Abstract
This glasshouse pot experiment demonstrated that a new sprayable and degradable polymer reduced soil water evaporation and promoted cotton seedling emergence and establishment. The polymer was tested on two contrasting soils (sandy loam and clay), representative of those used to grow cotton in Australia. Changes in soil water content in non-treated and polymer-treated pots were monitored over 80 days, after surface or subsurface watering. Plant biomass, soil water content and soil chemical properties were determined at harvest. The polymer reduced soil water evaporation by up to 35% in sandy loam and up to 20% in clay, did not compromise seedling emergence and improved plant growth per unit water applied by up to 26.2%. The polymer underwent extensive degradation after 80 days to produce low molecular-weight polymers or oligomers and water-extractable silicon species that may have implications for plant nutrition.
Highlights
As access to water will become more variable in Australia’s cotton growing regions due to climate change (Roth et al 2013), the economic viability of Australia’s cotton industry will increasingly rely on efficient use of scarce water resources
Numerous water management strategies have already been successfully implemented by Australian cotton growers to improve crop water use efficiency (WUE), but further significant improvements can be made through the adoption of emerging materials-based water-saving technologies (Adhikari et al 2016, 2019)
The barrier efficacy of the polymer was better maintained throughout the length of the trial in the SS pots, whereas protection against soil water evaporation in S pots decreased over time
Summary
As access to water will become more variable in Australia’s cotton growing regions due to climate change (Roth et al 2013), the economic viability of Australia’s cotton industry will increasingly rely on efficient use of scarce water resources. Mulching with polyethylene or oxodegradable plastic films in furrow irrigated and rainfed cotton and other crops reduces soil water evaporation and increases cotton emergence and establishment through a combination of soil water conservation, increased soil temperatures and weed suppression (Anzalone et al 2010; Braunack et al 2015; Yan and Li 2016). Specialised equipment is required to apply preformed non-biodegradable plastic mulches, so a sprayable, degradable polymer could eliminate the expense of specialised laying equipment. There is increasing interest in the development of sprayable materials that reduce soil water evaporation and that can be applied using existing farm spray equipment. Notable spray-on materials have been derived from polysaccharides (Immirzi et al 2009), waste leather products (Sartore et al 2018), polysiloxanes (Al-Kalbani et al 2003), biodegradable
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