内-外源有机质对黑土磷素吸附及有效性的影响

Effect of Endogenous and Exogenous Organic Matter on Phosphorus Adsorption and Availability in Black Soil

为探究有机质对东北黑土磷(P)吸附及有效性的影响,选用高有机质黑土(T1)、中有机质黑土(T2)、低有机质黑土(T3)3种不同有机质水平黑土,通过去除有机质操作探讨磷吸附-解吸是否受内源有机质影响。并选用高有机质黑土为材料,设置有机肥添加量分别为0%(CK)、1%(C1)、2%(C2)、3%(C3)共4个处理,分析不同有机肥添加量对土壤理化性质及磷有效性的影响。结果表明,随着有机质含量的提高,黑土吸附亲和力常数(K)、最大吸附量(qm)、土壤最大缓冲量上升,土壤磷饱和度(soil phosphorus saturation,DPS)降低,表明磷在有机质高的土壤中不易流失。有机质含量越高,土壤对磷吸附能力越强,当平衡含量为100 mg·L^(−1)时,T1、T2、T3处理土壤磷吸附量分别为754.83、722.58、660.65 mg·kg^(−1)。有机质含量越低,土壤对磷解吸能力越强,磷有效性越强。去除有机质操作使不同水平有机质含量黑土磷吸附量下降5.90%~17.33%,增强了土壤磷有效性。对于磷等温吸附方程决定系数(R2),Langmuir方程大于Freundlich方程,拟合程度较好;土壤磷吸附主要由化学吸附主导。不同剂量有机肥施加均可以降低黑土对磷的吸附速率,且随有机肥添加量增加,吸附速率显著降低。当达到最大磷平衡含量时,C3处理土壤磷吸附量降低程度最大,土壤磷有效性最强,准二级动力学方程能较好地表达有机肥对土壤磷吸附动力学特征。添加有机肥使土壤pH、速效磷、有效磷和酸性磷酸酶活性分别显著增加1.05%~3.97%、121.43%~251.35%、8.38%~12.65%和42.96%~57.77%。研究结果为科学管理不同区域黑土、合理施用有机肥、提高磷素的有效性提供科学支撑。

In order to explore the effect of organic matter on phosphorus(P)adsorption and availability in northeast black soil,3 types of black soil with different levels of organic matter including high organic matter black soil(T1),medium organic matter black soil(T2)and low organic matter black soil(T3)were selected to explore whether the adsorption-desorption of phosphorus was influenced by endogenous organic matter by removing the organic matter.In addition,black soil with high organic matter was selected as the material,and 4 treatments with different organic fertilizer addition rates were set,including 0%(CK),1%(C1),2%(C2),3%(C3),respectively.The effects of different organic fertilizer addition rates on soil physicochemical properties and phosphorus availability were analyzed.The results showed that with the increase of organic matter,the black soil adsorption affinity constant(K),maximum adsorption capacity(qm),and soil maximum buffer content increased,while the soil phosphorus saturation(DPS)decreased,indicating that phosphorus was less likely to be lost in soils with high organic matter.The higher the organic matter,the stronger the soil’s ability to adsorb phosphorus.When the equilibrium content was 100 mg·L^(−1),the phosphorus adsorption capacities of T1,T2 and T3 treatments were 754.83,722.58 and 660.65 mg·kg^(−1),respectively.The lower the organic matter,the stronger the soil’s ability to desorb phosphorus,and the higher the phosphorus availability.Removing organic matter reduced the phosphorus adsorption capacity of black soil with different levels of organic matter by 5.90%to 17.33%,enhancing soil phosphorus availability.The determination coefficient(R2)of the phosphorus isothermal adsorption equation was higher for the Langmuir equation than for the Freundlich equation,indicating a better fit;soil phosphorus adsorption was mainly dominated by chemical adsorption.Different doses of organic fertilizer application could reduce the adsorption rate of phosphorus by black soil,and the adsorption rate significantly decreased with the increase of organic fertilizer dosage.When the maximum phosphorus equilibrium concentration was reached,the C3 treatment had the greatest reduction in soil phosphorus adsorption and the highest soil phosphorus availability.The pseudo-second-order kinetic equation could well express the kinetic characteristics of soil phosphorus adsorption with organic fertilizer application.The addition of organic fertilizer significantly increased soil pH,available phosphorus,effective phosphorus and acid phosphatase activity by 1.05%~3.97%,121.43%~251.35%,8.38%~12.65%and 42.96%~57.77%,respectively.Above results provided scientific theoretical support for scientific management of black soil in different regions,rational application of organic fertilizer and improvement of phosphorus availability.