Microalgae biomass as a renewable biostimulant: meat processing industry effluent treatment, soil health improvement, and plant growth.

Microalgae biomass contributes to effluent bioremediation. It is a concentrated source of nutrients and organic carbon, making it a potential alternative as a soil biostimulant. In this context, this study aimed to evaluate the soil application of microalgae biomass produced from the meat processing industry effluent treatment. The biomass was applied dry and as a mixture to demonstrate its potential to increase plant production and soil metabolic functions, analyzed short-term. Doses of 0.25%, 0.5%, 1%, and 2% biomass were applied in soils from (i) Horizon A: taken at a depth between 0 and 10 cm and; (ii) Horizon B: taken at a depth between 20 and 40 cm. Corn growth (Zea Mays L.), basal soil respiration, microbial biomass carbon, total organic carbon, ß-glucosidase, acid phosphatase, arylsulfatase, and urease enzymatic activity were evaluated in each sample. It is concluded that applying 2% microalgae biomass led to higher basal soil respiration, microbial biomass carbon, and ß-glucosidase, acid phosphatase, arylsulfatase enzymatic activity in both soils. On the other hand, boron may have contributed to urease activity reduction in Soil A. Although 2% biomass led to higher soils characteristics, that dose did not promote higher plant growth. Hence, considering that plant growth must be in line with changes in soil characteristics, the result that provided the higher plant shoot dry matter mass was by applying 0.55% biomass in both soils. Therefore, the application of microalgae biomass produced from a meat processing industry effluent treatment promoted a biologically active soil and boosted plant growth.