Project Details:

Reducing Deer Damage to Soybeans using Forage Soybeans as Biological Fencing

Parent Project: Reducing Deer Damage to Corn using Forage Soybean as Biological Fencing
Checkoff Organization:Delaware Soybean Board
Categories:Soybean utilization, Insects and pests
Organization Project Code:
Project Year:2019
Lead Principal Investigator:Nicole Fiorellino (University of Maryland)
Co-Principal Investigators:
Nicole Fiorellino (University of Maryland)

Contributing Organizations

Funding Institutions

Information and Results

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Project Summary

Deer damage has become a national, natural hazard to crop producers. It has been estimated that a total of $100 million loss on agricultural crops is caused by deer annually in the United States ( Ober, et al. in 2014 reported that 9.6% of soybean acreage in North Florida was damaged by deer, causing estimated value of $1,458,959 loss. Mid-Atlantic farmers also complain about deer damage. Some fields cannot be used to grow soybean anymore because of recurring extensive deer damage.

Many states in the United States have published deer management programs on their government websites, and extension specialists at some universities have studied and suggested deer damage control strategies. Hunting, fencing and repellent are the three main management strategies; using the combination of two or more methods may be the most efficient to reduce deer damage. However, all of those strategies need investment of materials, labor and farmers’ time. The use of a biological fence with traits that appeal to deer is considered the most cost-effective solution to reduce deer damage on crops.

One example of this strategy is the soybean research field at Kentland Farm, VA. It has been protected by a soybean fence for the past two years. We observed that deer feed on these fencing plants, but no scientific study has been conducted to quantify the efficacy of the strategy. Our hypothesis is that deer-appealing soybean varieties should include, new growth, higher sugar, and exceptional biomass with transgenic traits for transgenic soybean fields. Once the hypothesis is confirmed, we will develop a producer-friendly protocol that employs protective rows around soybean fields such as number of rows. Our deer-appealing varieties should be the best solution to reduce deer damage with easy implementation and a low cost. It is expected that these varieties will benefit all soybean growers in the Mid-Atlantic area because the fencing is being employed simply as deer-food rows, so a particular maturity and yield are not as important.

“Soybean is the most popular item on a deer’s menu” - Deer readily and preferentially forage on soybeans because they can feed on plants showing the fourth trifoliate leaves until the late reproductive stages. For several months, soybean leaves and young stems are easy to digest, and soybean is an excellent source of protein (Loos, 2013). Maryland farmers suffered more than $7 million from deer damage in 2013 (, and this economic loss has not been reduced. 2016 was a drought or semi-drought year for many counties in Maryland, so the crop profit margin was tight, causing farmers’ less tolerance to deer damage. Joel Steinman in northern Dauphin County near Halifax estimated $20,000 loss by deer ( In order to reduce the crop damage, some farmers either become hunters themselves or become big fans of deer hunters (Blanton, 2007; Loos, 2013). Complications from hunting are apparent. For example, Glenn Miller, another farmer from northern Dauphin County who farms 1,000 acres, didn’t want to shoot deer eating soybeans in the middle of his soybean field because dragging dead deer out would cause even more damage (

Hunting is not the only way to regulate deer - Hunting may be the most feasible and economic way to keep the deer population stable, but other control methods are also necessary to manage deer damage. Two popular ways to reduce deer damage are fencing and repellent. A single strand of electric fencing at 2 feet tall deer’s fear of electric shock or odor to reduce their access to fenced field, and an electric fence can be solar powered (Woods, 2015). However, deer often become adapted to the fence and develop fence tolerance, so crop damage continues (Dixon, 2002). Repellents have also been used to reduce deer browsing, but these have to be reapplied after rain (Pierce and Wiggers, 1997). Using integrated damage management, one or more methods together, may be the best way to control the damage. Thus, farmers need to learn management techniques such as fence installation and maintenance as well as incur the associated costs of damage control on their own fields.

Deer appealing vs. unappealing soybean varieties - There is no any published information about soybean varieties preferred by deer, but deer do choose varieties to browse according to breeders and growers’ field observation. For example; we grew two soybean varieties as a fence at the crossing block at Moore farm, Blacksburg Virginia in 2015. One variety was badly damaged by deer, but the other one was rarely touched. Deer also have their own paths to eat in the field. Bryan Taliaferro, Virginia soybean grower, claimed that deer browsed on one section of his field where the same variety that was browsed at the Moore Farm was grown. Acorn is also a favorite food of deer. Deer prefer white oak acorn more than red oak acorn because white oak acorn is less bitter than red ones ( Therefore, soybeans with appealing leaf compounds might divert deer’s attention. Deer often show a preference for natural and agronomic forage type soybeans, hence we assume that continually growing, large leaf, and higher sugar content of soybean varieties would be browsed heavily, but we haven’t tested the sugar content in soybean leaves because we only test sugar content in seeds.

