玉米不同育苗方式下土壤团聚体及颗粒分形特征

稳定的土壤团聚结构对种子发芽、根系发育、作物生长以及有机碳保护有着重要的影响。农业管理措施对团聚体胶结剂质量和保存时间影响较大,必然影响土壤团聚体的形成和稳定,不同耕作和育苗方式作为重要的农业管理措施也必将对土壤团聚作用产生影响。选择玉米平作和垄作条件下6种育苗方式的土壤为供试材料,采用标准化平均质量直径和分形理论,探讨了土壤团聚体的稳定性、分形特征及二者之间的关系。结果表明,平作和垄作条件下6种育苗方式对土壤团聚体的稳定性影响不同,平作方式下,秸秆钵直播、包衣直播和垄作方式下,肥团育苗、秸秆钵育苗更有利于大于0.25 mm粒径较大团聚体的形成,对土壤形成稳定的结构具有积极意义;土壤团粒的分形维数与小于0.25 mm粒径含量呈极显著正相关,与0.5～1 mm、1～2 mm粒径含量呈极显著负相关,说明土壤团粒的分形维数越小,土壤团聚体稳定性越强。研究结果说明土壤团聚体的分形维数可以客观地表征土壤结构的稳定性,可以作为表征土壤结构和性质的重要参数,对于深入探讨分形学在土壤综合评价中具有重要意义。

Soil Aggregates and Fractal Features of Corn Field under Different Seedling Raising Styles

Stable structure of soil aggre gates is useful,which has important effect on seed germination,root development,crop growth and organic carbon protection.Agricultural management measures affect greatly quality of aggregates cementing agent and it's save time.Meanwhile,farming and seedling way as important agricultural management measures would greatly affect properties of soil aggregates.Choosing soil of 6 seedling ways under flat tillage and ridge tillage as researching materials,by the use of normal mean mass diameter and fractal theory,the stability of soil aggregates and the fractal characteristics as well as between both relationships was discussed.The results showed that the stability of soil aggregates was different.It was helpful to form aggregates with diameter than 0.25 mm under straw pot direct seedling,seed-coating of flat tillage and fertilizer cluster seedling,straw pot seedling of ridge tillage.These ways were positive to form stable soil structure.Fractal dimension had a significant linear positive correlation to the content of soil aggregates size <0.25 mm,on the contrary of the content of soil aggregates size of 0.5-1 mm and 1-2 mm.In the other word,the smaller soil particle fractal dimension was,the better stability of soil aggregates was.According to the results,soil particle fractal dimension could not only objectively characterize stability of soil structure,but also be used as an indicator of soil structure and properties.On the other hand,it had great significance to discuss Soil comprehensive evaluation.