Types in Fujian Province, China

Anxi is the largest producing area of Tie Guanyin tea in China. “The cultural system of Tie Guanyin tea in Anxi” was selected as “Nationaly Important Agricultural Heritage Systems” （China-NIAHS） in 2014. Tea gardens in this region are organic, ecological or non-ecological. After sampling the soil in these three kinds of tea gardens, we compared soil properties and nutrient content at different soil depths using physical and chemical analyses. Our aim was to provide a scientiifc basis for the management of tea plantations. We measured and analyzed soil in two organic, three ecological and one non-ecological tea gardens at depths of 0–10 cm and 10–20 cm in Anxi County. According to Duncan multiple comparisons and t tests, soil nutrients differed between organic and ecological or non-ecological tea gardens at 0–10 cm. Organic matter and total nitrogen differed between organic and non-ecological tea garden soils at 10–20 cm. In organic tea gardens, soil bulk density, porosity, relative water content, soil organic matter, total nitrogen and total phosphorus were advantageous for tea tree growth. In ecological tea gardens, the indicators were appropriate and relatively advantageous for tea tree growth at a soil depth of 0–10 cm. For non-ecological tea garden, the nutrients were at a compact level and negatively affect tea growth. These results show that soil properties and nutrient content in organic and ecological tea gardens are superior to non-ecological tea garden. The development of organic tea gardens is the most suitable strategy for the growth of tea trees.

INTERCROPPING TEA PLANTATIONS WITH SOYBEAN AND RAPESEED ENHANCES NITROGEN FIXATION THROUGH SHIFTS IN SOIL MICROBIAL COMMUNITIES

Intercropping with eco-friendly crops is a well-known strategy for improving agriculture sustainability with benefits throughout the soil community,though the range of crop impacts on soil microbiota and extent of feedbacks to crops remain largely unclear.This study evaluated the impacts of different intercropping systems on soil bacterial community composition,diversity,and potential functions in tea gardens.Intercropping systems were found to be significantly influenced soil microbiota.Within the three tested intercropping systems(tea-soybean,tea-rapeseed and tea-soybean-rapeseed),the teasoybean-rapeseed intercropping system had the most dramatic influence on soil microbiota,with increases in richness accompanied by shifts in the structure of tea garden soil bacterial networks.Specifically,relative abundance of potentially beneficial bacteria associated with essential mineral nutrient cycling increased significantly in the tea-soybean-rapeseed intercropping system.In addition,soil microbial functions related to nutrient cycling functions were significantly enhanced.This was in accordance with increasing relative abundance of nitrogen cycling bacteria,including Burkholderia spp.and Rhodanobacter spp.Based on these results,it is proposed that intercropping tea plantation with soybean and rapeseed may benefit soil microbiota,and thereby promises to be an important strategy for improving soil health in ecologically sound tea production systems.