Supporting farmers in selecting the most suitable nitrogen source is essential for balancing crop productivity with environmental sustainability. Trials comparing different fertiliser types showed that granulated cattle manure and green waste compost led to smaller maize yield increases and should be used alongside mineral fertilisers rather than alone. In these specific trials, combining a reduced rate of ammonium nitrate (80 kg N/ha) with organic fertilisers-maintained yields comparable to full mineral fertilisation (170 kg N/ha). This suggests that, when growing maize for grain, farmers can rely on granulated poultry manure as a primary nitrogen source before sowing, while other organic fertilisers may be better suited as complements to mineral inputs. However, full-rate ammonium nitrate and poultry manure fertilisation (170 kg N/ha) left elevated levels of mineral nitrogen in the soil post-harvest, raising concerns about nitrate leaching.