Evaluation of the impact of age on compost quality at Mbarara Municipal compost plant in south western Uganda
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The composting industry, including producers, testing laboratories, marketers and consumers have a well-documented need to know the specific chemical, physical and biological properties of compost products. Composting has become a preferred method for municipalities and industries to recycle a variety of organic byproducts often regarded to as “wastes” thus transforming them into useful soil conditioners and amendments. The safety and quality assurance of compost product as a soil vitalizer and amendment are required to meet the needs of agricultural, horticultural, silvicultural and landscape markets both nationally and internationally. However, currently there exists no industry or laboratory wide sampling and testing the quality and protocols of compost product. The objective of this research was to assess the quality of compost produced at Mbarara Municipal Compost Plant in reference to the international standards for high quality compost. The study followed a whole composting process of Mbarara Municipal Compost Plant which has been producing compost in western Uganda for the past nine years. The impact of age on compost quality in terms of nutrient content at different stages of composting was tested. Most compost parameters tested such as C: N ratio (18:1-23:1), pH (9.8), %OC (15.54±3.47) % and %N (0.79±0.04) % were found within acceptable limits set by international standards of high quality compost as of July 2017. % P (0.46±0.01) % and % K (2.14±0.08) % tested in final sieved compost product were within critical levels for agronomic soil conditioning although international standards for them are not stated. However, the texture tested in Mbarara municipal compost at all stages of composting was found to be apart from the expected texture of high quality compost with sandy loam as the textural class for all samples. This therefore calls for investigation about the possible sources of the high sand content in the compost and at what stage it gets there. Generally, compost produced at Mbarara Municipal Compost Plant can be used as a good soil vitalizer and the same composting technology would be a great deal if adapted in all municipalities of Uganda to utilize an often neglected resource “municipal solid waste” into a useful resource to vitalize the depleted soils of Uganda. However, to further improve quality of compost and its sustainable production, a well-equipped laboratory to test compost quality and ensure quality assurance for compost produced at the plant for different markets should be established at the plant.