A Framework for Simultaneously Assessing Soil-Applied Amendment Effects on Root Symbionts
Faculty Mentor Information
Dr. Edwin Lewis, University of Idaho
Presentation Date
7-15-2026
Abstract
Agricultural amendments are commonly applied to managed soils to improve crop performance; however, their compatibility with mutualistic root symbionts is a generally understudied aspect of product evaluation. Rhizobia and arbuscular mycorrhizal fungi (AMF) are two of the most significant of these symbionts, enhancing a plant's capacity for nitrogen fixation and phosphorus uptake from the soil. While the individual effects of amendments on each symbiosis have been studied, no standardized methodology exists for evaluating a soil-applied amendment's effects on both associations simultaneously. Here, we propose a framework for assessing soil-applied amendment compatibility with both AMF colonization and rhizobial nodulation. As a model system, we use a naturally derived biostimulant product extracted from black walnut (RDX-N,Redox Bio-Nutrients, Burley7, ID). Effects were assessed across two host systems, tomato and common bean, using existing quantification methods adapted for each host system. RDX-N treatment resulted in no significant difference in AMF colonization and rhizobial nodulation as compared to untreated controls. As the adoption of new agricultural amendments increases, this study provides a replicable framework for evaluating the compatibility of any soil-applied amendment with beneficial soil microbiota.
A Framework for Simultaneously Assessing Soil-Applied Amendment Effects on Root Symbionts
Agricultural amendments are commonly applied to managed soils to improve crop performance; however, their compatibility with mutualistic root symbionts is a generally understudied aspect of product evaluation. Rhizobia and arbuscular mycorrhizal fungi (AMF) are two of the most significant of these symbionts, enhancing a plant's capacity for nitrogen fixation and phosphorus uptake from the soil. While the individual effects of amendments on each symbiosis have been studied, no standardized methodology exists for evaluating a soil-applied amendment's effects on both associations simultaneously. Here, we propose a framework for assessing soil-applied amendment compatibility with both AMF colonization and rhizobial nodulation. As a model system, we use a naturally derived biostimulant product extracted from black walnut (RDX-N,Redox Bio-Nutrients, Burley7, ID). Effects were assessed across two host systems, tomato and common bean, using existing quantification methods adapted for each host system. RDX-N treatment resulted in no significant difference in AMF colonization and rhizobial nodulation as compared to untreated controls. As the adoption of new agricultural amendments increases, this study provides a replicable framework for evaluating the compatibility of any soil-applied amendment with beneficial soil microbiota.