The wetted areas in the A horizon on the delving line, off-line, and in the undelved soil were greater than those shown in Fig.
At 0.3-0.6 m depth (B22 horizon), the disruption of the A-B boundary contributed to deeper water penetration, and the wetted area on the delving line was -15% greater (significant at Z5-0.05) than in the off-line region.
The influence of clay delving on soil profile wetting was less evident at site B than at site A at Coonalpyn.
In the B21 horizon on the delving line, water infiltrated deeper as shown by the significantly greater area of wet (stained) soil than in off-line and undelved soils, by -7% and 13%, respectively (Fig.
1b), decreasing from the soil surface downward, with an abrupt increase above the A-B horizon where free water ponded, whereas water did not pond at the horizon boundaries on the delving line.
2012) caused by incomplete pre-wetting, but it is more likely that variations are simply due to large differences in soil composition and delving practices at the different sites.
Nevertheless, the soil disturbance on the delving lines promoted greater wetting in the B horizon than on the off-line region and in the undelved soil.
At all three sites in South Australia, clay delving significantly increased the proportion of the A1 horizon that wetted up during infiltration into dry soil, and the penetration of water below the A-B horizon boundary.
Most of the increase in soil wetting from delving occurred in the area of maximum soil disturbance directly on the delving line, especially
This outcome suggests that more uniform wetting of the soil profile could be achieved by narrowing the spacing of delving tines or through cross-delving and thereby reducing the extent of the off-line region, where finger flow still occurs.
Under dry conditions, clay delving significantly reduced preferential water (finger) flow, especially where water repellence at the soil surface was severe.
Nevertheless, in the A horizon the delved profiles showed significantly larger wetted areas, particularly along the delving lines, which can be crucial for plant root growth in semi-arid and Mediterranean areas (Lampurlanes et al.
Moreover, larger areas of wet profile at depth were achieved on the delving lines at all three sites under both dry and wet conditions by disruption of the boundary between the A and B horizons.
Although clay delving reduced finger flow and increased the uniformity of topsoil wetting plus water penetration to depth relative to undelved soil, the composition and physical properties of the delved soil were highly heterogeneous.