The present study aimed to determine the agronomic value of composts based on the effluent from the biodigester, which is a semi-buried structure with a fixed dome. The chemical characteristics of the composts and the soil were determined. The effects of the composts on the yield parameters of maize were evaluated using an experimental design. The design was in completely randomized blocks repeated six times. Each block included six elementary plots, each corresponding to a treatment: a control without fertilization, a treatment exclusively mineral, two plots amended only with compost, and two treatments combining compost and mineral fertilizers. The results showed that effluent-based composts have acceptable contents of organic matter (20.11 and 20.95%), nitrogen (0.66 and 0.75%), total potassium (0.51 and 0.62 g/kg), and carbon to nitrogen ratios (16 and 19) compared to the FAO’s evaluation grid for the quality of organic substrates. On corn, fertilization with this compost alone or in combination with mineral fertilizers had positive effects on biomass and grain yield compared to the control. The obtained results revealed the fertilizing value of effluent-based compost. Its use could be an alternative to improve agricultural yields.