Abstract:
Phosphorus (P) is an essential macronutrient for plant growth and is mainly present in agricultural soil in unavailable forms. Phosphate-solubilizing microorganisms (PSMs) increase soil P availability. The objective of the present study was toassess the population and type of PSMs and their relationships with soil characteristics in the agricultural soil of Manokwari.
wenty-one composite soil samples (0–20 cm) were collected at the rhizospheres of plants in the Prafi and Masni Districts.A dilution technique and plate count method on Pikovskayas agar medium were used to examine the PSM population,
phosphate-solubilizing index (PSI), and various soil properties. The results obtained showed that the total population ofphosphate-solubilizing bacteria ranged between 25×103 and 550×103 CFU g–1 of soil, while that of phosphate-solubilizingfungi was between 2.0×103 and 5.0×103 CFU g–1 of soil at all locations. The PSI of the isolates ranged between 1.1 to
3.6 mm, with the most efficient and highest PSI being obtained for Bacillus sp. (strain 8) and the lowest for Pseudomonas sp. (strain 15). Six isolates found at all locations were identified at the genus level: Chromobacterium sp., Pseudomonas sp.,Bacillus sp., Micrococcus sp., Caulobacter sp., and Aspergillus sp. A correlation was observed between the number of PSMsand the level of soil P availability and moisture content, indicating an increase in soil P availability with a greater abundanceof PSMs in soil.