White-Tailed Deer Browsing of Soybeans Significantly Changes Plant Morphology and Reduces Yield, Contributing to Large Financial Losses

Abstract

White-tailed deer (Odocoileus virginianus) densities in North America have increased significantly in the last 100 years, contributing to extensive agricultural losses. Smaller farming operations are more likely to be impacted by these losses since they generally are not as financially buffered against poor harvests. This study explores changes in plant growth patterns, percent damage, harvest biomass, and yield of a soybean crop from deer browsing at three exposure levels on a small research farm in southwestern Ohio. Experimental soybean plots protected from deer browsing were placed in 0.5 hectare fields during the entire 2010 growing season. Similar, but unprotected, control plots were adjacent to these exclosed areas. The exclosure/control areas were assigned a browse exposure level (high, medium, low) based on their proximity to a wooded area. Individually identified plants were sampled by exposure level and treatment (protected vs. unprotected) in July and August measuring height, width, and percent damage. Yield and above-ground biomass were assessed upon harvest in October. Soybean plants protected from deer browsing were 25 percent taller, 87 percent less damaged, yielded 74 percent more seed, and had 47 percent more above-ground biomass than unprotected plants. Browsing exposure level was not significantly different between enclosed and open plots for any plant parameter. Given per-plant yield results and an average planting density, this farm experienced a loss of $68 (±$32) per hectare to deer. Overall, that represents a $405 (± $214), or 43 percent, financial loss over one growing season.