In a world grappling with rising costs of mineral fertilisers and the pressing need for sustainable manure management, a recent study offers a promising alternative that could reshape agricultural practices and benefit the energy sector. Published in the *Journal of Sustainable Agriculture and Environment* (translated as ‘Journal of Sustainable Agriculture and Environment’), the research led by Joana Prado from the Instituto Superior de Agronomia at the University of Lisbon, explores the potential of manure-based fertilisers (MBFs) to enhance nitrogen mineralisation and reduce greenhouse gas emissions.
The study, conducted by Prado and her team at LEAF, TERRA, investigated the use of MBFs with tailored nitrogen to phosphorus (N:P2O5) ratios—1:1, 2:1, and 0.5:1—to evaluate their impact on nitrogen mineralisation, nitrification rates, and greenhouse gas emissions when applied to sandy soil. The researchers used raw manures from cattle, pigs, and poultry, manipulating them to achieve the desired ratios.
The findings revealed that cattle and pig slurries, when applied in a 1:1 N:P2O5 ratio, exhibited higher mineralisation rates—around 35% of the organic nitrogen applied—and lower environmental impact compared to poultry manure. “This indicates that these slurries are more efficient in releasing nitrogen in forms that plants can uptake, while minimising environmental harm,” Prado explained.
For the 2:1 ratio, blending poultry manure with urea significantly improved nitrogen mineralisation rates and halved the emissions of nitrous oxide (N2O) and carbon dioxide (CO2) compared to raw poultry manure. “This enhancement not only boosts the fertiliser value of poultry manure but also mitigates its environmental footprint,” Prado added.
The study also found that adding superphosphate to poultry manure decreased N2O emissions and maintained a similar nitrification rate as the raw material. This suggests that tailored MBFs can offer both agronomic and environmental benefits.
The implications of this research are far-reaching. For farmers, the use of MBFs could reduce dependency on costly mineral fertilisers while improving soil health and crop yields. For the energy sector, the reduction in greenhouse gas emissions aligns with global efforts to combat climate change, potentially opening avenues for carbon credits and sustainable energy practices.
As Prado noted, “This research demonstrates that it is possible to produce MBFs with specific N:P2O5 ratios that are not only effective but also environmentally friendly. It’s a win-win for agriculture and the planet.”
The study, published in the *Journal of Sustainable Agriculture and Environment*, underscores the importance of innovative solutions in sustainable agriculture. By harnessing the power of manure-based fertilisers, farmers and energy sector stakeholders can pave the way for a more sustainable and profitable future.