Evaluation of Pomegranate Fruit Powder Coated on Urea as Urea-N Immobilizer and Soil-P Mobilizer

It has been shown that pomegranate fruit powder (PFP) has the potential to decrease urea-nitrogen (N) mineralization and improve grain yield of maize, but the mechanisms of this effect are not fully understood. Therefore, the objective of this study was to investigate these mechanisms. For this purpose, an incubation and a pot experiment were conducted, in which four levels of PFP coating equivalent to 0%, 30%, 70%, and 100% (w/w) of urea were studied. PFP had very little effect on nitrification (1.4-2.9%). Mineral N and nitrite (NO2-)-N decreased (23% and 38%, respectively) with increasing PFP application, probably due to N-immobilization or urea hydrolysis inhibition. Biomass and grain yield of maize increased with increasing phosphorus (P)/N ratio of leaf and stem, and decreasing P/N ratio of grain, indicating soil-P-mobilization and soil-N-immobilization during vegetative growth and the inverse, during grain filling by PFP. According to these results, PFP can be introduced as an urea-N immobilizer and soil-P mobilizer.