Farm Table says:
What is the problem?
Australian cotton is predominantly grown in heavy clay soils (Vertosols). Cotton grown on Vertosols often experience episodes of low oxygen concentration in the root-zone, particularly after irrigation events. In subsurface drip irrigation (SDI), cotton receives frequent irrigation and sustained wetting fronts are developed in the rhizosphere. This can lead to poor soil diffusion of oxygen, causing temporal and spatial hypoxia. As cotton is sensitive to waterlogging, exposure to this condition can result in a significant yield penalty.
What did the research involve?
This experiment was conducted using an existing SDI system on a cotton farm in Queensland, Australia on a Vertosol. The experiment was laid out in a randomized complete block design with 12 plots assigned to six replications of two irrigation treatments. Oxygenated water was thus delivered to the soil through the SDI tape.
What were the key findings?
The efficacy of oxygenation, delivered via SDI to broadacre cotton, was evaluated over seven seasons (2005–06 to 2012–13). Oxygenation of irrigation water by Mazzei air-injector produced significantly higher yields water-use efficiencies. Averaged over seven years, the yield and gross production water-use index of oxygenated cotton exceeded that of the control by 10% and 7%, respectively. The improvements in yields and water-use efficiency in response to oxygenation could be ascribed to greater root development and the increased light interception by the crop canopies, contributing to enhanced crop physiological performance by ameliorating exposure to hypoxia.
Oxygenation of SDI contributed to improvements in both yields and water-use efficiency, which may contribute to the greater economic feasibility of SDI for broadacre cotton production in Vertosols.