The use of organic matter is a highly accepted environmental practice among scientists for the bioremediation of polluted soils. In this manuscript we study under laboratory conditions the bioremediation capacity of a new biostimulant obtained from slaughterhouse sludge in a soil polluted by the oxyfluorfen at a rate of 4 l ha−1 (manufacturer’s rate recommended) over a 90-day period. We determined its effects on dehydrogenase, urease, β-glucosidase and phosphatase activities, the soil microbial community structure and the evolution of the herbicide in soil. Possibly due to the high content of low molecular weight proteins in the biostimulant, the enzymatic activities were stimulated mainly at the beginning of the experiment. Soil biological parameters were inhibited in oxyfluorfen-polluted soil. At the end of the experiment and compared with the control soil, dehydrogenase, urease, β-glucosidase, and phosphatase activities significantly decreased by 47.8%, 50.5%, 36.4%, and 45.5% in the oxyfluorfen-polluted soil. At 5 days into the experiment, the use of the biostimulant in oxyfluorfen-polluted soils decreased soil enzymatic activities and microbial community inhibition. At the end of the incubation period the oxyfluorfen concentration had decreased by 60% in the polluted soil and amended with biostimulants. These results suggested that the use of this biostimulant with higher amounts of low molecular weight proteins and peptides had a positive effect on the remediating oxyfluorfen-polluted soils. Therefore, this study provides the use of a new biostimulant obtained from slaughterhouse sludge by enzymatic hydrolysis processes used in the bioremediation of a soil polluted by the oxyfluorfen herbicide.

Currently, the use of biostimulants is widespread in sustainable agriculture because they represent an alternative to chemical fertilizers. In this manuscript, we investigate the response of a greenhouse tomato crop grown in pots to a biostimulant obtained from slaughterhouse sludge applied continuously to the substrate under which the tomato crop was grown or applied directly via the foliar route. Two doses of biostimulant (0.7 and 1.4 g L−1), applied four times throughout the crop growth period (120 days), were used. During this period, the height of the plants, number of flowers and number of fruits obtained were measured. After 90 days of the growth period, the nutrient contents in leaves as well as the chlorophyll a and b contents were analyzed. For fruits, nutrient and lycopene contents were determined, and the equatorial diameter and average fresh and dry weight were measured. The results indicate a higher content of nutrients and chlorophyll a and b in the leaves of plants treated with the highest dose of biostimulant and applied continuously to the substrate. This higher content of photosynthesis pigments in the plant is possibly responsible for a greater absorption of N by the plant and, consequently, for better growth.

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