The Effect of Long-Term Glyphosate Application On Soil Microbial Communities in a Soybean, Corn Crop Rotation: A Greenhouse Study.

Farmers have observed a reduction in corn and soybean yields in glyphosate resistant corn and soybean cropping systems. Previous researches suggest a possible shift in soil biological communities resulting from long-term glyphosate application. We conducted a greenhouse study to determine possible relationships between glyphosate use and its effects on soil microbial communities by using ¹³C labeled glyphosate. Two glyphosate formulations (Powermax/Monsanto and Cornerstone/Agrisolutions) were spiked with ¹³C glyphosate. Corn and soybean were grown in rhizoboxes and glyphosate applied multiple times each year. Soil samples were collected from the rhizoboxes and soil community analyzed by phospholipid fatty acids (PLFAs) profiling and real-time PCR using Fusarium-specific primers. Information from our research will increase our understanding of the effect of glyphosate applications on soil microbial communities in glyphosate resistant cropping systems.