Project Details:

Evaluating Deer Preferences for Soybean Varieties and Soybean Response to Deer Herbivory

Parent Project: Evaluating soybean variety performance and response to deer grazing
Checkoff Organization:Maryland Soybean Board
Categories:Environmental stress, Insects and pests, Crop management systems
Organization Project Code:22062921
Project Year:2022
Lead Principal Investigator:Luke Macaulay (University of Maryland)
Co-Principal Investigators:
Nicole Fiorellino (University of Maryland)
James Lewis Jr (University of Maryland)

Contributing Organizations

Funding Institutions

Information and Results

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Project Summary

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.

In 2021, we engaged in research to better understand deer preferences and plant response in heavily damaged agricultural fields. The study found a surprising performance of a less expensive Group 4.7 forage soybean, GT1 Brier Ridge from Lacrosse Seed as one of the higher performing varieties just after a Group 5.3 conventional soybean. These yields were considered by the farm manager as one of the best yields he’s observed out of these fields in many years.

A forage analysis of all the varieties in early September 2021 suggested that levels of crude protein and dry matter may have driven preferences for a late maturing soybean variety, however, camera trap data from 2021 suggested that deer preferences may be tied to maturity group as data suggests a move from earlier varieties (Brier Ridge, Biologic, and conventional Pioneer Group 3.1 beans) to later varieties (Big Fellow, and Pioneer Group 5.3 beans) as the growing season progressed. In this proposal, we propose conducting more regular forage analysis (every 3-4 weeks during the growing season) to determine if forage quality changes with different varieties over time.

Project Objectives

Ongoing research has provided baseline information about the applicability of using various varieties of forage soybeans as a diversion crop around a field perimeter to reduce damage to core growing areas. This project seeks to continue that work and gain deeper understanding across a second growing season by continuing to assess 1) yield by different forage
soybean varieties and 2) deer activity and preferences of these varieties. We seek to add to the project by 1) conducting regular forage analyses across the growing season to discern whether deer prefer certain varieties at certain times; 2) conducting a manual defoliation experiment to better understand soybean plant response to herbivory, and 3) providing a greater quantity of demonstration seeds to farmers and assessing their qualitative and quantitative observations about the practice.

Project Deliverables

We will focus the experimental effort at the Wye Research & Education Center, using a randomized complete block design on approximately five-seven soybean varieties in fields bordering forested areas with long-term historical deer grazing pressure. We will place a 5-10’ diameter hog-wire deer exclosure on each plot to asses yield potential in the absence of grazing.

We will expand the use of trail cameras to quantify deer grazing activity by different soybean varieties to gather improved information on deer preferences and activity across multiple replicates.

We propose planting the following varieties in a strip plot design:
1. Conventional Group 3.5 soybean - control
2. Group 4.7 forage soybean – GT1 Brier Ridge
3. Group 7 forage soybean – Big Fellow Eagle Seed brand
4. Group 6 forage soybean – Biologic
5. Conventional Group 5 soybean

To better understand soybean plant response to deer grazing, we plan to conduct a controlled herbivory simulation in a deer-proof fenced enclosure at the Wye Research & Education Center. We propose planting approximately 90 plants of each variety and leaving 30 without defoliation, 30 with weekly light defoliation (~33% defoliation), and 30 with weekly heavy defoliation (~66% defoliation). We will use weekly defoliation, which is consistent with observed deer grazing in 2021 that appeared to occur in heavy bouts approximately every 5-7 days. We plan to conduct this on the same five varieties that we will be testing in our strip plot design. We will sample a subset of plants for biomass at the R6 /R7 stage, when leaves begin to yellow, and harvest the rest of the plants for yield at normal harvest time.

We will conduct wet chemistry forage analysis every 3-4 weeks of the varieties we test in the study by clipping new leaf growth in the morning (when sugars are highest in plant tissue) and immediately placing samples them in a Styrofoam cooler with ice packs until they can be frozen at the research lab and mailed to a forage analysis lab.

Finally, we have reserved a large portion of the budget to provide demonstration seeds of forage varieties at a collaborating farmer’s fields on the Eastern Shore to evaluate performance of these varieties in different soil types and with different deer population characteristics. We will prioritize provision of demonstration seed to farmers who have a history of yield-monitor data on proposed fields of planting to compare before and after effects of buffer treatments.

Progress of Work

Updated July 19, 2022:
We have planted two fields with forage soybeans. Weeds have been sprayed. ~32 cameras are monitoring deer use of each variety. Experimental clipping to simulate deer grazing is underway. We are clipping biomass every 1-2 weeks, and taking forage samples every other clipping.

Updated February 3, 2023:
All soybeans were harvested and yield data collected. All trail camera images have uploaded into database and classified for analysis. Preliminary 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.

Final Project Results

Benefit to Soybean Farmers

Performance Metrics

Project Years