Microbial community response to drought depends on crop

Growing season drought can be devastating to crop yields. Soil microbial communities have the potential to buffer yield loss under drought through increasing plant drought tolerance and soil water retention. Microbial inoculation on agricultural fields has been shown to increase plant growth, but few studies have examined the impact of microbial inocula on plant and soil microbial drought tolerance. We conducted a rainout shelter experiment to test how crop (corn vs. soybean) and microbial inoculation alter the response of soil microbial composition, diversity, and biomass to drought. The effects of drought on soil bacterial composition depended on crop type, while drought decreased bacterial diversity in corn plots and drought decreased microbial biomass carbon in soybean plots. Microbial inoculation did not alter overall microbial community composition, plant growth or drought tolerance, despite our efforts to address common barriers to inoculation success. Our study demonstrates that field studies that include multiple interacting factors are needed to understand how microbes will mediate plant responses to environmental stress.