The Study On Soil Acidification Dynamic And Adjustment Measures Of Typical Tea Gardens In Jiangsu Province

The soil environment quality of tea garden is one of main factors affecting the tea yield and quality. Severity of soil acidification of tea garden has gradually become one of the outstanding problems in tea production. Jiangsu province is one of primary tea production provinces in China, which is also important production base for the export tea. The related research indicated that tea garden soil in Jiangsu exists acidified phenomenon with different degree and presents the tendency of acidification intensified. Soil acidification of tea garden will make more the mobility of heavy metal and fluorine transfer into tea. Recently, the over standard of tea lead and fluorine in Jiangsu province has great relationship with severe acidification of tea garden soil. By location investigation, incubation experiment and field trail, the paper analyzed the soil acidification status and development trend of typical tea plantations in Jiangsu province and discussed soil properties restricting tea garden soil acidification. At the same time, the article carried out the study on adjustment measures of tea garden soil acidification, which compared the improvement effect on acidic tea garden soil with different modifiers, in order to find the technical way on active controlling acidification harm of tea garden soil, thus providing theoretical and practical significance in instructing tea production and tea garden soil management. In this article, results are as follows:The results of location on 21 typical tea plantations in Jiangsu province between 2008 and 2010 indicated that tea garden soil acidification displayed very serious. Tea garden soil pH values were all lower than the optimum pH5.5 for tea growth, among which, pH value lower than 4.0 accounts for 42.8 percent. Combined the location monitor data from recent research and previous studying team, from 2003 to 2010, surface soil pH decrease rate of tea garden in Jiangsu province showed an observed variation in the present study, which increased firstly but decreased later year by year and the maximum value was observed in 2007. Partial tea garden subsoil (below soil depth 20cm) in Jiangsu province presented the tendency of increased acidification. Subsoil pH decrease rate enhanced along with soil depth increasing and the phenomenon of tea garden soil acidification would be serious situation developing to depth.On the basis of analyzing soil acidification status and development trend of typical tea plantations in Jiangsu province, simultaneously we determined soil physical and chemical properties of tea gardens. The result showed that a very significant positive relationship was found between tea garden soil pH decrease rate and its initial pH value in observation period and its proportion of exchangeable Al in exchangeable acid; a yery significant negative relationship is found between tea garden soil pH decrease rate and soil organic matter content and total exchangeable bases while significant negative relationship is found with soil clay content, cation exchange capacity and exchangeable calcium. Furthermore, tea garden soil pH decrease rate is affected by the intensity and frequency of acid rain in selected study area.In order to proceed field trail on acidic tea garden soil for the later period, incubation experiment was carried out. According to the relation between soil properties and soil pH,6 single and mixed improvers with different types and characteristic including biological carbon ash, ect. were selected to modify tea garden soil with different acidification degree. The result indicated that acidification degree of tea garden soil was lower, soil pH increasing amplitude after using improvers was higher.6 kinds of modifiers applying to acidic tea garden soil could enhance soil pH, which had an order from high to low in turn: Straw dry distillation fluid> Lignin sludge> fly ash> Mixture between fly ash and lignin sludge> Mixture between fly ash and straw dry distillation fluid> Carbon ash. In addition, soil pH after improving showed an increased trend along with improver amount arising except straw dry distillation fluid. When we used the medium amount (processes 3) straw dry distillation fluid to acidic tea garden soil with pH4.11 and pH4.60, tea garden soil pH after improvement displayed a maximum value. Using improvers had an effect on tea garden soil properties such as soil exchange properties including exchangeable Al, exchangeable acid, exchangeable base cations, total exchangeable bases and exchangeable base saturation and soil organic matter content.Finally,4 kinds of improvers including biological carbon ash, ect. were selected to modify tea garden soil with moderate acidification. Results showed that improvers using in acidic tea garden soil could enhance soil pH, reduce soil exchangeable acid and exchangeable Al content, increase soil exchangeable base cations, exchangeable base saturation and soil organic matter content. Different modifiers had a different effect on acidic tea garden soil.