Wheat root penetration and total available water on a range of soil types

Abstract

Depth of root penetration was examined over three years on a range of soil types in Western Australia. A consistent pattern was recognized. Roots penetrated rapidly to 5 to 10 cm from the soil surface within the first week from planting. Subsequent penetration was slow to 6 weeks, at which stage, depending on soil types, depth of root penetration was 15 to 30 cm. Rates of root penetration increased after 6 weeks from planting with greatest penetration occurring between 8 to 13 weeks. Respective maximum depths of root penetration in the deep sand, sandy loam, grey clay and sand over clay soils investigated were 169, 173, 31 and 73 cm. These depths were reached between 10 to 14 weeks after planting. Potential available soil water to maximum depths of root penetration were 2.6, 20.1, 5.6 and 8.1 cm for the deep sand, sandy loam, grey clay and sand over clay respectively. More than half of this available soil water was accessible for crop exploitation over the 9 to 14 week period after planting, except with shallow water and root penetration in the grey clay.