秸秆还田对西藏中部退化土壤环境的影响

在西藏中部风蚀严重地区研究了旱季不同秸秆还田方式对退化土壤环境的影响以及土壤物理、化学(养分)和生物因子间的相互关系。初步结果表明,留高茬和秸秆覆盖方式对保护耕层土壤环境、降低土壤容重、提高土壤孔隙度、促进土壤团粒结构形成具有较大作用;对土壤水分、土壤温度、土壤有机质及土壤养分以及土壤微生物类群及其数量构成具有重要影响。还田期内,土壤物理、化学(养分)和生物因子间的相互影响和共同作用使退化土壤呈现出较为明显的恢复态势。秸秆翻埋的土壤含水量及环境综合效应则相对较低,充分反映了西藏中部秸秆翻埋的水分限制作用。土壤细菌在土壤微生物数量构成中占绝对优势。石灰性土壤条件下,土壤速效磷含量处于较高水平并与土壤pH呈正相关。

Effect of straw returning on the environment of degenerated soil in central Tibet

Effect of different methods of spring barley straw returning in dry se ason on soil environments and relation to soil physico-chemical properties and b iological factor of degenerated soil were studied in wind erosion district of ce ntral Tibet. Preliminary results showed that there was marked effect of higher s tubble and soil covered with straw could protect the soil environment of arable layer, reduce the bulk density, and improve the porosity, water-stable aggregat e , increase organic matter and soil nutrient contents, amount of soil microbes un der the ecological conditions of the central Tibet, and regenerated soil present ed a distinct improvement under the affected of physico-chemical properties and biological factor during the straw returning period. However, the comprehensive effect and soil water content was relative lower under incorporation of straw in dicated that soil moisture was a key factor that impair the effectiveness of str aw returning under the arid region and semiarid region in Tibet. The amount of b acterium account for overwhelming majority of the soil microbes under the differ ent methods of straw returning and it made a greater contribution to soil nutrit ion. In calcareous soil the content of the rapidly available phosphorus had high er level and it increased significantly by the increase of the pH.