The Soil Effects Of Tea Garden Clippings And Their Biochars

As an important tea garden management, pruning has been used commonly in every process of tea garden development. In tea garden ecosystem, garden clippings and withered leaves fall together, forming a litter layer, they have a profound effect on soil environment. In the present study, a series of simulation trials had been conducted to find out the effects and mechanism of tea garden clippings return on soil. A new method of making biochar by tea garden clippings as a kind of acid soil conditioning has been present for widen the view of improving tea garden soil acidification and providing a reference for tea production. The major results obtained were summarized as follows:1Through incubation with quartz sand, the change of soluble aluminum content and pH were observed under the decomposition of pruned tea leaves. During the incubation, leaves decomposed fast at early, the pH of tea leaf extract increased1.84during the first2weeks; and then the speed slows down gradually, the mean value of pH remains7.09pH from14-35days. The trend of chang of soluble aluminum is opposite at the same time. The results show that ionic form of soluble aluminum changed during the decomposition of tea leaf. So we can know that, though the aluminum content is rich in tea leaves, it is not the reason of soil aluminium toxicity.2The effects of tea leaves on the acidity and some other relative properties of wasteland soil and tea garden soil were studied during indoor incubation at the rate of5,10and20g/kg added. The results reveal that adding at different levels decreased soil pH0.30、0.47、0.55(P<0.05) respectively in wasteland soil which has a higher initial pH. Oppositely, pH was increased0.15,0.27and0.38(P<0.05) correspondingly in different treatment of tea garden soil which has a lower pH. Besides, under application of5,10and20g/kg, the content of organic matter and soil available K in soil also increased with the increase of tea leaves. Hydrolysis ionizing out by organic acids of tea leaves neutralized with OH-is the most important reason for wasteland soil pH decreased rapidly. But acidizing is temporary, pH of each treatment has a trend of rise with the experiment goes on. For tea garden soil, organic salts of tea leaves play an important role in pH increasing, besides, decarboxylation of organic acid radicals in the decomposition process is helpful.3Two kinds of soils were chosen to investigate the effect of tea leaves on pH and migration of base cations with leaching experiment. After24weeks of leaching, the pH of different wasteland soil layers with tea leaves were lower1.27,1.38and0.99units than CK from upper to lower, tea garden soil layers are lower0.82,0.10and0.21units correspondingly. Besides, the content of exchangeable acid and exchangeable aluminium were increased respectively, and the increase of surface layer was the most significant (P<0.01). About the content of base cations, adding tea leaves has different effects on on2kinds of soils:in wasteland soil, the base ions content of adding treatments are lower than control respectively at the end of the experiment. But in tea garden soil, it is different.It reveals that under the leaching condition, acidification of soil by tea leaves not always goes with decrease of base ions.4the result of soil culture experiment showed that there is a significant difference between the amelioration effects of raw materials, biochar and maturity made from tea garden clippings. Biochar had the best amelioration effect on acidified tea garden soil. Tea garden clippings-based-biochar increased soil pH1.03-1.22units over the control at the rate of20g·kg-1.This result kept stable during the80days culture. Second, adding of biochar also enhanced carbon sequestration capacity for soils and the reduction in the release of carbon to the atmosphere.Besides, The incorporation of clipping-based biochar resulted in the increasing of exchangeable bases and the base saturation, decreasing exchangeable acid and exchangeable Al at the same time. In a word, returning as tea garden clippings-based-biochar is a worthily spreading method for tea garden clippings treatment.In conclusion, as an artificial ecological system, the imbalance of nutrient cycling in tea garden caused by harvest and management measures such as plowing usually lead to soil acidification and degradation. And this goes agaist the sustainable tea production. Under the indoor culture experiment condition, decomposition process reduced the acidity of tea leaves, enhanced adsorption and complexation effects, released mineral nutrients, showed good potential of improving acidification tea garden soil. But under the raining condition, leaching has the profound influence on the decomposition and transformation of tea leaves. Therefore, tea leaves adding into soil had rapidly accelerated the process of soil acidification in leaching experiement. Returning after treatment is not only establish a good nutrient cycling process, but also avoid the bad soil environment effects of returning directly.It has the important significance for tea garden management. Compared with other different treatments, making tea garden clippings into biochar before returning has better effects than pile-fermenting or returning directly on amelioration acidulated soil.