Impact of Different Residue Retention System on Soybean Root Distribution in Soil Profile

Soybean root vertical distribution in soil profile under different residue retention system was studied in order to provide theoretical guidance for improving soybean root development environment.The experiment consisted of three treatments:NT(no-tillage),SCRR(Stubble cut off with residue retention),and CT(Conventional tillage).Root length,root surface area,root volume,and root dry weight distributed mostly in 0-10 cm soil depth.There were significant differences in root volume density and root dry weight density between different tillage treatments and the minimum values under NT in 0-10 cm depth.Not only root length density,root surface area density,root volume density,and root dry weight density but also root length percentage distribution,root surface area percentage distribution,root volume percentage distribution,and root dry weight percentage distribution were the lowest under NT in 10-20 cm depth.There were no significant differences between tillage treatments not only on root length density,root surface area,root volume density,and root dry weight density but also on root length percentage distribution,root surface area percentage distribution,root volume percentage distribution,and root dry weight percentage distribution.Soil penetration resistance was one of important factors restricting soybean root development for the significant negative relationship between soil penetration resistance and root length density,root surface area density,root volume density,and root dry weight density,respectively.