Nutrient recycling through the conversion of waste sheep wool and poultry litter incineration ash into fertilizer: its effect on wheat and subsequently grown maize

A biocomposite basal fertilizer was developed from waste sheep wool and poultry litter incineration ash. The fertilizer, designated as WAsh (4.50:8.35:8.75), was characterized using SEM, XRD, PEDXRF, and FTIR techniques. Wheat was first grown with WAsh applied at 100 and 200 mg kg^− 1 P as a basal fertilizer, followed by maize cultivation in the same soil to assess residual effects. The WAsh significantly increased dry matter accumulation and nitrogen and phosphorus concentrations in both wheat and the subsequently grown maize. In wheat, shoot dry weight increased from 81.7 to 89.9 g per pot, N concentration from 6.79 to 11.6 g kg^− 1, and P concentration from 0.24 to 0.84 g kg^− 1. In the grains, P concentration rose from 2.71 to 4.09 g kg^− 1. In the second crop maize, dry weight increased from 15.4 to 45.3 g per pot and P concentration from 1.20 to 2.17 g kg^− 1, indicating that the residual effect of WAsh persisted strongly. Post-harvest soil analyses showed that WAsh increased plant-available P after both crops, slightly reduced soil pH, and elevated EC at higher doses. In conclusion, WAsh proved to be a slow-release, nutrient-rich organomineral fertilizer that enhances crop productivity and nutrient recycling while maintaining soil quality.