Study of chemical properties and heavy metals in pig manure under different farm management systems in Ratchaburi province

Abstract

The aim of this research was to investigate chemical properties and some heavy metal concentrations in pig manure collected from swine farms that are managed under different systems. The swine farms selected for this study were in Ratchaburi province and consisted of farms under 3 different management systems, namely, conventional farming, GAP-based farming, and deep litter swine production with GAP standards. Swine production system data collection was conducted using an interview-based questionnaire. The collected pig manures were then analyzed for chemical properties and heavy metal contaminants in a laboratory. The results showed that the pig manure collected from farms with all of the farm management systems studied could be developed into organic fertilizer, since there was a high level of macronutrients (N-P₂O₅-K₂O), especially the pig manure from the farms under GAP-based farming systems, which contained 3.50% N and 3.50% P₂O₅, respectively. Although the pig manure collected from all production systems did not contain any of the heavy metal contaminants measured at rates exceeding the organic fertilizer limits, including those of As, Pb, Hg, and Cd, there was a high risk of copper contamination, which may be attributed to feeding, waste management, and farm floor management systems. In addition, some farms under GAP-based farming systems (40% of the interviewed farms) and GAP-certified deep litter swine production systems (20% of the interviewed farms) were found to generate stable income and gained some profits after deducting costs. In contrast, swine farms under a conventional system generated unstable earnings.