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以江西省余江县不同种植年限的红壤性水稻土为对象,研究了土壤有机质、pH、阳离子交换量(CEC)、游离氧化铁含量和氧化铁活化度随时间变化趋势;选择耕种7、22和80年的土壤剖面,研究了游离氧化铁和无定形氧化铁在剖面不同层次的分布。结果表明,耕层(0～20cm)土壤有机质含量随着水稻种植年限的增加而增加,淹水种稻导致土壤pH升高,但主要发生在种稻的前7年,7～80年间土壤pH变化不大。土壤CEC随着种植年限的增加而增加,在17年达到最大,然后随种稻时间的进一步增加而减小。土壤游离氧化铁含量随种稻时间呈下降趋势,但种稻后土壤氧化铁的活化度高于母土旱地红壤。对7年和80年水稻土,表层土壤游离氧化铁的含量低于底层土壤,说明铁在剖面中存在淋溶迁移。7年和22年水稻土表层土壤无定形氧化铁含量高于底层土壤,但对80年水稻土,土壤无定形氧化铁随采样深度的增加而增加。
Taking red paddy soil with different planting years in Yujiang County, Jiangxi Province as an example, the changes of soil organic matter, pH, cation exchange capacity (CEC), free iron oxide content and iron oxide activation degree with time were studied. And 80 years of soil profile, the distribution of free iron oxide and amorphous iron oxide at different levels of the profile was studied. The results showed that the content of organic matter in topsoil (0-20 cm) increased with the increase of planting years of rice and flooding paddy increased the pH of soil, but mainly occurred in the first 7 years and the soil pH Has not changed much. Soil CEC increased with planting years, reaching the maximum in 17 years and then decreasing with the further increase of planting time. The content of free iron oxide in soil decreased with the time of planting rice, but the activity of iron oxide in the soil after planting was higher than that in the native soil. For paddy soils for 7 years and 80 years, the content of free iron oxide in the surface soil was lower than that in the bottom soil, indicating that there was leaching and migration of iron in the profile. At 7 years and 22 years, the content of amorphous iron oxide in the surface soil of paddy soil was higher than that of the bottom soil, but for 80 years paddy soil, the amount of amorphous iron oxide increased with the increase of sampling depth.