Effect Of Long-term Application Of Scale Farm Animal Manure On Soil Properties Of The Tea Garden And Safety Analsysis For Agricultural Application Of The Manure

With the rapid development of large-scale farm industry in China in the past 30 years, large amounts of animal manure were generated. Land treatment is currently one of the best ways to resolve the problems brought by it. Animal manure is a traditional organic fertilizer for tea production and now it is recommended to be applied to non-pollution and organic tea gardens. However, as the widely use of feed addictive, the chemical compositions of the animal manure from large-scale farms have been changed. Generally, the manure producred from large-scale farm industry contains high concentrations of copper, zinc, soluble salts and soluble organic matter. For safety of agricultural food and preservation of environments, further studies are needed to reveal the effect of long-term animal manure application on the accumulation of heavy metals in tea garden soil and tea plants. In addition, the risk of heavy metal accumulation in tea garden soil is greater than other soils, because of its low pH. It is concerned whether the activity of heavy metals will be increased or decreased after long-term animal manure application.This experiment chose two of tea garden soils in Hangzhou city, Zhejiang province to study effects of long-term application of pig manure on fertility index, heavy metals accumulation and their bioavailability in the tea garden soils. The main conclusions are summarized as follows:(1). Application of pig manure can increased soil pH value, and the pH value of the incubated soils increased with application rates of the manure. The pH value of the soils decreased with increasing incubation time. However, the pH value of the soil incybated with pig manure was always higher than their control soil.(2). Application of pig manure also increased significantly soil nutrients, such as organic matter, alkali-hydro nitrogen, available P, K, Ca and Mg. The increases in soil nutrients increased with increasing application rate of pig manure. The concentrations of available nutrients in soil in 60th d were more than those in 30th d, which indicated that levels of available nutrients in the soils incubated with pig manure increased with time. (3). Application of pig manure with high concentrations of copper and high-zinc increased content of all different forms of Cu and Zn in soils, and the proportion of different forms of the metals in the soils decreased in the sequence of reducible> acid extractable> oxidizable> residual.(4). Application of pig manure or tea-leaf could decrease available Pb and Cd in the soils, and the effects increased with increasing application rate of pig manure or lea-leaf. For soils incubated with pig manure and tea-leaf, available Pb reduced and available Cd increased with increasing incubation time. However, available Pb and Cd in the soils incubated with organic materials were always lower than their control soils.(5).The safety application of animal manure in tea production was also discussed in the paper. Based on concentrations of heavy metals in animal manure collected from Zhejiang province, the safety amounts of animal manure were calculated. The suggested annual application rate of animal manure for tea production was 306 kg/ha, 2587 kg/ha, and 45404 kg/ha per year, respectively, for animal manure with high, middle, and low cncentrations of heavy metals.