Penetration of pea radicles into saturated soil cores related to organic matter amendments

Abstract

The radicles of pea seedlings penetrated to different depths in saturated cores prepared from Goulburn Valley orchard soil according to the amount and type of organic matter added to the soil. Additions of ground straw and glucose restricted the penetration of the roots when grown for 4 days at constant temperature. Longer incubation times and higher incubation temperatures imposed on the cores before growing the seedlings further restricted the roots in the presence of added peat, straw or glucose. The restrictions to root penetration can be attributed to poor oxygen supply into the saturated soil matrix and to phytotoxins produced by the microbial decomposition of organic matter contained in the soil cores. The results suggest that structural units in an irrigated soil should not be larger than about 6 mm in diameter if roots are to fully exploit the soil volume.