Ammonium sulphate from manure scrubbing for crop nutrition

Ammonium sulphate, a nitrogen and sulphur fertilizer produced from ammonia recovery in manure, shows comparable agronomic performance to conventional fertilizers in lettuce and maize trials. It contains NH₄-N and sulphur, with variable pH (2.40–6.43) and high electrical conductivity (157–262 mS cm⁻¹), posing risks for equipment corrosion. Field studies across seven trials indicate similar yields, nitrogen use efficiency (NRUE), and fertiliser replacement value (NFRV) to synthetic sources. Post-harvest nitrate residues remained below 90 kg NO₃⁻-N ha⁻¹ in most cases, though weather and soil conditions affect outcomes. Combined manure and ammonium sulphate applications improved nitrogen uptake in one maize study. Legal classification depends on nitrogen content, with EU regulations treating it as a mineral fertilizer if N >15%. The SYSTEMIC project, funded by Horizon 2020, confirms its potential for sustainable nutrient recovery and reduced leaching, though salt-sensitive crops require caution.