基于CT技术的稻田不同轮作方式下土壤孔隙结构研究

CT Technique to Analyze Pore Structures of Paddy Soils under Different Rotations

合理的轮作种植制度是改善土壤结构及有效利用土壤水分的重要方式之一。本研究以广西稻田为研究对象,在水稻-油菜轮作和双季稻处理条件下,利用CT扫描原状土柱,结合Image J软件及其插件计算获得土壤孔隙数量、弯曲度和孔隙连通性等孔隙结构特征参数并进行土壤结构三维重建。结果表明:轮作区的孔隙面密度大于双季稻区,孔隙度和孔隙数量均值(0.457%,451个)大于双季稻区(0.345%,358个),弯曲度及连通性(1.332,0.474)也大于双季稻区(1.272,0.217),但两者的水力半径没有明显差异。水旱轮作由于减少了土壤淹水时间,改善了土壤胶结状态,促进了作物根系生长和延伸,导致孔隙结构发育更好,导水性更强,是促进水稻田土壤结构改善和水分运移的倡导模式。

Appropriate rotation system is one of the important ways to improve soil structure and utilization efficiency of soil water. Paddy soils under rice-rape rotation and rice-rice rotation in Guilin of Guangxi were taken as the study objects. The undisturbed soil columns （10 cm diameter x 30 cm depth） were scanned with CT. And then the parameters of soil pore structure characteristic such ImageJ software and its plugins and the pore 3D as soil pore number, tortuosity reconstruction was performed. and connectivity were calculated by The results showed that the pore surface density under rice-raperotation was greater than that under rice-ricerotation. The mean values of porosity and pore number under rice-ricerotation（0.457%, 451） were also greater than those under rice-rice rotation （0.345%, 358）. In addition, the mean tortuosity and connectivity under rice-rape rotation （1.332, 0.474） were greater than those under rice-rice rotation （1.272, 0.217）, but there was no significant difference in the hydraulic radius between rice-rice rotation and rice-rice rotation. It suggested that paddy-upland rotation could reduce the period of soil submergence and increase hydraulic conductivity,which would improve the cementing status of soil and promote the growth and extension of crop root. Such rotation isrecommended as an effective management inimproving soil structure and water movement in the local region.