BACKGROUND:  Conservation practices often associated with glyphosate-resistant crops, e.g. limited tillage and crop cover, improve soil conditions, but only limited research has evaluated their effects on soil in combination with glyphosate-resistant crops.  It is assumed that conservation practices have similar benefits to soil whether or not glyphosate-resistant crops are used.  This paper reviews the impact on soil of conservation practices and glyphosate-resistant crops, and presents data from a Mississippi field trial comparing glyphosate-resistant and non-glyphosate-resistant maize (Zea mays L.) and cotton (Gossypium hirsutum L.) under limited tillage management. RESULTS:  Results from the reduced-tillage study indicate differences in soil biological and chemical properties owing to glyphosate-resistant crops.  Under continuous glyphosate-resistant maize, soils maintained greater soil organic carbon and nitrogen as compared with continuous non-glyphosate-resistant maize, but no differences were measured in continuous cotton or in cotton rotated with maize.  Soil microbial community structure based on total fatty acid methyl ester analysis indicated a significant effect of glyphosate-resistant crop following 5 years of continuous glyphosate-resistant crop as compared with the non-glyphosate-resistant crop system.  Results from this study, as well as the literature review, indicate differences attributable to the interaction of conservation practices and glyphosate-resistant crop, but many are transient and benign for the soil ecosystem. CONCLUSIONS:  Glyphosate use may result in minor effects on soil biological/chemical properties.  However, enhanced organic carbon and plant residues in surface soils under conservation practices may buffer potential effects of glyphosate.  Long-term field research established under various cropping systems and ecological regions is needed for critical assessment of glyphosate-resistant crop and conservation practice interactions.