ProGro BIO, Inc. has released findings from new independent research confirming that Rhizol®, its flagship microbial soil inoculant, delivers measurable improvements in soil health, nutrient retention, and crop nutrient uptake under real-world farming conditions. The study, based on the analysis of more than 1,000 independently tested soil samples, provides strong third-party validation of benefits widely reported by growers using the product.
The research was conducted by the Agronomics Division of the North Carolina Department of Agriculture & Consumer Services (NCDA & CS). Soil samples were collected from both Rhizol-treated and untreated field sections before planting and after harvest, allowing for a comprehensive assessment of nutrient dynamics across the growing season.
Stronger Nutrient Retention in Soils
A key focus of the study was the nutrient index, a metric used to estimate the likelihood of essential nutrients—such as phosphorus, potassium, sulfur, and nitrogen—being lost from soil through leaching, volatilization, or runoff. Lower nutrient-index values indicate stronger nutrient retention.
While pre-planting nutrient variability was similar across treated and untreated plots, post-harvest results showed consistently lower nutrient-index values in Rhizol-treated soils. This indicates that more nutrients remained in the root zone, reducing loss risks and improving the efficiency of applied fertilizers.
Increased Organic Matter and Soil Nitrogen Potential
The research also revealed a statistically significant increase in humic matter (HM%) in soils treated with Rhizol. Higher humic matter levels are widely recognized as indicators of improved soil fertility, structure, biological activity, moisture-holding capacity, and nitrogen availability.
According to the findings, these improvements are linked to Rhizol’s ability to enhance biomass production, stimulate beneficial microbial processes, and promote the formation of stable organic matter fractions. For growers, this translates into soils that are more productive, resilient, and consistent over time.
Improved Nutrient Uptake by Crops
To assess how improved soil nutrient retention affects crop nutrition, ProGro BIO also conducted multi-location plant tissue analysis, independently processed by Waypoint Analytical in Memphis, Tennessee. Results showed that crops grown in Rhizol-treated soils consistently exhibited higher tissue concentrations of essential nutrients compared to untreated controls.
Enhanced nutrient uptake supports early crop vigor, stronger stands, improved stress tolerance, and higher yield potential—particularly under variable environmental conditions.
Supporting Productivity and Sustainability
Commenting on the findings, ProGro BIO emphasized that the results underscore Rhizol’s value as a season-long soil and nutrient management tool, especially at a time when fertilizer costs remain volatile and environmental regulations are becoming more stringent.
The company noted that by improving nutrient efficiency and soil performance, Rhizol helps growers get more value from applied inputs while supporting responsible nutrient stewardship.
The independent data reinforces Rhizol’s role in helping farmers build healthier soils, reduce nutrient losses, and maintain productive cropping systems, aligning agronomic performance with long-term sustainability goals.
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