酸化对茶园土壤矿物转变及供钾能力的影响

酸化是种植茶树后土壤变化的普遍现象。为了解酸化对茶园土壤矿质组分和钾素的长期影响，选择花岗岩发育的红壤茶园为研究对象，以相邻林地为对照，采用实地采样分析与模拟试验相结合的方法，研究长期种植茶树20 a和50 a后土壤酸化导致的土壤矿物和土壤钾素形态的变化，以及酸化对外源钾肥在土壤中钾形态转变的影响。结果表明，茶园土壤酸化降低了土壤缓效性钾的容量，减少了砂粒和粉粒中云母、长石等含钾矿物含量，促进了土壤黏粒中2∶1型（伊利石）矿物向1∶1型矿物（高岭石）的转变，降低了土壤总钾量。随着土壤酸度的增加，土壤中矿物态钾和缓效钾的比例逐渐下降，水溶态钾的比例逐渐增加。土壤酸化后，施入土壤中的钾主要以活性较高的水溶态和交换态存在，向非交换态转化的比例明显降低，土壤对外源钾的缓冲性逐渐下降。在酸性土壤中施用沸石可增强土壤对钾素形态转变的缓冲性。研究认为，茶园土壤酸化可显著降低土壤总钾量，减弱土壤供钾能力及对肥料钾的缓冲能力。

Effects of Acidification on Mineral Transformation and Potassium Supply Capacity of Tea Garden Soils

Acidification is a common phenomenon of tea garden soils. In order to understand the long-term effects of acidification on mineral components and potassium in tea garden soils, the red soil developed from granite was selected, and the forest land of the same soil type was used as the control. Through soil analysis and simulation experiments, the changes and differences of soil minerals and soil potassium forms caused by soil acidification were compared after 20 and 50 years of continuous planting of tea trees. The results show that the acidification of tea garden soils reduced the capacity of slow available potassium and potassium containing minerals such as mica and feldspar in sand and silt fractions, promoted the transformation from 2∶1 type (Illite) minerals to 1∶1 type minerals (Kaolinite) in clay fraction, and reduced the total potassium content of the soils. With the increase of soil acidity, the proportion of mineral bound form and non-exchangeable form K in the soils decreased gradually. While the proportion of water-soluble K increased gradually. After soil acidification, the potassium applied to the soils mainly existed in water-soluble and exchangeable forms with high activity. The proportion of K in non-exchangeable form was significantly reduced, and the buffering ability of soil to external source K was gradually reduced. The application of zeolite in acidic soils could enhance the buffering ability of the soils to potassium transformation and reduce the leaching loss risk of soil potassium. The results show that soil acidification in tea gardens could significantly reduce soil potassium, weaken soil potassium supply capacity and potassium buffering ability.