A new collaborative study from The University of Western Australia has found that partially replacing synthetic nitrogen fertiliser with low amounts of organic components can improve soil quality, crop productivity and nitrogen uptake.
Published in Land Degradation and Development, scientists investigated the effects of organic and synthetic fertiliser inputs on soil quality and crop performance.
The study, co-authored by Hackett Professor Kadambot Siddique from The UWA Institute of Agriculture and international research partners from China, examined a winter wheat–summer maize rotation under different nitrogen management strategies, including sufficient and reduced nitrogen application, combined with low and high rates of organic fertiliser.
Around 60 per cent of global urea-based nitrogen fertiliser supply passes through the Strait of Hormuz. With a significant share of global fertiliser supply on hold, Australia's imports have suffered from ongoing geopolitical disruptions which have intensified fertiliser shortages and cost pressures for Australian growers.
Professor Siddique said the study had special relevance due to the fertiliser supply and cost pressures around the world.
"Australian growers are seeking efficient use fertiliser to ensure economic growth and food security." he said.
"By analysing the combined effects of organic and inorganic inputs, this study provides insight into how fertiliser strategies can be adjusted to maximise agronomic, ecological and now economic outcomes."
The researchers suggest that optimising the balance between organic and synthetic nitrogen fertiliser inputs is critical for improving nitrogen use efficiency, enhancing soil quality, and reducing greenhouse gas emissions from agriculture.
These improvements supported higher crop productivity and greater nitrogen uptake, indicating more efficient nutrient cycling within the soil–plant system.
The findings contribute to a growing body of research focused on improving nutrient-use efficiency and soil management.
The study also found that treatments combining reduced nitrogen with organic fertiliser significantly reduced annual nitrous oxide emissions compared with full nitrogen application.
"Reducing synthetic nitrogen by less than 45 per cent while applying organic fertiliser can maintain productivity without increasing emissions," Professor Siddique said.
