作物秸秆碳在土壤中分解和转化规律的研究

DECOMPOSITION AMD TRANSFORMATION OF 14~C-TRACED STRAW IN SOILS

采用^(14)C—标记秸秆,在大田和实验室的研究结果表明,秸秆的分解速率主要取决于C/N比。施入土壤后,土壤微生物迅速增加,尤其是细菌。秸秆降解首先形成非结构物质,其中大部分转化为富里酸,进而转化为胡敏酸。分解产物对土壤腐殖质的更新,从腐殖质表面官能团或分子断片开始,逐步进行。非结构物质可与腐殖酸的单个分子产生交联作用,在一定条件下,交联的复合分子可进入腐殖质分子核心的成分中。腐殖酸单个组分在土壤中的转化和重新分配,仅仅与腐殖质表面官能团的反交换过程密切相关。粘土矿物选择性吸附胡敏酸,而且优先吸附胡敏酸中低分子成分。

To study the decomposition and transferring rate of straw, the ^(14)C traced straw was used in labor and field experiments. The preliminary results are as follows:( 1 ) Decomposition rate of straw depends mainly on the C/N ratio. After straw applied into soil, the population of microorganism increases rapidly, especially bacteria.( 2 ) During its decomposition, the straw changes at first into the non-structure substances. Most of these non-structure substances transfers then into fulvic acfd and afterwards humic acid. The dico-mposed substances can renew soil humus. The procedure takes place at the functional groups of humus surface and the fraction of the molecules. The non-structure substance can cross link with a single humic acid molecule. Under certain conditions the cross-linked molecule can enter into the kernel of humus molecule. The transformation and re-distribution of the single component of humic acid in soil is only close related with exchange reaction of functional groups of humus.( 3 ) Clay minerals can adsorb humic acid selectively. Preference of this selective adsorption is given to the low molecule humic acids.