Evaluation of Several Biochar Types as Inoculant Carrier for Indigenous Phosphate Solubilizing Microoorganism from Acid Sulphate Soil

The research aimed at evaluating four biochar types which have the most adequate characteristics as inoculant carrier of indigenous Phosphate Solubilizing Microorganism (PSM) from acid sulphate soil. The observed biochar characteristics consist of the bulk density, total pore space, water holding capacity, C organic, N, pH, EC, charcoal percentage, and ash content. The pore diameters and photomicrograph of biochar were observed by using SEM. The viability test was conducted in order to determine the appropriateness of biochar as PSM inoculant through inoculation on four biochar types made of rice husk, coconut shell, corncob, and oil palm empty bunch, followed by six months storage period. Monthly observation was conducted related to the PSM population, pH, and moisture content. The results show that interaction of biochar types and storage periods has no significant effect on the PSM viability, pH, and moisture content. The PSM viability of four biochars after six months storage period is relatively stable in the range of log 7.07 cfu.g(-1) to log 9.18 cfu.g(-1). The highest PSM viability was found on coconut shell biochar with the magnitude of log 9.18 cfu.g(-1) and pH of 7.01 as well as moisture content of 26.86% after six months storage period. This research offers the advantage of using agricultural waste substance as biochar that capable to maintain microbial viability with six months storage period.