Assessment of the suitability of biogas slurry for irrigation

In regions with irregular or insufficient water and rainfall, wastewater reuse has proven to be an alternative for irrigation, but there has been a growing concern for its effects on crop growth and yield as well as soil health and environmental sustainability. The research was conducted to evaluate the suitability of biogas slurry from anaerobic digestion of food waste and cow dung for irrigation. Biogas slurry samples were collected from single substrate digestion of food waste and co-digestion of food waste and cow dung. The physiochemical parameters were determined using standard methods while heavy metals were analyzed using an Atomic Absorption Spectrophotometer. The data obtained were subjected to statistical analysis using one-way analysis of variance (ANOVA), followed by Tukey’s HSD post-hoc test. The results showed that 69% of the physiochemical parameters and 66% of the heavy metals were within permissible levels of irrigation water. The addition of cow dung to food waste also showed there is a significant impact on more than 30% in the average value of the variables studied. The results obtained indicated that most nutrients were within irrigation standards and are essential anions needed for plant growth making it a valuable organic fertilizer for sustainable agriculture. From the study, it is concluded that the biogas slurries are about 67% suitable for irrigation. However, further studies with a larger sample size are needed to assess other parameters of the waste mixture such as total dissolved solid, total organic carbon, total organic matter, ammoniacal-hydrogen, Zinc, Copper and microbial load, to fully understand their potential as irrigation water as well as to assess the feasibility of using such mixtures to support large sized sustainable agriculture.