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对稻草、紫云英有机物料不同用量和混施、单施或沤制后施用等不同施用方式对土壤结构的影响进行了四年模拟试验。四年培育期中的水分条件和其他物理条件均控制一致。测定表明,有机物料能明显改善土壤的结构性和孔隙性,降低原状土核的破裂系数。有机质、重组有机质、无定形氧化铁、氧化铁的活度与团聚体的稳定性呈正相关;而与原状土的破裂系数呈负相关。看来,无定形氧化铁的含量可以作为高产水稻土具有良好结构性的一个间接指标。施加有机物料的土壤,当脱水时其中大孔隙显著增多,这对粘质水稻土回旱种旱作十分有利。稻草直接施入土中的改土效果优于沤制后施入土中,且不亚于高用量稻草和紫云英混施的效果。可见,如绿肥施用量减少时,只要保持一定量的稻草回田,亦能改善土壤的结构。
The effects of different application methods, such as straw, Astragalus mongholicus, organic manure on the soil structure, were studied in four years. Four-year incubation period of water conditions and other physical conditions are controlled. The results show that the organic material can obviously improve the structure and porosity of the soil and reduce the rupture coefficient of the undisturbed soil core. The activities of organic matter, recombinant organic matter, amorphous iron oxide and iron oxide are positively correlated with the stability of aggregates, but negatively correlated with the rupture coefficient of undisturbed soil. It appears that the amount of amorphous iron oxide can serve as an indirect indicator of the good structural properties of high-yield paddy soils. The organic matter-applied soil, when dehydrated, had a significant increase in macroporosity, which was very favorable for the dry-farming of clayey paddy soils. Straw soil directly applied to the soil improvement effect is better than the system and applied to the soil, and no less than the high amount of straw and milk vetch mixed effect. This shows that when the amount of green manure applied is reduced, as long as a certain amount of straw is returned to the fields, the soil structure can also be improved.