Dr Daniel Hendrie1, Prof. Roger Armstrong1
1DEECA – Agriculture Victoria Research
Biography:
Daniel is a researcher in the Soil Sciences team at AVR in Horsham. His research focuses on spatially explicit amelioration of subsoil constraints to improve crop production and reduce yield gaps in Western Victorian cropping systems. He is also involved in developing screening procedures and identifying lentil germplasm with greater tolerance to soil acidity.
Abstract:
Subsoil physiochemical constraints commonly occur across Australia’s dryland cropping regions where they limit the ability of roots to extract water and nutrients from the subsoil. In a simple experiment we were able to demonstrate the relationship between crop rooting depth, grain production and seasonal rainfall on four soil types containing various physicochemical constraints across two paddocks in Western Victoria. By supplementing rainfall with either 80 mm of irrigation over winter or 160 mm spread over winter and spring in 2021, canola rooting depth was significantly reduced (P=0.037), but grain yield was increased (P<0.001) compared to the non-irrigated dryland crop (327 mm growing season rainfall) on both a Sodosol and a Vertosol within a paddock at Nurrabiel. Similarly at Wallup, irrigation reduced the rooting depth of wheat in a highly alkaline Calcarosol (P=0.032, 251 mm growing season rainfall) but it had no effect in a Vertosol, in which rooting depth was less overall (P=0.081). Wheat yield was unaffected by irrigation (P=0.258) on either soil type at this site, which was attributed to a potential nitrogen limitation. This data suggests that in wetter seasons, where topsoil water content is regularly replenished by rainfall, crop root growth is less likely to be impacted by subsoil constraints. Conversely, to access deeper subsoil water, crops invested more resources into growing roots deeper into constrained subsoils, which impacted on grain yield. These findings have implications for and soil management in future climates.