Soybean fallow and nitrification inhibitors: Strategies to reduce N2O emission intensities and N losses in Australian sugarcane cropping systems

The Australian sugar industry is facing mounting pressure to reduce the nitrogen (N) losses and nitrous oxide (N2O) emissions associated with N fertiliser use. Research has shown that N2O from sugarcane (Saccharum officinarum L.) cropping systems can be reduced use of fertilisers coated nitrification inhibitors, or by sowing legume crops in fallows between crop cycles. However, efficacy these two management strategies across different climatic zones still unclear, as results field studies have been contradictory. objectives this study were therefore DayCent model assess long-term effects (separately combination) on emissions, yields. was parameterised using data eight experiments (39 treatments) conducted four five main districts industry. A series scenarios embracing a range rates (0?160 kg ha?1 applied urea), regions (Tropics Subtropics), soil textures (fine- coarse-textured soils) N-loss risk (crop fertilised well before close on-set wet season) tested for both strategies. Simulations identified combined soybean (Glycine max 3,4-dimethylpyrazole phosphate (DMPP) inhibitor most effective strategy maintain even increase current yields while significantly reducing cumulative (mainly due nitrate) losses. When used alone, fallow average over entire cycle 29 % compared best practice. showed limited capacity cane (median: -3% practice), increased them at high-risk Tropics. urea DMPP alone allowed 30 without any substantial yield penalty. In environments prone high losses, abated overall 41 %, respectively. This first such an extensive dataset parameterise biogeochemical yields, systems. findings will instrumental guiding future research policies designed improve profitability environmental sustainability