One of the many benefits of cover crops is they let growers reduce nutrient runoff and help improve water quality in local watersheds. However, in some cases farmers may need to terminate covers and using herbicides is often the go-to method.
A new report analyzing water quality data from 2007-2018 by retired scientist Nat Shambaugh, who formerly worked for the Vermont Agency of Agriculture, Food & Markets on water monitoring, showed an improvement in reducing phosphorus runoff — directly attributed to the adoption of cover crops.
However, the data found an increase in herbicides being applied in Vermont, which could potentially run off into waterways that lead to Lake Champlain. Statewide data found that 35,000 pounds of glyphosate are spread annually in Vermont — a steep increase from the early 2000s when only 5,000 pounds of glyphosate were used annually.
Glyphosate is the herbicide of choice for many growers. According to the 2021 Cover Crop Benchmark Study, 79% of growers use herbicides to terminate their cover crops. Out of those growers who use herbicides, 94% use glyphosate.
Although glyphosate does break down after application, it’s unclear whether herbicides being used for cover crop termination are running into Lake Champlain. The U.S. Geological Survey will study glyphosate levels flowing into Lake Champlain from its tributaries.
Herbicides are certainly an important tool to manage cover crops in a timely manner, because failing to do so could produce other problems, such as tying up nitrogen or using too much moisture ahead of cash crops.
As increasing numbers of consumers are paying attention to how farming practices impact the environment, and legislators are encouraging cover crop adoption, it is becoming even more critical for growers to think through each choice they make for their farming operation and its impact.
As a hedge against environmental scrutiny in farming, it might be a good idea to explore ways to decrease herbicide use by utilizing different termination methods, such as roller crimping, grazing, mowing or even choosing cover crop species that will winterkill.
Should glyphosate one day face more strict controls or an outright ban in the U.S., having experience with these other termination methods will help you adjust — while at the same time, contributing to cleaner watersheds locally and possibly enhancing the bottom line as well.