Excessive boron (B) levels in soil can lead to toxicity in plants, impacting their growth and productivity. Effective strategies to reduce B uptake are important for improving crop performance in contaminated soils. This experiment aimed to investigate the effects of chicken manure incineration ash (CMA) and triple superphosphate (TSP) on B uptake in barley plants grown in B-contaminated soil. Before the experiment, the chemical composition and molecular structure of CMA were analyzed using XRF, XRD and SEM. The soil was contaminated with 15 mg kg-1 of B, and both TSP and CMA were applied at rates of 40, 80, and 160 mg kg-1 of phosphorus (P). Neither P source had a significant impact on plant dry weight. However, increasing doses of applied TSP and CMA increased plant P concentration while significantly decreasing B concentration. Particularly with CMA applied at 160 mg kg-1 P dose, plant B concentration decreased to the lowest level of 194 mg kg-1. Increasing P doses led to a slight decrease in plant silicon (Si) concentration. The pH of soil samples taken after the experiment slightly increased with CMA treatments compared to TSP. The available P concentration in soils increased with increasing P doses. The available B concentration decreased with increasing P doses, especially reducing to the lowest level of 2.52 mg kg-1 in soils with a 40 mg kg-1 P, CMA. In conclusion, in addition to the effect of P, the molecular structure of P is also important in reducing B uptake in barley.