In‐field evaporative protection for dryland wheat and lentil crops using polymers

Abstract

AbstractIn semi‐arid cropping regions where rainfall is variable, stored soil water is important for reducing the impacts of dry periods; however, in‐season evaporation limits yield potential. We tested the productivity benefits of protecting wheat and lentil crops from evaporation using inter‐row polymer cover, when grown in southern Australia. For wheat, white polyvinyl chloride (PVCw) increased yield by 50% (561 kg/ha) and 11% (408 kg/ha) for decile 2 (2018) and 3 (2019) seasonal rainfall respectively; and for lentil, yield increases were 20% (443 kg/ha) in 2019. A sprayable alginate polymer increased wheat yield by 8% (310 kg/ha). Total water use for wheat in 2018 was reduced (17 mm) for PVCw and water use efficiency (WUE) significantly increased from 7 to 11 kg/ha/mm, whereas in 2019, WU was greater (47 mm) for PVCw, but WUE was equivalent to the control (~15 kg/ha/mm). Colour of the PVC modified the light available to the crop and canopy temperature, where a highly reflective inter‐row cover (albedo 0.44) increased wheat yield (~487 kg/ha). For the future, formulations of highly reflective polymers applied in‐season within dryland cropping enterprises are likely to provide production advantages, although logistical viability of application and potential environmental implications may define impediments to adoption.