Boosting Water Savings with Mulch: A New Approach
A groundbreaking innovation from CSIRO aims to revolutionize soil moisture conservation techniques. By utilizing crop residues, they've developed a composite mulch batt that not only enhances soil health but also significantly reduces water evaporation. This approach addresses the limitations of traditional plastic mulching, which is not sustainable for broadacre cropping.
The project, funded by the GRDC, involves creating a sprayable mulch film tailored for low to medium-rainfall areas. Dr. Stuart Gordon, a Senior Principal Research Scientist at CSIRO Agriculture and Food, leads this initiative. The goal is to achieve a biodegradable water vapor transfer barrier that outperforms plastic sheeting in moisture preservation.
Dr. Gordon explains that while plastic sheeting is highly effective in lab conditions, its performance degrades in the field due to damage and environmental factors. In contrast, straw application can mimic plastic's moisture-saving capabilities over a growing season. The research team's target is to reach this level of effectiveness.
The key innovation lies in a sprayable, biodegradable mulch formula based on polyurethane particles coated with cellulose. This powder-like substance acts as a binder for chopped stubble or chaff, creating a composite batt on the soil surface. The batt's microclimate and moisture-retaining properties are crucial for crop germination.
The mulch powder's application is versatile. It can be applied dry or after moisture events, mixed with water for spraying, or 'melted' using low-temperature heat rollers. The polyurethane backbone, enriched with amine and urea groups, provides flexibility and bonding strength, ensuring the batt's stability and longevity.
Field trials in 2026 will assess the mulch's performance, including its ability to moderate soil drying and crusting, and its compatibility with sowing equipment. Early laboratory and small plot trials have demonstrated the formula's effectiveness, with over 50% biodegradation within 8 months.
The research also explores the potential for weed suppression by adding pigments to block sunlight. Furthermore, the formula can be enhanced with actives to protect against soil pathogens and nematodes, leveraging polyurethane's slow-release properties. The team is also investigating the use of refined cereal residues and even recycled cotton clothing as binders.
CSIRO is committed to domestic production, aiming to assess the feasibility of manufacturing the specific polyurethane formula locally. Production costs and application rates are crucial factors in ensuring the mulch's affordability and effectiveness. A prototype product is set to be released in 2026 for further testing and refinement.
This innovative approach to mulch technology holds promise for sustainable agriculture, offering a more environmentally friendly and effective solution for water conservation in cropping systems.
