A comparative study of localized phosphorus application and broadcasting method on biomass production and their use...

Rhizospheric based phosphorus (P) fertilizer management is necessary for crop production due to environmental concerns caused by the overuse of the broadcasting method and limited P reserves. This study proposes a comparison of P management that enhances P nutrition in Chilli (variety: Arka Khyati) through seedling root-dipping (SRD) in P-enriched slurry (SSP-amended; pH of 8.1), micro-dose placement (MDP; drill and place closer to plant root), and full dose (187.6 mg kg^-1) placement by broadcasting (FD). In SRD, seedlings were dipped in five different P concentrations (50, 100, 200, 300, and 400 mg P₂O₅ kg^-1) for varying durations (0, ½, 1, 2, 3, and 4 hours) and transplanted into pots (dipping in 0 mg P₂O₅ kg^-1 consider as control), along with the MDP and FD treatments (total 33 treatments with 5 replications). [Seedlings dipped in 200, 300, and 400 mg P₂O₅ kg^-1 died within a week after transplanting, thus were excluded from further analysis]. The amount of P received in MDP and FD were 21-90 times higher than P adhesion to seedling roots in SRD treatments. Root volume was in order SRD>MDP>FD. Seedlings dipped in 100 mg P₂O₅ kg^-1 for 2 hours in SRD exhibited the highest biomass production, P-use and -recovery efficiency; and showed an increase of 52%, 178%, and 293% in FD, MDP, and SRD compared to the control respectively. It is recommended to use the SRD method with other P sources in reduced amount to maintain the native P pool in soil, and further multilocational trials are needed to validate.