Project Objectives

The overall goal of this study is to provide an easy and effective solution to reduce deer damage to crops through protective rows that would be preferred fodder. There are two specific objectives: 1) To compare the yield loss of unfenced grain type soybean plots versus grain soybean plots surrounded by biological fencing and 2) To investigate the cause of deer preference for forage soybean by measuring concentrations of sugars in the foliage of forage soybean and grain type soybean. Note that this will be the second year of performing this research. We plan to use a similar field design in 2019 as we used in 2018.

Project Deliverables

Primarily, two treatments will be conducted: no fence in a traditional RR soybean grown for grain as positive control, and a "biological fence" using forage type soybean with RR trait that could be used for RR soybean growers. Three replications of each treatment will be applied on each field. The RR soybean for grain will be harvested when mature. The yield of each plot will be recorded to compare the effect of biological fence. Our hypothesis for objective 1 is that plot yield with biological fencing is significantly higher than the plots without fencing. Our hypothesis for objective 2 is that concentrations of sucrose, glucose, and/or fructose will be higher in the foliage of forage soybeans compared to soybeans grown primarily for grain.

Progress of Work

Updated November 20, 2020:
Objective 1:
• Six large scale fields were planted using a partial perimeter of forage soybean vs. non-forage soybean. Four were planted in Delaware while three were planted in Maryland.
• The same forage soybean variety was used in 2019: Eagle Brand “Big Fellow”, (indeterminate, high number of nodes, maturity group VII).
• Small variety trial conducted at Beltsville Research and Education Center to compare yield of forage soybeans to agricultural soybeans.

Objective 2:
• Foliar sugar content measured for varieties tested.

Final Project Results

Updated November 23, 2020:

View uploaded report PDF file

Forage soybean yield on farms - Complete crop loss of the forage soybean due to deer overgrazing was observed on several of the fields in 2019. Project PI’s were disappointed with results in reducing deer damage in 2019 compared to 2018. Because we felt that we did not have enough deer pressure in 2018, we intentionally put the trials in areas of known high deer populations, leading to grazing of the forage soybeans at or near emergence, inhibiting the plant’s ability to establish itself. This is demonstrated in Figure 1, showing the extremely low yields in the areas of this field near treeline border. A possible factor in the difference between 2018 and 2019 is that all of the trials in 2019 were planted earlier then in 2018.

Because of the disappointing results in 2019, investigators at University of Delaware are conducting a demonstration project on double crop beans using deer repellant to provide the forage soybeans a chance to emerge and establish themselves prior to heavy grazing by deer. It may have been beneficial to apply deer repellent on sprayed our forage beans with deer repellant to buy them time.

Variety Yield, bu ac-1 (mean ± standard error)
73P93R 34 ± 3 a
7447XTS 26 ± 3 bc
AG48X9 31 ± 4 ab
BigFellow 14 ± 2 d
S53-F7X 25 ± 3 c
V12-4590 17 ± 1 d

Soybean yield at Beltsville REC – Six varieties, including one forage soybean variety (BigFellow) were evaluated for yield and sugar content in 2019. Yield measurements below demonstrate the low yield observed in the BigFellow forage soybean variety compared to the rest of the agricultural soybean varieties. The BigFellow performed similarly to V12-4590 variety, however this variety was planted extremely late and its yield potential was likely limited due to this.

Foliar sugar content – Compared to last year, the foliar sugar content data was not as straightforward. The forage soybean did not have increased total sugar content at any sampling time period compared to agricultural soybeans, nor did it have increased content of the different sugar forms (fructose, glucose, or sucrose). The V12-4590 variety that was planted quite late had higher fructose concentration at the third sampling time period than any other variety evaluated. Further research should identify which sugar type is most attractive to deer and if a later planting date might increase that sugar content enough to divert deer from commodity soybeans.

Benefit to Soybean Farmers

There will be two primary benefits to soybean farmers. 1) The margin profit of each plot with differing fence treatments will be calculated based on the yield of soybean plots plus the cost of biological fences and subsequent yield of remaining undamaged soybean yield. Our hypothesis is that the margin profit of soybean fenced plots are significantly higher than the plots without fence. 2) The mode of action causing deer preference for forage soybean will be elucidated. Our hypothesis is that concentrations of sucrose, glucose, and/or fructose will be higher in the foliage of forage soybeans compared to soybeans grown primarily for grain. One the mode of action is determined, then biological fencing relying on similar properties can be further tested and applied in other agriculture production such as vegetable in order to maintain on-farm income.

Performance Metrics

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