Forage yield of buffel grass (Pennisetum ciliare) using PHYGROW model in thinned Caatinga

Animal production in semi-arid regions relies heavily on natural and cultivated pastures, which are vulnerable due to the variability of rainfall. This study evaluated the PHYGROW model's ability to predict the forage yield of buffel grass (Pennisetum ciliare) in thinned Caatinga and assess production risk. The research was conducted in Santa Terezinha, Paraíba, Brazil, in an experimental area under a silvopastoral system (15-20% woody cover) enriched with buffel grass. Field data from studies conducted between 2008 and 2014 were used, and biomass yield was estimated using PHYGROW software. The model's results were analyzed statistically, and risk analysis was conducted using the concept of the natural guarantee of local production. The PHYGROW model showed high accuracy in predicting forage yield, estimating an annual dry matter yield of 1,862.7 kg/ha with 95% confidence. The findings suggest that this modeling approach is a valuable tool for improving farm planning in semi-arid regions, helping reduce reliance on empirical methods by linking yield predictions to a quantified risk factor.