【摘要】 本文应用了原状土薄片及扫描电镜技术,观察了集约农作制下几种措施(模拟培育4年后)下的土壤结构的微形态特征。观察表明,施用有机物料明显增加粘质土壤的孔隙,不仅团聚体间有大孔隙,团聚体内也有中或细孔隙,彼此形成“交通网络”,有利通气排水。稻草直接施入土中同样能促进土壤团聚化和多级孔隙的发展,且孔隙壁上有极明显的铁质积聚,从而增强了“交通网络”的稳定性。粘闭使土壤颗粒紧密排列呈整块状结构,土体中孔隙极少,孔隙壁没有明显的铁质胶膜,但见到土体中有条状铁质浸染,它可能促进僵土块的形成。淹水时间长短对土壤结构微形态也有明显影响。在同样土壤质地和有机质水平下,同“一熟”淹水相比,“两熟”淹水促进土壤颗粒紧密排列,土壤孔隙,尤其是大孔隙明显减少。这种情况在有机质水平较低的土壤中更突出。更多还原

【Abstract】 Micromorphological characteristics of the soils under simulation of intensive cropping system for four years were investigated by means of the thin section and scanning electron microscopic techniques. The micromorphological observation showed that porosity of clayey soil increased with the organic materials applied in soil, in the soil applying organic material, not only the macropores occured among the aggregates, but the medium and micropores also exsisted in the aggregates, which formed a network of pathways beneficial for the movement of both air and water in soil This structure in soil consequently is also favorable for the field cultivation and sowing of upland crops after harvesting rice crop in intensive farming system. Directly applying rice straw in soil promoted soil aggregation and increased soil porosity. Under treatment of directly applying rice straw, iron coatings were formed on the wall of soil pores, which stabilizes the network of pathways in soil. Due to tight arrangement and formation of massive structure resulted from puddling, few soil pores and no iron coating on the wall of pores were observed in the thin section of the soil, Iron streaks, however, was found in the soil matrix. The morphology of soil. structure varied with different flooding, duration of soil. It is indicated that the flooding condition of soil under double cropping rice is a factor to result in the compaction and lack of pores in soils.更多还原