KNOWLEDGE IS POWER. A section of cover crops is clipped and sent to a lab for analysis. This helps the Imhoffs determine what nutrients should be available to the following crop.
WE MAY DRIVE red equipment, but green is our favorite color by far. A perfectly plowed field has nothing on the brilliant green mat dotted with hairy vetch flowers that dominates our tractor cab view when my cousin, Tim Imhoff, and I seed our crops.
As the mat turns brown and creates a protective shield, green crop seedlings, not weeds, poke through. Acres dedicated to multi-species cover crops make a green jungle for Tim’s cattle herd, and a green annual ryegrass cover crop mix splits corn rows as we look down from the harvester. Yeah, we really like green.
Green yields green, too. Since implementing cover crops in our long-term no-till fields, we have significantly increased the income derived from the same acres. Though it would seem we’re taking more from the soil by having it grow something constantly, instead we’ve seen soil health build and benefits compound.
My wife, Ginger, and I know we someday will turn over to Tim’s children, the seventh generation on this farm, a place that’s in far better condition to support them and their families.
CROPS: Corn, soybeans and winter wheat
It’s not that previous generations didn’t care for the soil. My grandfather and great uncle tried no-tilling in the early 1980s, but they lacked the tools and resources to make it work. They were twins and disagreed on the practice, so the struggle to make it work was twofold and the idea was eventually abandoned.
My father and I revisited the idea in the mid-1990s when we found ourselves shorthanded and disgusted with the severe erosion plaguing our rolling fields.
In 1993, we left land fallow after wheat harvest, intending to seed wheat again that fall. A weed flush prompted us to moldboard plow. That very night we got 9 inches of rain. Talk about sad shape. The field looked horrible with huge cuts. That was the last time a moldboard plow entered our fields and the last time we did any sort of deep tillage — chisels, plows, anything.
A decade made quite a difference for technology, chemistries, no-till equipment and knowledge. My father and I were able to easily adopt no-till when we tried. Dad bought a used Black Machine planter toolbar equipped with John Deere no-till planting units. It was configured to plant 12 30-inch rows, or the 3 outer rows on each side could be folded to make 6 15-inch rows.
Initially we used the planter to no-till Roundup Ready soybeans. With good success, we then dabbled with no-tilling corn, and before long we were 100% no-till. It cut labor considerably, and we weren’t compacting the soil as badly because we weren’t in the fields with a disc immediately in the spring trying to dry it down.
GREEN YIELDS GREEN. Cousins Tim and Mike Imhoff say implementing cover crops and adaptive multi-paddock grazing has helped them increase income without adding acres.
Ginger does all our spraying. Her job was critical in our early years of no-till but has dwindled significantly as we started using cover crops in the late 1990s.
Initially we were making a fall chemical application, a spring burndown and then another pass with a residual herbicide. It was a fight to keep fields free of waterhemp and marestail. The chemical bills were getting crazy.
Erosion was still a problem, too, despite no-till. We started planting a little cereal rye and wheat to try to curb erosion on any acres not growing a cash crop. We observed that fields that had grown those cover crops didn’t have winter annual weeds or the early flush of broadleaf weeds.
The double pull of reducing the chemical bill and countering erosion led us to experiment. We would drill or aerially broadcast some cereal rye in some corn fields ahead of soybeans. We ran light rates and focused on fields that had erosion or weed issues. Each year we planted more and more and had great luck no-tilling soybeans into the residue. We were a bit more unsure when it came to implementing the practice ahead of corn.
A good friend, Dave Kleinschmidt, had gotten into cover crops. After consulting with him, we seeded our first crimson clover crop in fall of 2014 for our 2015 corn crop. We spread it with the fall fertilizer application and harrowed it in. It made a fantastic crop of crimson clover, and I had never planted into soil as soft and perfect as I did that spring. Conditions were perfect, and I thought, “Man, this is easy!”
But something else happened, too. That fall I seeded crimson clover again. I had cereal rye aerially broadcast in an adjacent field. The plane overshot and there was a wide swath where both crimson clover and cereal rye were seeded together.
