Discussing how to nurture resilience in grasslands as part of the 2024 NOFA-Vermont and the MOFGA Climate Forums was Jaime Garzon. Garzon is an assistant Extension professor and dairy forage educator at the University of Maine Cooperative Extension.
A Different Perspective on Soil
“People, when they imagine grasslands, they imagine something that is very homogeneous. That you have one plant that is growing in the pasture, maybe some trees, and some animals,” Garzon said. “But actually what is happening is an interaction between many factors: soil, air, animals and plants.”
There is currently a shift in agronomic thinking (long recognized by organic growers) that soil is part of a broader ecosystem that sustains not just plants but also animals – and the humans that consume those animals. Instead of talking simply about soil characteristics (water holding capacity, texture, chemical composition and aeration), it’s important for grassland managers to also consider nutrient cycling, microorganisms, carbon sequestration and nitrogen fixation.
According to Garzon, there are economic benefits that come with thinking about grasslands and their soil in a more holistic way including healthier plants which can translate to higher forage yields and better quality. Another potential benefit is a reduced risk of loss to environmental stressors.
“Soil health can better prepare us to cope with the unexpected,” he said.
Forage Budget & Quality
Whether grazing or putting up stored forage, it’s important to consider the approximate biomass of the grass that is being harvested and its nutritive value. In order to avoid buying forages, the harvest must be matched with the number of animals on the farm, the average weight and the animals’ physiological needs.
Garzon believes strongly in forage testing at a lab, and had some specific recommendations for forage quality metrics. For protein, the goal is to have at least 7% but the ideal would be 10% protein or even higher.
Fibers – neutral detergent fiber (NDF), acid detergent fiber (ADF) and lignin – are other indicators of forage quality. “With the NDF, if you go higher, it could be a problem. Usually what is expected is that you should not go higher than 60%. If you go higher, that means you are producing more fiber than soluble nutrients,” Garzon said.
Conversely, with total digestible nutrients (TDN), higher is better. The ideal is 70%. Mineral quantities will vary depending on what animal is being fed.
Garzon also believes in the proper storage of dry hay. “I saw those bales in the middle of nowhere getting rain, getting moisture, and by doing that, it’s an excellent way to lose money because all the effort that you are doing will be lost because that bale that is not protected is losing quality,” Garzon said.
He recommended wrapping dry hay in silage film if barn storage is not an option.
Jaime Garzon is an assistant Extension professor and dairy forage educator at the University of Maine Cooperative Extension. Photo courtesy of Jaime Garzon
Species Selection
With so many different species and varieties available for grasslands, the first consideration should be to establish a planting objective while taking into account soil types. The soil characteristics that are necessary for making an appropriate species selection include slope, pH, moisture, drainage and concentration of nutrients (based on soil testing).
“There are some plants that are better adapted to neutral soils but can stand acid soils. There are plants that can tolerate high moisture or high drainage. You need to choose which is better for what you need,” Garzon said.
For growers with acidic soils, he mentioned forgoing alfalfa. Alfalfa will not grow if the pH is below 6.5, and although applying lime is an option, Garzon doesn’t think the cost and time can be justified.
“Trying to adapt your farm to a specific species is not an appropriate perspective. It is better to adapt the plant that is available to your soils,” he said.
Legumes like alfalfa are important from not just a nutritive perspective but an ecological one as well. Legumes provide nitrogen fixation, increase litter decomposition and help to regulate greenhouse gases. Having legumes comprise 30% of the canopy is the current recommendation for both pasture and hay ground. This percentage of legumes can provide 50 lbs. of nitrogen per acre, which is the minimum amount of nitrogen a forage crop needs.
No-till seeding and frost seeding are two ways to increase the percentage of legumes in a stand. Garzon reminded growers that frost seeding only works when the nights are below freezing but the days are not.
“You need ice to open cracks in the surface of the soil, but later on in the day that ice gets transformed into water to have that moisture that the seeds need to start growing,” he said.
For cool season perennials, Garzon suggested fescues, timothy, orchardgrass, alfalfa (when appropriate) and clovers. For cool season annuals, he promoted triticale, oats and rye. And for warm season annuals, he said sudangrass, millet and crabgrass (for horses).
Frequency & Intensity of Harvest
Frequency refers to how often grassland is harvested. Garzon’s main recommendation is to start harvesting when seed heads start to appear. The goal is to harvest when there is enough volume but before the fibers begin to increase and the protein and palatability begin to decline. If the stand is not homogeneous the best time to begin harvesting is when 30% of the field has seed heads.
Intensity refers to when to stop harvesting, either with grazing animals or with machinery. Garzon said to aim for leaving four inches of stubble for grass and seven for legumes.
“Grasses need to preserve some growing points where they still have sugars, where they still have food to regrow. By going too short, you are decreasing the performance of your grasslands for the next cut and maybe for the next year,” he said.
If the plants in a grassland stand don’t have enough time and nutrients to regrow, other plants will begin to take advantage of the situation. Perennial weeds will first appear, followed by wood species which will increase the acidity, further degrading the stand.
by Sonja Heyck-Merlin
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