Journal of Agricultural Science and Food Research

Journal of Agricultural Science and Food Research
Open Access

ISSN: 2593-9173

+44 1223 790975


Effect of Nitrogen Form on the Effectiveness of a Phosphate-Solubilizing Fungus to Dissolve Rock Phosphate

Mitiku Habte and Nelson Walter Osorio

An in vitro experiment was carried out to evaluate the effect of nitrogen (N) form (NH4+ and/or NO3-) on the dissolution of rock phosphate (RP) by a phosphate solubilizing fungus (PSF) identified as Mortierella sp. In the presence of NH4Cl or NH4NO3, the solution of pH significantly decreased from an initial value of 7.6 to 3.4 and 3.7 respectively. In the presence of KNO3, the pH went down only to 6.7. As a result, significantly more P was detected in solution in the presence of NH4Cl (129.65 mg/L) than in the presence of NH4NO3 (109.25 mg/L). The concentration of P in solution in the presence of KNO3 was only 0.08 mg/L. The excess of NH4+ adversely affected the growth of Mortierella sp. However, this may have promoted a more active H+-pumping that decreased solution’s pH. In the presence of NO3- as the only source of N, Mortierella sp. not only dissolved a small amount of Pi from the RP but also immobilized most of it into its mycelia. In contrast, in the presence of NH4Cl, Mortierella sp. was effective to dissolve RP and the Pi released remaining in solution while only a little portion was immobilized by the fungal mycelia.