Where there was overlap, we were shocked to see there was 50% more biomass produced by the mix as there was where just clover was seeded. It’s like it was growing to compete with the cereal rye. After that we started seeding crimson clover and cereal rye together.
Since then, we’ve tried many mixes. I now use Balansa clover and black or Bob oats in place of cereal rye. We create 3-5-way mixes tailored to what we need for corn, soybeans or grazing. More on that later.
MAKE WAY. Cover crops are rolled with a cultipacker ahead of corn planting to keep the hairy vetch from wrapping. However soybeans can be drilled directly into the green cover crop with the John Deere airseeder.
I like a decent blend of legumes and grasses with a light rate of brassicas. We’ve found slugs love brassicas on our farm. That may not be true other places, but it’s been an issue here. That’s part of why we experiment, and others should, too.
Our typical blend ahead of corn would be Bob oats, hairy vetch, annual ryegrass, and kale or rapeseed. Our soils are very light. They don’t hold moisture well and tend to heat up quickly, resulting in even more lost moisture. To counter the effect, I prefer a heavier grass mix for my cover crops. Grass species provide a high volume of high-carbon residue that creates a lasting mat. The mat retains moisture and keeps the ground 12-15 degrees cooler in the summer.
Cool soil keeps soil microbes working to cycle nutrients for the growing crop. When soil temperatures creep into the high 90s, they start shutting down. We want to keep them at a happy 75 degrees F if possible.
DENSE ARMOR. Rolled cover crop mixes high in grasses and hairy vetch create a protective shield that blocks weeds and keeps soils significantly cooler.
The cover crop mix I’ve settled on ahead of corn consists of 30 pounds of Bob oats, 8 pounds of hairy vetch, 6 pounds of annual ryegrass, 10 pounds of barley and ½-1 pound of kale. Each of those plants interacts with the soil and the soil microbes in different ways. We want to give the microbes a buffet of options so they have everything they need to perform at their best.
Tim chases the combine all fall with the John Deere 1890 airseeder seeding cover crops. Every acre gets a cover crop every year. We want cover crops in the ground as soon as possible so they can take advantage of the warmth to get established and have a better chance of not freezing out.
The hairy vetch mix is rolled with a single gang cultipacker in the spring prior to planting corn. Laying it down keeps it from wrapping on the planter. The cultipacker doesn’t fully terminate the hairy vetch, and we’ve ordered a roller-crimper that we’re hoping will do a better job.
Corn is planted with a very simple “naked” 38-inch, 12-row twinline Kinze box planter. It can also be adjusted to seed 19-inch rows, which we might try in the future. There’s no pop-up fertilizer, coulters or row cleaners, just the double-disc openers. They cut right through the mat of biomass.
“Margins are so tight that you can’t shoot from the hip these days; you must measure…”
We did change out closing wheels. Running plain rubber closing wheels just squeezed the seed trench or didn’t close it at all due to the residue. Switching to notched Copperhead closing wheels gets through the residue to crumble the seed trench closed.
We used to run a center-fill planter, but we could see where the weight was compacting the soil in the middle so we switched back to a box drill. Individual boxes also allow us to experiment.
We’ve found not all corn hybrids or soybean varieties work well with covers.
Each year we take the hybrid or variety that worked best the past year in a certain field or situation and put it in half the planter. Then, our agronomist recommends what he thinks might work best and we put that in the other half. At year-end, we see which one worked better and select it for the following year to be put against a new hybrid/variety. Plant breeding moves so fast, I imagine we’ll always use this split system to keep us planting the best seed for our acres and system.
Cover crops allowed us to work with Tim so he could run cattle on the farm. He has a small herd of cows and fattens calves. This has added a completely new revenue stream to the place but has required some shifts to the system.
We switched from 20-inch corn to 38-inch rows, for one. Tim needs to be able to graze cover crops as soon as possible in the fall. With the wider rows, we’re able to go in with a twin-row Great Plains drill when corn is at V5-V7 and seed covers between the corn rows. This is only done on fields Tim will graze.
BEEFING UP. Grazing cover crops increases farm revenue and serves to improve soil health. Cattle are grazed in paddocks and moved daily. Plenty of residue is left to protect the soil and feed soil microbes and manure and urine are spread evenly across the field.
