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Biological products often contain microbial inoculants and/or organic ingredients that are marketed as being capable of improving nutrient use efficiency and promoting sustainability through their impact on plant and soil health. However, there is lack of field research on their efficacy. A study was conducted in Johns Creek, Georgia, USA, to evaluate the effects of two biological products (BP1, BP2) on soil biological health and turf quality. A unique delivery system was used for applying the products directly in the root zone and for aeration. Soil biological health was evaluated by determining microbial abundance and function. Turf quality was expressed as % normalized difference vegetation index based on digital images of plots. The biological products did not significantly impact the soil health parameters that included abundance of ammonia oxidizers, soil respiration, urease, and phosphatase activities. Similarly, they did not have any significant impact on turf quality and health. This could indicate that the products' active ingredients were not effective under the study conditions. One possible reason is they were applied on the top of the standard inputs as recommended by the manufacturer, and that they were not addressing any limiting factor in the system. The only significant difference was between the two products in which subsurface application of BP2 resulted in higher abundance of ammonia oxidizers than surface application of BP2 and BP1. The study highlighted the need to evaluate the efficacy of biological products and to identify conditions under which they can be beneficial before they are extensively used. [ABSTRACT FROM AUTHOR]