Quality Assessment by Aspergillus niger of an Onion, Cattle Manure and Alfalfa Waste Compost Blend

Using different agricultural waste composts as organic amendments or substrates for seedlings has increased in recent years. From remote times, organic waste has been associated with disease and agriculture fertility. However, determining the load of phytopathogenic microorganisms that can persist in mature compost is essential given the risk of them becoming a transmitter of disease. In the present work, A. niger survival in mature compost made with onion waste mixed with cattle manure and alfalfa waste was assessed. The relationships between the inoculum of A. niger loads present in mature compost and the quantitative ranges of the evaluated parameters were established. To this end, the Aspergillus nigerinoculum in the onion compost, obtained after a 6-month composting process, was used. The pH, EC and C:N ratio values in the three compost products do not limit them from being used as substrates in horticultural seedling production or as an organic soil amendment. These results are consistent with the research reported by other authors. Hence this compost can be successfully used as a substrate component in horticultural seedling production and as an organic fertilizer in soils without damaging crops.