Deer are the leading cause of crop damage by wildlife in Maryland, with most recent government estimates showing approximately $10 million in losses annually, with 77% of those losses attributable to deer (USDA NASS 2011). Maryland in particular faces greater challenges than many other soybean growing areas in the country due to smaller field sizes that are more often interspersed with and bordered by forested areas that provide refuge for deer, which emerge to graze highly palatable and nutritious soybeans. Farmers have regularly identified deer and wildlife damage as one of their top concerns, and frustrations by farmers are well documented in news media articles. Soybean yields in 2020 in certain fields at the Wye Research & Education Center in Queenstown, MD, were reduced by 20-30 bushels per acre in a field bordering a forested area. While hunting and crop damage permits allow some farmers to reduce deer population densities, some locations are not amenable to this due to factors such as landowners or neighbors that do not allow hunting, nocturnal grazing activity, and time required to harvest sufficient numbers of deer.

Research funded by the Maryland Soybean Board in 2021 suggested that soybean plants are extremely resilient to moderate grazing once established, however, we noted significant losses of individual plants at the earliest growth stages from emergence to the cotyledon stages.

We seek to evaluate the effect of planting soybeans into green cover crops as a mechanism by which early soybean losses due to deer and rabbit grazing may be reduced. We seek to test whether planting into different cover crops consisting of preferred deer forages will reduce grazing on young soybean plants and ultimately increase plant survival and yields. We are partnering with Dr. Weil to provide insights into his ongoing research on the value of planting into green cover crops to reduce fertilizer requirements.

We have prepared a randomized complete block design of five cover crop mixes on a field that experiences deer grazing and have placed trail cameras on each of the crop mixes to quantify deer grazing activity by varieties (Fig. 2). We have planted four mixes that qualify for the Maryland cover crop program payments: Austrian winter pea/wheat; clover/wheat; rape, and wheat. We have also planted turnips, which have been described as a preferred deer forage in
many parts of the Eastern Shore. We will conduct a randomly selected burndown of half (lengthwise) of each of the plots at 3 weeks before planting, and leave the other half of cover crops green until the first trifoliate emergence We walk the center row of each plot and perform a stand count and count deer or rabbit damage to seedlings in each plot’s center row weekly for approximately one month after germination in both treatments (conventional burndown vs late burndown) and record herbivory and death of all individual seedlings. To assess damage of the entire field and plot, we will take high resolution drone imagery of the plots to potentially quantify plant emergence and damage. We will implement deer and rabbit-proof exclosures on each plot to document soybean plant potential without deer and rabbit grazing.

We will document deer activity and herbivory in each of the plots with camera traps and we will use a thermal imaging camera mounted on a drone to test the applicability of using this approach to measure populations and quantify broader scale deer activity and populations in the area. We propose flying approximately 6-12 evening flights on a pre-determined survey path along field edges near forest cover to determine the applicability of using drone sampling as a method to detect deer populations and activity in agricultural fields. Multiple flight data will provide us the opportunity to assess variability in deer activity and better understand the pre-requisite number of flights needed to determine a deer population estimate for a given area.

Finally, will measure soybean yield at harvest time and compare them to the treatments. We will also sample cover crop biomass in December and at planting time to estimate the biomass produced by cover crops.

Update:
Cover crops were terminated using crimper. Soybeans have been planted into uncrimped and crimped cover crops. Planting occurred after cover crops self-terminated, but we will continue to test for differences in yields in fields with and without crimping.

Update:
All soybeans were harvested and yield data collected. Initial review of yield differences based on cover crop types appeared inconclusive, and a redesign of harvest approach for increased precision is needed. All trail camera images have uploaded into database and classified for analysis of deer preferences between cover crop types. Analyses are underway. We are presenting results at the Southeast Deer Study Group in Baton Rouge on February 26. We have engaged with two UMD undergraduate students in analysis of this data.

Update:
This study was hampered by delayed planting that led to cover crops senescing prior to planting. Planting into self-terminated cover crops did not appear to affect harvest rates in different plots. Deer seemed to prefer crimson clover/winter wheat mix in April, suggesting deer management efforts could be particularly effective hunting over that cover crop mix.

View uploaded report