Organic Wastes Amended with Sorbents Reduce N2O Emissions from Sugarcane Cropping

Nutrient-rich organic wastes and soil ameliorants can benefit crop performance and soil health but can also prevent crop nutrient sufficiency or increase greenhouse gas emissions. We hypothesised that nitrogen (N)-rich agricultural waste (poultry litter) amended with sorbents (bentonite clay or biochar) or compost (high C/N ratio) attenuates the concentration of inorganic nitrogen (N) in soil and reduces emissions of nitrous oxide (N2O). We tested this hypothesis with a field experiment conducted on a commercial sugarcane farm, using in vitro incubations. Treatments received 160 kg N ha−1, either from mineral fertiliser or poultry litter, with additional N (2–60 kg N ha−1) supplied by the sorbents and compost. Crop yield was similar in all N treatments, indicating N sufficiency, with the poultry litter + biochar treatment statistically matching the yield of the no-N control. Confirming our hypothesis, mineral N fertiliser resulted in the highest concentrations of soil inorganic N, followed by poultry litter and the amended poultry formulations. Reflecting the soil inorganic N concentrations, the average N2O emission factors ranked as per the following: mineral fertiliser 8.02% > poultry litter 6.77% > poultry litter + compost 6.75% > poultry litter + bentonite 5.5% > poultry litter + biochar 3.4%. All emission factors exceeded the IPCC Tier 1 default for managed soils (1%) and the Australian Government default for sugarcane soil (1.25%). Our findings reinforce concerns that current default emissions factors underestimate N2O emissions. The laboratory incubations broadly matched the field N2O emissions, indicating that in vitro testing is a cost-effective first step to guide the blending of organic wastes in a way that ensures N sufficiency for crops but minimises N losses. We conclude that suitable sorbent-waste formulations that attenuate N release will advance N efficiency and the circular nutrient economy

On farm evaluation of vegetable seed viability using non-destructive techniques

Vegetable crops that are field-established from seed, like corn, beans, carrots and spinach, need high-quality seed to avoid substandard crops. To help growers and encourage collaboration between industry, scientists and seed producers, this levy-funded project identified on-farm issues relating to seed quality, with an end goal of optimising seed longevity and maximising the success of seedling establishment. The project also reviewed emerging non-destructive and cost-effective technologies that can screen viable seed, with a view towards maximising germination and vigour of seedlings once planted. Recommendations were developed for R&D programs that could help solve the seed quality challenges facing the Australian industry

Closing the green city loop project

Systematically manufactured biochars were prepared by three distinct commercial pyrolysis technologies and compared against conventional composting technologies. New products were tested across urban horticultural commodities, including nursery, turf and fruit industries. Economically viable markets for these carbon-rich matrices made from recycled organics were identified within key horticultural sectors