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Research Highlights

Research Highlights
Evaluating Forage Soybeans as a Biological Fence to Reduce Deer Damage

2019 soybean yield map from a partner farm showing very low yield along tree lines due to heavy deer damage. Photo: University of Maryland

By Laura Temple

Wildlife damage – particularly from deer – has become a top challenge for many soybean and grain farmers, especially in fields near woodlands. Surveys estimate that deer cause crop losses of $100 million annually.

“Deer damage in this area is extremely heavy,” says Cory Atkins, who farms near Seaford, Delaware, and serves as a director for the Delaware Soybean Board and the United Soybean Board. “Deer damage is just as bad as weed pressure – and deer bring additional weeds with them. It seems like deer pressure gets worse every year.”

Traditional deer management strategies for farmers include hunting, fences and repellent. For example, Atkins relies heavily on hunting to manage populations. However, licenses, permits and varying regulations on public and private land can limit hunting. Fencing and repellent both require significant time and resource investment.

“As farmers, we’ve repeatedly asked state officials for help with this problem,” Atkins says. “We chose to fund research with the soy checkoff to do our part to find solutions.”

Soy checkoff support from both the Delaware Soybean Board and the Maryland Soybean Board is funding research of an alternative management strategy – biological fencing. Planting a crop that deer prefer along field borders could reduce damage to the rest of the field. Research on this option is being conducted by a team including Extension agronomists and wildlife specialists from the University of Delaware and the University of Maryland, plus Department of Natural Resources representatives from both states.

“Developing additional tools to manage deer feeding in crops will benefit all farmers in our region and beyond,” says Nicole Fiorellino, University of Maryland Extension Agronomist who has been involved in the research project. “Forage soybeans have potential to be used as a ‘deer fence’ on the borders of fields to protect yield in the majority of the field. And our learnings will apply to addressing other types of wildlife damage.” 

The concept for this research is based on observations of deer feeding on forage soybeans. Objectives are to compare yield losses between unfenced and biologically fenced soybean plots and to investigate the causes of deer preferences for specific soybeans.

“We are trying to answer several questions,” says Fiorellino. “Can we grow forage soybeans? Will deer like them? How much deer pressure can they help manage? How wide does the forage soybean ‘fence’ need to be? And many others.”

The scientific study aims to quantify the efficacy of biological fences and provide guidance to farmers about how this tool could fit into an overall deer management strategy. Proof of concept research began in 2018. In the following years, research focused on both the agronomics of forage soybeans and further observation of the potential for biological fencing to reduce damage in fields.

“Eventually we would like to develop a decision tool that could provide farmers with guidance based on deer pressure, field size, field location and other factors to make a biological soybean fence a practical option to reduce deer damage,” she explains.

Fit for forage soybeans

Past research and observation found that deer preferentially forage on soybeans because they can feed on plants from the fourth trifoliate until the late reproductive stages. During that time, soybeans are easy to digest and provide an excellent source of protein.

Forage soybean varieties emphasize overall feed value of the plants more than just yield. These varieties regrow after grazing, like other types of forage, sometimes even more vigorously than at first. That regrowth supplies more nutrition with less effort, theoretically keeping deer from wandering farther into fields.

“The primary forage soybean we looked at has been a Group 7 maturity,” Fiorellino explains. “That’s a much longer-season soybean than the Group 4 to 5 soybeans typically grown in this area. We learned that they grow well and seem to keep some of attention of the deer.”

However, she says that 2021 research will include a broader range of forage and specialty soybean maturities because cooperating farmers expressed interest in options that mature with the rest of their crop. That would increase the chances of getting some yield from the fence area to help offset seed costs. 

Tracking deer behavior

Can this approach protect yield? Atkins has participated in field trials, and he observed that the forage soybeans helped reduce pressure in soybeans, though he didn’t see much benefit around corn fields. 

His were among several fields in Delaware and Maryland that used a partial perimeter of forage soybeans compared to conventional soybeans. In 2018, the researchers felt they didn’t have enough deer pressure. Trials in 2019 were intentionally located near known high deer populations, and overgrazing on emerging forage soybeans kept some trials from getting fully established. 

Fiorellino says the next step of the research is to better understand and quantify deer behavior so that guidelines can be developed based on concrete data, rather than just casual observation.

“The next stage of research, led by our wildlife specialist, will include deer cameras in research plots,” she says. “We plan to offer deer a buffet of soybean variety options and then record their feeding behaviors.”

As more data is collected, the research team expects to better understand deer preference for soybean types. They will also calculate profit margins for biological fencing with soybeans. Together, that information will lead to practical guidance to reduce deer damage in soybean fields and other crops.

This project was funded by the soybean checkoff. To find research related to this research highlight or to see other checkoff research projects, please visit the National Soybean Checkoff Research Database.