潮土中磷锌交互作用机制探讨及磷对锌吸附-解吸的影响

The mechanism of phosphorus and zinc interaction and the effects of phosphorus on zinc adsorption & desorption in Chao soil

采用室内培养和吸附解吸两种方法,探讨了潮土中磷、锌交互作用机制。结果表明：土壤中DTPA提取态锌质量分数随添加锌量的增加而增加,低磷质量分数处理可提高土壤锌有效性,但高磷质量分数处理却降低了土壤锌的有效性;土壤速效磷质量分数均随锌添加量的增加而有所降低。在施锌25 mg.kg-1背景下,土壤中DTPA提取态锌质量分数随施磷质量分数的增加呈先增加后降低趋势,在添加磷量小于180 mg.kg-1时,土壤DTPA提取态锌质量分数显著地高于其他处理,但随添加磷量的增加,土壤DTPA提取态锌质量分数显著降低,当磷添加量大于540 mg.kg-1时,土壤DTPA提取态锌质量分数明显低于其他磷处理,说明当添加磷量小于180 mg.kg-1时,磷提高土壤中锌有效性的主要机制是二者竞争吸附土壤胶体表面吸附点位的竞争机制;当添加磷量大小540 mg.kg-1时,磷影响锌有效性的主要机制为沉淀作用。在土壤施磷量为180 mg.kg-1时,随添加锌质量分数的提高,土壤中速效磷质量分数呈先升高后降低趋势。吸附-解吸研究表明,随土壤中速效磷质量分数的提高（27.60~2773.86 mg.kg-1）,土壤对锌的吸附量先降低再增加,而KCl解吸的锌量却是先增加再降低。因此潮土中磷锌交互作用机制为,土壤中磷和锌质量分数均较低时,磷与锌有效性呈协同作用;当磷或锌质量分数过高时,协同作用减弱;磷和锌质量分数再增加二者的有效性将出现拮抗作用。

The mechanism of phosphorus and zinc interaction in Chao soil was investigated by incubated and adsorption and desorption method.The results showed that,the soil DTPA-Zn content was increased with added Zn content increased,the treatment of low content P could improve soil Zn availability,while the treatment of high content P reduced Zn availability.The available P content was decreased with added Zn content increased.Under P content of 25 mg.kg-1 treatment,the soil DTPA-Zn content was increased at first and then decreased with added P content increased,when P content was less than 180 mg.kg-1,the DTPA-Zn content was significantly higher than that of other treatment,and the DTPA-Zn content was significantly reduced with P content increased,when P content was higher than 540 mg.kg-1,the DTPA-Zn content was significantly less than that of other P content treatment,it could explain that when P content was less than 180 mg.kg-1,the mechanism of P increase the Zn availability was both of them competition the soil colloid absorbable position,while when P content was higher than 540 mg.kg-1,the mechanism of P affect the Zn availability main was deposit reaction.Under P content of 180 mg.kg-1 treatment,the available P content was increased at first and then decreased with Zn content increased.The adsorption desorption experiment indicated that the Zn adsorbed amount was decreased at first and then increased,while Zn desorbed amount by KCl was increased at first and then decreased with soil available P increased（27.60-2 773.86 mg.kg-1）.So,the mechanism of P Zn in Chao soil was： when the P and Zn content was very low,the availability of P and Zn was synergistic effect,while when P and Zn content was higher,the synergistic effect would weakened,and P and Zn content was more increased,the availability of P and Zn would was antagonism effect.