稻作制度对红壤性水稻土有机质特征的影响

采用长期定位试验,比较3种稻作制度对红壤性水稻土有机质总量、有机无机复合状况、腐殖质结合形态、腐殖质组成、胡敏酸光学性质和总酸度等的影响。结果表明:冬泡制度比水旱轮作有助于增加土壤有机质总量、重组有机质含量、胡敏酸含量和胡敏酸/富啡酸,而水旱轮作比冬泡制度有利于提高土壤松结合态腐殖质、松结合态腐殖质/紧结合态腐殖质、胡敏酸E4值和总酸度。由此说明,冬泡制度有利于土壤有机质总量和胡敏酸的累积,但不利于胡敏酸分子的增长,腐殖质品质较差。而水旱轮作条件下土壤有机质活性增加,胡敏酸分子结构趋于复杂,其氧化度和芳香度增加。因此,通过周期性的水旱轮作换茬,可使土壤有机质的腐殖化和矿质化过程比例协调,从而提高土壤有机质的质量。

Effect of Rice-Based Cropping Systems on Organic Matter Properties in Paddy Soil Derived from Red Earth

A long-term stationary experiment was conducted to investigate effects of three rice-based cropping systems on total organic matter content, status of organo-mineral complexes, form and composition of humus, optical properties and acidity of HA in paddy soil derived from red earth. Results showed that the system of rice-rice-flooded fallow was higher than the paddy-upland alternation system in contents of total organic matter, heavy fraction organic matter, and HA and HA/FA ratio, but it was reverse in loosely combined humus content, ratio of loosely to tightly combined humus, E4 value and total acidity of HA contrary. In conclusion, the former contributed to accumulation of total organic matter and HA, but not to growth of HA molecules and quality of humus, while the latter did to activity of soil organic matter, complexity of molecular structure of HA, oxidation degree and aromaticity of HA, suggesting that harmonization between the humification and mineralization of soil organic matter through regular alternation of paddy and upland cropping can improve quality of soil organic matter.