酸化对水稻土钾素形态及淋移性的影响

Effects of Acidification on Forms and Leaching of Potassium in Paddy Soils

为了解土壤酸化对水稻土钾素平衡的影响,在浙江省选择4种代表性土壤,模拟土壤酸化,并在酸化土壤中采用施用钾肥等措施,研究其对土壤钾形态转变的影响。结果表明,随着土壤酸度的增加,土壤钾素形态发生了明显的变化,逐渐由矿物态、非交换态向交换态和水溶态转变;矿物态和非交换态的比例逐渐下降,而水溶态的比例逐渐增加。土壤中矿物态钾和非交换态钾发生明显下降的pH值大约为3.0~4.5;酸化对滨海平原和水网平原水稻土中矿物态钾和非交换态钾的影响大于对丘陵和河谷平原水稻土的影响;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。淋洗试验表明,酸化加速了土壤钾素的释放和迁移,释放量随土壤酸度增加而上升;在酸性土壤中施用沸石可增强土壤对钾素转变的缓冲性,降低土壤钾素的淋失。

In order to understand the effect of acidification on potassium balance in paddy soil,four representative soils in Zhejiang Province were selected to study the effects of simulated soil acidification and application of potassium fertilizer on the forms and leaching of potassium in acidified soils.The results showed that with the increase of soil acidity,forms of potassium in the soils changed significantly,and gradually transformed from mineral-bound and non exchangeable into exchangeable and water-soluble forms.The proportion of mineral-bound and non exchangeable forms decreased,while the proportion of water-soluble form increased.The pH values in which the proportion of mineral-bound and non exchangeable potassium decreased significantly were about 3.0~4.5.The effects of acidification on mineral-bound and non exchangeable potassium in the paddy soils from the coastal plain and water network plain were greater than those of hilly and valley plain.After soil acidification,the potassium added into the soils mainly existed in water-soluble and exchangeable forms with high activity,and the conversion proportion of the added potassium into non exchangeable form became less,and the buffer capacity of the soils for exogenous potassium decreased gradually.Leaching experiment showed that the acidification accelerated the release and migration of potassium in the soils,and the release increased with the increase of soil acidity.The application of zeolite in acid soil could enhance the buffering ability of soil to potassium transformation and reduce the leaching loss of potassium.