Does cassava wastewater with a short incubation time affect soil organic carbon, microbial community and enzymatic activities?

The reuse of agro-industrial residues that have no toxic impact on the soil is an alternative means of plant nutrient supply that is important to farmers and the environment cassava wastewater (CW) is considered as an alternative fertilizer because it is rich in nutrients that are essential for plants, particularly potassium, magnesium, phosphorus, and calcium. The objective of this study was to investigate the impact of different CW concentrations (25%, 50%, and 75%) on the quality of sandy Entisol over 28 days. CW application was beneficial to the soil microbial population as indicated by the higher microbial biomass carbon values of this sandy Entisol compared with the values in the control. The soil bacteria population was not affected by CW use. However, a decrease in the total fungi (TF) population was observed in all treatments at 7 and 14 days after application (DAA) of CW followed by a significant increase at 21 and 28 DAA. CW applied to the soil in concentrations of 25% and 50% reduced its arylsulfatase activity. Principal component analysis showed an initial impact of CW application to sandy Entisol, revealing that the highest total bacteria, TF, acid phosphatase activity, and soil basal respiration values were recorded in the control treatment during the first evaluation at 7 DAA. At 21 DAA of CW, TF and soil basal respiration vectors are toward the treatments that received the highest CW concentrations. Therefore, this study showed clear evidence that the populations and activities of microorganisms, mainly the fungi population, have a high resilience capacity and ability to power of adaptation when CW is employed. To the best of our knowledge, we provide some of the first data related to the beneficial effects of reusing of an agro-industrial waste material (CW) on the quality of tropical sandy Entisol.