Planting a cash crop into a standing, green cover crop is a relatively new practice with a range of reported benefits from correcting soil salinity to increasing organic matter and nutrient utilization. During the 2019 No-Till on the Plains Winter Conference, Natural Resources and Conservation educator Jay Fuhrer shared his experiences with planting green strategies.
At Menoken Farm, an agricultural research farm in Menoken, North Dakota, Fuhrer has had the opportunity to experiment with a wide variety of no-till and cover crop methods combined with multi-species grazing. Most commonly, Fuhrer’s planting green strategies focus on seeding canola or soybeans into rye, which overwinters in cool temperatures.
“Every green plant is a carbon inlet, so I’ve got an inlet all through the spring,” Fuhrer said. “Now we have the really low-carbon soybeans being offset with the higher carbon rye, so we have more food coming in to the system.”
The result of green seeding for Fuhrer is a never-ending release of exudates into the soil, from rye through soybeans or canola. Additionally, planting green provides continual soil coverage and more efficient water utilization.
“I want to transpire out water, not evaporate out water,” Fuhrer said. “When we evaporate out water, it costs us something, and when we transpire out water, it buys us something — there’s a big difference.”
When Fuhrer uses the phrase “armor up” to attest to the protective properties of planting green, it also conjures images of the challenges of planting in a thick, growing cover crop like rye. However, the reality of planting green, at least in Fuhrer’s experience, is exactly the opposite.
“The easiest seeding I’ve ever been around is planting green,” Fuhrer said. “There’s so much difference planting into a live plant.”
Planting green increases nutrient availability for plants, especially available nitrogen, Fuhrer said. In natural perennial field, one-third of the available nitrogen would be inorganic nitrogen, while two-thirds would be in organic form and more usable for plants.
In a continuous wheat field with no cover crop, the nitrogen makeup would be opposite — two-thirds inorganic to one-third organic. The goal of planting green and cover crop strategies is to use the natural nitrogen makeup as a template for cash crop fields.
“It’s the catch and release of nutrients,” Fuhrer said. “When we plant green, we have more nitrogen in the organic form, less in the inorganic form, and it goes into that green plant.”
Where a quick-killed cover crop experiences accelerated decomposition and an accelerated release of nutrients, green plants decompose slowly and release nitrogen back into the ground slowly.
“I want a slow release of nitrogen. I don’t want a huge amount when I’ve got a little seedling there,” Fuhrer said. “It makes out water quality issues a lot better, makes our nitrous-oxide scenarios a lot better for the atmosphere and it makes us more efficient.”
Everything Through A Stomach
The research on Menoken Farm focuses on species diversity above and below ground, hoping to increase the utilization of every aspect of the landscape. Fuhrer grazes yearling stock cattle and sheep simultaneously in order to increase carbon, soil aggregation, and erosion control and to combat salinity in the soil.
“I want the anaerobic portion of the biology that is inside of them, and I want the aerobic portion of the biology that is on the outside of them,” Fuhrer said. “Soils, plants and animals evolved together biologically so it makes sense to return to having them together.”
Fuhrer utilizes strip grazing to maximize efficiency and limit field damage. His general rule for measuring forage utilization is to gauge by weight rather than sight.
“When we look at the top and bottom portions in these plants, we have to ask where is the higher protein and where is the higher energy?” Fuhrer said. “It’s in the top half by weight so when we move into a paddock I like to nip off a plant, lay it on my hand, balance it and then I know where that 50 percent by weight is.”
Fuhrer said the grazing strategy paid off, not only in pounds produced at weaning but also in benefits to the soil composition.
“We started out with a pH of 5.8 and ended up with a pH of 6.8,” Fuhrer said. “Our hydrogen ion went from 6 down to zero and we took away the soil acidification issues.”
Changes in the environment come with changes in soil biology, and Fuhrer warned producers that when implementing any new strategy, there could be a period of correction where soil biology decreases.
“Sometimes we have to go down before we go up because the biology is going to correct itself,” Fuhrer said. “We can see the same thing in a cropping scheme, when cover crops are added and the biology has to adjust to that.”
While planting green increases soil productivity and soil biology, Fuhrer said adding grazing livestock takes the planting green strategy to a whole new level.
“The livestock always win the carbon contest,” Fuhrer said. “When you have more parts per million carbon, you’re going to have more soil biology because carbon is the food.”