Objective: This experiment was conducted to evaluate the forage quality and yield of three forage plants: Pennisetum glaucum (Nutrifeed variety), maize (Single Cross 260), and sorghum (Speedfeed variety) under the influence of combined levels of poultry manure and chemical fertilizers with the aim of reducing the use of chemical fertilizers and improving the quantity and quality of forage.

Materials and Methods: This study was conducted over two growing seasons (2023–24 and 2024–25) using a split-plot design based on a randomized complete block design with three replications at the Research Farm of University of Kurdistan, Dehgolan. The main factor was the forage species (Pennisetum glaucum, sorghum and maize) and the sub-plot factor consisted of fertilization systems: control; 4 t.ha-1 poultry manure; 3 t.ha-1 poultry manure + 50 kg.ha-1 Nitrogen from urea + 25 kg.ha-1 phosphorus from triple superphosphate; 2 t.ha-1 poultry manure + 100 kg.ha-1 Nitrogen from urea +50 kg.ha-1 phosphorus from triple superphosphate; and full chemical fertilization (200 kg.ha-1 Nitrogen from urea + 100 kg.ha-1 phosphorus from triple superphosphate). Qualitative traits (water-soluble carbohydrates, crude fiber, crude protein, neutral detergent insoluble fiber, acid detergent insoluble fiber, and ash) and quantitative trait (biological yield) of forage were measured, and the data were analyzed with SAS version 9.4 software.

Results: The results showed that the highest water-soluble carbohydrate of forage in the treatment of complete chemical fertilizer and 100 kg/ha nitrogen fertilizer from urea source + 50 kg phosphate from triple superphosphate source was corn plant. The lowest crude fiber of forage was in the treatment of 2 tons/ha chicken manure + 100 kg/ha nitrogen fertilizer from urea source + 50 kg phosphate from triple superphosphate source of pearl millet, the highest crude protein of forage was in the treatment of 2 tons/ha chicken manure + 100 kg/ha nitrogen fertilizer from urea source + 50 kg phosphate from triple superphosphate source in corn plant, which had no statistically significant difference with the percentage of crude protein of forage in the treatment of 3 tons/ha chicken manure + 50 kg/ha nitrogen fertilizer from urea source + 25 kg phosphate from triple superphosphate source (14.06%). The highest amount of neutral detergent insoluble fibers was obtained in the treatment of applying 4 tons per hectare of poultry manure to pearl millet plants. The highest forage ash was related to the treatment of applying pure chemical fertilizer. Also, the application of 2 tons per hectare of poultry manure + 100 kg per hectare of nitrogen fertilizer from the urea source + 50 kg of phosphate from the triple superphosphate source resulted in the highest biological yield.

Conclusion: Combined fertilizer treatments (2 t.ha-1 of poultry manure + 100 kg.ha-1 of nitrogen fertilizer from urea source + 50 kg of phosphate from triple superphosphate source) resulted in significant improvement in forage quality and yield in corn as well as improvement in some quality indicators in Pennisetum glaucum and sorghum. Using poultry manure in combination with chemical fertilizer can reduce costs and environmental impacts, while maintaining or increasing crop productivity.