Comparison of Soil Microbial Community Between Organically and Conventionally Managed Golf Courses Using Pyrosequencing-Based Metagenomics.

The rhizosphere of plants contains many beneficial microorganisms and nematodes involved in plant disease suppression by competition, antibiosis, and inducing host plant resistance, as well as organisms that cause disease. Golf courses are intensely managed by biological, cultural, and chemical controls, with the highest inputs on putting greens, then fairways, and lastly roughs.  These practices may affect soil microbe and nematode communities, which could in turn affect disease severity.  The goal of this study is to compare soil microbial and nematode communities between organically and conventionally managed golf courses and between management areas.  We sampled all three management areas on three golf courses located within 10 km of one another: one managed organically, one managed conventionally, and one “hybrid” course that uses both organic and conventional products.  Soil samples were systematically collected using cores and the samples were processed for nematode species counts, bacterial and fungal diversity and relative abundance by pyrosequencing, and soil nutrient and texture analysis.  Our preliminary results show significantly lower abundances of plant pathogenic nematodes on the organic greens compared to the other two courses, which correspond to a significant increase in the percent frequency of free-living nematodes found on the organic course.  Although less drastic, this similar trend was seen for the organic course compared to the conventional course on fairways and roughs.  An increase in soil organic matter correlated with an increase in plant pathogenic nematodes on the greens, whereas a decrease in soil organic matter correlated with an increase in bacteria feeding and animal feeding free-living nematodes.  We will further discuss comparisons of soil microbial communities between the golf courses and between management areas.