Soil Properties And Plant Al Status In Tea Gardens Of Different Ages Within A Hilly Red Soil Farm

In order to understand the relationship between soil properties and plant Al status in tea gardens of different ages within a hilly red soil farm, we collected samples at depths of 0-20 cm and 20-40 cm from Nanchang city Huangma county. Typical tea gardens with different planting years were chosen (wasteland,10 years,10-20 years, 20-30 years,30-40 years,40-50 years,50 years) as research objects. By these researches, we can learn soil basic chemical properties of tea garden with different depths (0-20 cm and 20-40 cm), soil properties in red hilly soils and plant Al status in tea. On these issues, operating history of tea gardens and the impact of the safety of Al in tea can be discussed. The main results are as follows.(1) The pH value, caption exchange capacity, organic C, total N and total P content (P<0.05) in tea garden were significantly affected by planting years. Comparing soils from tea plantations of different ages, we observed increasing levels of caption exchange capacity, organic C, total N and total P content with planting time, but the pH value decreasing.(2) All soil fractions and total Al showed an increasing tendency with increasing planting year at 0-20 cm,20-40 cm and 0-40 cm depths, respectively. Different depths correlated significantly with the content of various forms of Al (P<0.05). K.CI-Al, CuCl2-Al and NH4AC-Al accounted for low percentage of extractable Al, but HCI-Al and NaOH-Al accounted for larger proportion, both of them are larger than 70 percentage of extractable Al.(3) The soil pH value, caption exchange capacity and organic C were the main factors which affect Al content in tea garden soil. The pH value negatively correlated with KC1-Al and CuCl2-Al, while caption exchange capacity and organic C positively correlated with KC1-Al and NH,AC-Al. Soil pH was identified as a major factor that control the uptake of Al from soil into the tea leaves. (4) In tea plants Al mainly accumulated in mature leaves, and their Al content increased with the extension of planting years. The distribution order of labile Al in tea plant is generally old leaves> roots> mature leaves> old stems> new stems.(5) By correlation analysis among soil Al fractions and plant Al status showed that, Soil KC1-Al generally correlated with Al in roots, old stems, new stems and old leaves, but it negatively correlated with CuCl2-Al, NH4AC-Al, HCI-Al and NaOH-Al. KC1-Al was identified the main effectively forms that can be absorbed and used by tea plant. In general, soil basic chemical properties changed, soil Al fractions and plant Al status showed an increasing tendency with increasing planting year. The biogeochemical cycles in tea garden farm continuously strengthened and accelerated. The research of biogeochemical cycles in tea garden farm and the safety of Al in tea need to be further.