Wider rows allow for more air movement and light for the growing cover crops. The mix includes annual ryegrass, turnips, radishes, clovers and hairy vetch. We’re able to plant them early because those species will come up and get started, but when it gets hot, they go dormant until the canopy opens in the fall and the temperatures cool off. Then it takes off again.
To make sure Tim always has grazing, we also plant a few fields to whatever multi-species grazing mix he decides on in the spring. Those fields are then grazed in summer and planted to whatever fall mix we want for the crop we’ll plant next spring.
He uses the adaptive multi-paddock (AMP) grazing system. There’s a perimeter fence around the fields, and he stretches polywire across the field to make temporary paddocks. Cows move to a fresh paddock daily. Forage is monitored closely so only half is taken and the rest trampled.
Constant movement helps spread manure and urine evenly across the field as there’s no one spot where the cattle linger. The water and mineral moves with them every day. It really helps the soil biology.
If it gets muddy, cattle are pulled from the field so it doesn’t get torn up, though the residue mat makes that a pretty low risk.
After harvest, cattle are moved to harvested corn fields where cover crops are already growing. We’re 3 years into the livestock business, and we’re not to scale yet. However, the goal is to get Tim farming full time without adding acres, and we’re making progress in that regard.
Measurement is an important part of our system. You can’t know you’re headed in the right direction and how far you’ve come if you don’t evaluate the system along the way. Margins are so tight that you can’t shoot from the hip these days; you must measure.
Soil samples taken 5 years apart proved we’re headed in the right direction. Our average — not top — soil organic matter on the farm increased 1% during that time.
DOUBLE DUTY. Corn acres not previously seeded for grazing get a cover crop mix drilled in immediately after harvest.
There are also annual assessments. Close to planting in April, we cut biomass samples from a 3-by-3-foot area. They’re shipped to Regen Ag Labs in Nebraska. They deliver an in-depth analysis of nutrients in the residue: nitrogen (N), phosphorus (P), potassium (K), calcium, sulfur and more. That information helps us know how much we can expect for the cash crop and what we will have to add with commercial fertilizer.
I inject 32% N on a diagonal to where I’ll plant corn prior to rolling the hairy vetch cover crop in the spring. Though our yield goals say we should be applying 180-200 pounds of N, we only put down about 125 pounds of N. We’ve cut our rate back quite a bit due to N-fixing cover crops and active soils.
Not all nutrients are available immediately and not all nutrients will be available the first year. This is especially true with the high-carbon grass cover crops I plant for soil armor that are, as I wanted, slow to breakdown. Depending on the species mix, I will allow for a certain percent of nutrients and make up the difference.
Though my overall fertilizer rate is reduced due to what I know to expect from the cover crops, I always overshoot the applied rate a bit as I don’t want the crop to want for anything. I know the next cover crop will be there to take up any nutrients that don’t get used.
The benefits are piling up. Grazing cover crops has revenue on the rise. Equipment has been downsized or eliminated. We no longer need the big 4WD tractors, now it’s all front assists that are lighter, can do more and require less maintenance. Our only tools are the planter, drill, airseeder, roller-crimper and sprayer.
Soil tests show soil organic matter is increasing, all while we’re producing more than ever. Cover crops are stopping erosion, providing armor for the soil and allowing us to cut back on fertility.
Our light soils compact easily, but cover crops are clearing old compaction layers. There used to be a compaction layer at 9 inches, but we’ve busted through it. Now cover crop roots are working on the layer at 13 inches.
When we dig in the spring, soils that used to be yellow are turning chocolate in color. We now have a 6-inch layer of rich, brown, mellow, highly productive topsoil. At harvest this fall, I was able to poke my finger into the soil past the first knuckle. That wouldn’t have been possible even with just no-till.
Since 2011, Martha has authored the highly popular “What I’ve Learned About No-Till” series that has appeared in every issue of No-Till Farmer since August of 2002.
Growing up on a cattle ranch in southeastern Montana, Martha is a talented ag writer and photographer who lives with her family in Billings, Montana.
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