有机物料在紫色母岩风化碎屑中的腐解及调控

通过对3种常见的有机物料在两种紫色母岩新风化碎屑中的腐解规律研究。结果表明,在进行秸杆还田时,秸秆的种类、土壤水分含量,以及地表的覆盖条件都与秸秆的分解速率有很大关系。其中试验所采用的玉米秸秆、麦秆和牛粪三者中,玉米秸秆分解最快,牛粪最慢;土壤水分为16%-20%时,玉米秸秆分解速率最快,土壤水分过高或过低分解率都会降低。改善土壤的水热状况,以覆盖地膜或秸杆覆盖都能加快还田秸秆的分解速率,就二者来说,则以覆盖地膜效果更好。要想使三峡库区万县移民安置区居仙镇新垦紫色土壤中10年后有机质达20g/kg,根据Jenny模型计算,估计须每hm^2耕地每年返还38.2t干重玉米秸秆。

DECAY OF ORGANIC MATERIALS IN NEWLY - WEATHERED PURPLE ROCK FRAGMENTS AND ITS ADJUSTMENT

An experiment was conducted to study the decomposition of three organic materials,i.e.corn straw,wheat straw and cow dung,in two kinds of newly weathered purple rock fragments.The decomposition rate of the organic materials in the practice of "returning the harvested straw to the land" was found to be closely associated with soil moisture and mantling and vary with the kind of mulching material.Of the three organic materials investigated,corn straw decayed fastest while cow dung decomposed most slowly.The optimum soil moisture for corn straw decomposition ranged from 16% to 20%.Improvement in soil moisture and heat conditions,especially the former,accelerated the process of organic matter decomposition.An estimation based on Jenny model calculation revealed that 38.2 t/hm 2 of dry corn straw should be returned to the fields each year if the organic matter (OM) in the newly reclaimed purple soil is to be raised to 20 g/kg soil after ten years' cultivation in the resident-relocating areas in Wanxian city,which is located in the Three-Gorges Reservoir Area.