Adsorption and desorption of dissolved organic matter （DOM）in soils

Chinese. 【目的】了解不同类型土壤对水溶性有机物的吸附和解吸差异,为有机肥的合理施用以及进一步研究其化学行为提供参考。【方法】选择普通肥熟旱耕人为土（黑土母质发育）、石灰肥熟旱耕人为土（褐土母质发育）和酸性肥熟旱耕人为土（第四纪红壤母质发育）3种理化性质差异较大的土壤,开展添加水溶性有机物（DOM）后不同吸附时间下土壤对DOM的吸附和解吸试验,并利用相关模型计算了土壤对DOM吸附和解吸的参数。【结果】外源DOM进入土壤后,能很快被土壤胶体吸附,并在1h内达到平衡;3种土壤对DOM的吸附差异明显,其达到平衡时的吸附量分别为10236、8372和10088mg・kg-1,即以有机质含量高的普通肥熟旱耕人为土和pH低的酸性肥熟旱耕人为土对DOM的吸附量大;3种土壤对所吸附DOM的解吸量比较,在吸附量达到最大时,解吸量占吸附量的比例分别为63.2%、42.1%和93.3%;3种土壤对所吸附DOM的解吸能力比较,亦为酸性肥熟旱耕人为土〉普通肥熟旱耕人为土〉石灰肥熟旱耕人为土。【结论】土壤性质与其对DOM的吸附和解吸密切相关,因此,不同类型土壤在有机肥施用量和施用方法上也需要相应进行改变。

English. [ Obiective ] The objective of this investigation was to compare the difference of adsorption/desorption of dissolved organic matter （DOM） in different types of soils, and to give guidance of correct application of organic fertilizer and further research on corresponding chemical behavior of DOM. [ Method ] Three kinds of soils including Typic Fimi-Orthic Anthrosols （black soils-- parent material）, Calcaric Fimi-Orthic Anthrosols （cinnamon soils-parent material） and Dystric Fimi-Orthic Anthrosols （quaternary red clay-parent material） with great difference each other were selected for studying the adsorption, desorption and fixation of DOM. Some parameters on adsorption/desorption of DOM in soils were calculated using corresponding model through the adsorption/desorption experiment under the condition of different amounts of DOM added into soils at various times. [ Result] The study indicated that DOM from external source could be adsorbed by soil colloid, and adsorption and desorption of DOM would reach the balance within one hour. There was a great difference in the adsorption of DOM among the three kinds of soils, and the greatest adsorped amount of DOM in Typic Fimi-Orthic Anthrosols, Calcaric Fimi-orthic Anthrosols and Dystric Fimi-orthic Anthrosols was 10 236, 8 372 and 10 088 mg・kg. 1, respectively, when the balance between adsorption and desorption appeared, suggesting the relatively higher amount by adsorption occurred in Typic Fimi-Orthic Anthrosols with relatively higher organic matter content and in Dystric Fimi-Orthic Anthrosols and relatively lower pH value. In comparison with the desorption ability of three kinds of soils, the decreasing order rank was Dystric Fimi-Orthic Anthrosols〉Typic Fimi-Orthic Anthrosols〉Calcaric Fimi-Orthic Anthrosols. [ Conclusion]There is a close relationship between the soil quality and DOM amount in soils through desorption/sorption process. Therefore, some changes in the application amount and methods of organic fertilizer are needed for different types of soils.