ABSTRACT The use of poultry litter as organic fertiliser will enhance the agronomic performance of Panicum maximum cv. Mombasa grown in the Brazilian Cerrado region. The objective of this research work was to verify the effect of poultry litter as a source of phosphorus (P) for Mombasa guinea grass production, as well as its effect on the chemical composition of clayey soil. Throughout two years, six fertilisation strategies were tested: control, without organic or chemical fertilisation; 25% organic fertiliser and 75% inorganic fertiliser; 50% organic fertiliser and 50% inorganic fertiliser; 75% organic fertiliser and 25% inorganic fertiliser; 100% organic fertiliser; 100% inorganic fertiliser, represented by triple superphosphate (46% P2O5). Over the two years of evaluation, using 75 and 100% of poultry litter led to the highest values in forage mass accumulation rate and production (Year 1st: 106.91 kg ha−1 and 105.99 kg ha−1; Year 2nd: 98.29 kg ha−1 and 111.41 kg ha−1). These organic fertiliser proportions promoted increases in P concentration in the 0–0.05 m and 0.05–0.10 m layers. A partial (75%) or total (100%) use of poultry litter as organic fertiliser has a positive influence on forage production in the forage canopy of Mombasa guinea grass.