保护性耕作对潮土结构特性的影响

研究不同保护性耕作措施对潮土结构特性的影响,探求不同秸秆还田方式下土壤结构的变化规律.以河北省石家庄市栾城县长期定位试验为研究基础,采用了传统翻耕、翻耕秸秆还田、旋耕秸秆还田、免耕覆盖还田、免耕立秆还田和免耕粉碎还田6种处理,分别对不同耕层的土壤容重、有机碳含量、团聚体及有机无机复合体进行了测定,对比分析了不同保护性耕作对潮土结构特性的影响.结果表明:免耕覆盖还田的土壤容重值最低;干筛情况下,免耕秸秆覆盖还田的MWD值显著高于其它处理30.4%～47.4%,而湿筛情况下,免耕立秆还田与粉碎还田MWD值高于其它处理;立秆还田的土壤分散系数最低,而粉碎还田的分散系数比其它处理高20.48%～330.93%;翻耕处理的原土复合量、原土复合度分别高于免耕处理10.82%～21.62%、8.97%～20.97%.不同秸秆还田方式对土壤结构稳定性的影响有很大差异:覆盖还田能改善田间土壤结构;立秆还田能提高微团聚体的稳定性;粉碎还田通过增加土壤有机碳含量而增加水稳性大团聚体的含量.

The effect of conservation tillage on the structural characteristics of Fluvo-aquic soil

The effect of different conservation tillage measurement on structural characteristics of Fluvo-aquic soil were studied, and the variation law of soil structure under different ways of straw returning were searched. This study is based on long field experi-ments of Luancheng country of Hebei province Shijiazhuang city, six treatments of tillage systems were utilized: conventional tillage、tillage with straw returning、rotary tillage with straw returning, no tillage with mulch, no tillage with standing stubble and no tillage with crush returning, soil bulk density, soil organic carbon content, aggregate and organo-mineral complexes were measured. The results showed: the lowest soil bulk density value is no tillage with mulch; the MWD value of no tillage with mulch significantly higher than other treatments 30.4%～47.4% in dry sieving, while the MWD value of no tillage with standing stubble and no tillage with crush returning is higher than other treatments in wet sieving; the lowest disperse coefficient is no tillage with standing stubble, while the disperse coefficient of no tillage with crush returning is higher than other treatments 20.48%～330.93%; the original soil complex amount、original soil complex degree of tillage treatment is higher than no tillage 10.82%～21.62%, 8.97%～20.97% respec-tively. The different ways of straw returning have a different influence on soil structure stability: no tillage with mulch can improve field soil structure; no tillage with standing stubble can advance the stability of microaggregate; no tillage with crush returning can increase the content of water stability macroaggregate through increasing soil organic carbon content.