Bioactivation of Legacy Phosphorus in Calcareous Soil and its Impact on Maize Yield

Background: Over the years, the excessive P fertilizer application to crop fields resulted in the build up of insoluble phosphorus pool in soil known as legacy phosphorus. This represents a vast and largely untapped resource in soil. The current study was conducted to evaluate the potential of some P activators (Phosphorus solubilising bacteria, phytase, humic acid, farmyard manure) on increasing the plant availability of legacy P in calcareous soil. Methods: A field experiment was conducted with maize hybrid COH(M) 6. The P activators were combined and applied along with the different doses of P fertilizer (100%, 75% and 50% soil test dose of single super phosphate). Result: Farmyard Manure (FYM) application with Humic acid (HA) showed the increased Olsen P under 100% and 75% of P application. The phosphorus activation response of FYM+HA applied plots showed a higher value than other treatments. The maize yield and P uptake obtained with FYM and HA were statistically comparable at 100% and 75% soil test dose of P. The findings have illustrated that even the reduced amount of P fertilizer application can support the crop growth due to the release of legacy P if they are applied along with P- activators such as FYM and HA.