ORGANIC ACIDS AND COMPOSTING: INNOVATIVE METHODOLOGIES FOR OBTAINING AVAILABLE PHOSPHORUS

Abstract

The cost of importing phosphorus (P) as a macronutrient for crops has increased significantly in recent years, although there are deposits of phosphate rock (PR) in Colombia these have P contents of low bioavailability. This work evaluated the effect of low molecular weight organic acids (LMWOAs) in the extraction of P from PR under controlled laboratory conditions. I was also tested their incorporation with PR in biotransformation processes to obtain P-assimilable (PA). Laboratory tests were performed with formic, acetic, acetic, propionic, butyric, citric, maleic, malonic, succinic, glutaric, adipic, phthalic, malic, tartaric, and oxalic acids in reaction tubes, under controlled temperature conditions at 25°C and 60°C, at 0 and 10 days. The concentrations of solubilized P found with citric, maleic, malonic, tartaric, malic, and oxalic acids corresponded to solubilization values greater than 5.0%, these being the LMWOAs with the highest potential for P extraction from PR. The biotransformation processes were set up with chicken manure, sawdust, PR, and oxalic acid at field level, as well as with municipal solid waste organic fraction (MSWOF), PR and oxalic acid in 60 cm3 reactors; these processes were carried out with the purpose of obtaining P-rich organic-mineral nutritional mixtures. The MSWOF generated a biomass with a higher concentration of PA than chicken manure; the result is conclusive of the greater fertilization potential of the MSWOF substrate with respect to the mixtures with chicken manure, given the greater availability of P found.