山西省主要耕地土壤对磷的吸附解吸特征

Phosphorus adsorption and desorption kinetic characteristics in main cultivated soil in Shanxi province

山西省主要耕作土壤对磷养分的吸附解吸特征鲜有报道。以山西省褐土、潮土和黄绵土三大主要耕作土壤为研究对象,对比分析了不同类型土壤对磷的吸附解吸过程及其特征参数。结果表明,3种不同土壤对磷的吸附量和解吸量均随外源磷浓度的增加而增加,吸附量随土壤深度增加而增大,但解吸量随深度增加而减小。3种土壤不同土层对磷的吸附过程均与Langmuir方程拟合良好,从等温吸附特征参数来看,土壤最大吸附量的最大值为793.65 mg/kg,出现在褐土40~60 cm土层中;土壤最大缓冲量以潮土0~20 cm土层最小,为16.31 mg/kg;而黄绵土40~60 cm土层K值最大,为0.494。3种土壤相同土层对磷的解吸量均表现为褐土>潮土>黄绵土。另外,褐土、潮土和黄绵土的需磷量分别为7.10、3.22和5.65 mg/kg。总之,褐土对磷有较强吸附能力,且吸附的磷易被解吸;潮土对磷吸附能力相对较弱,但供磷能力较强;黄绵土相较褐土与潮土对磷解吸能力较弱。在农作物种植过程中,需根据当地土壤对磷吸附解吸特性合理制定磷肥施用方案。

Phosphorus(P)adsorption and desorption in soil is an important internal cycle to solve soil fertility problems.In order to understand the adsorption-desorption process and mechanism of P in cinnamon soil,fluvo-aquic soil and yellow cultivated loessial soil which are the three major types of cultivated soils in Shanxi Province,exogenous P adsorption culture method was used to study the adsorption-desorption process of P in 0-60 cm layers of the three soil types,and the Langmuir isotherm adsorption equation was used to fit the P adsorption kinetics curve,which was used to explore the characteristics of soil P adsorption and desorption.The results showed that the amount of P adsorbed and desorbed in the soil increased with the increase of exogenous P concentration,and the amount of P adsorbed in the soil also increased with the increase of soil depth,but the amount of P desorbed was adverse in all three soil types.The adsorption process of P could be described by Langmuir isotherm adsorption equation well.The maximum adsorption capacity(Qm)was 793.65 mg/kg in 40-60 cm layer of cinnamon soil.The maximum buffering capacity(MBC)of 0-20 cm layer of fluvo-aquic soil was 16.31 mg/kg,and the maximum adsorption coefficient(K)was 0.494 in 40-60 cm layer of yellow cultivated loessial soil.The amount of desorption P was cinnamon soil>fluvo-aquic soil>yellow cultivated loessial soil in the same soil layer.Otherwise,the P requirement was 7.10,3.22 and 5.65 mg/kg in cinnamon soil,fluvo-aquic soil and yellow cultivated loessial soil,respectively.Above all,the P adsorption of cinnamon soil was larger and the more easily desorbed than that of fluvo-aquic soil and yellow cultivated loessial soil.Although P adsorption capacity of fluvo-aquic soil was weak,its P supply capacity was strong.The P adsorbed in yellow cultivated loessial soil was more difficult to be desorbed than the other two kinds of soil.In the process of crop planting,the application scheme of P fertilizer should be considered reasonably according to the characteristics of P adsorption and desorption in local soil.