12. Kent Solberg, Crop Diversity & Soil

Kent Solberg is a livestock and grazing specialist for the Sustainable Farming Association, as well as a field consultant for Understanding Ag, and a farmer. He is interested in the ability of well-managed soil to transform farms, families, and even communities. He believes diversity is key.

“We’re focusing on these key principles of soil health: keeping the soil covered, minimizing disturbance, increasing plant diversity, keeping a living root in the soil, and integrating livestock,” said Solberg.

Many farmers interested in building better soil health on their farms are investing in keeping the soil covered and minimizing disturbance, but fewer are thinking critically about plant diversity and integrating livestock.

According to Solberg, including at least one of each of the three plant functional groups – grass, legume, and broadleaf – in a crop rotation can increase the health of the farm’s soil exponentially. In a typical corn/soybean rotation, farmers have a grass present in the corn crop and a legume present in the soybean crop, but adding a broadleaf can make a world of difference.

“Even if it’s not a crop we can harvest, we’re harvesting solar energy, we’re putting carbohydrates through photosynthesis into the ground, we’re freeing that microbial community, we’re keeping the soil covered – all of that building soil biology,” he said. 

Better soil biology builds soil aggregation, which increases the ability of the field to handle and hold water and impacts trafficability. Solberg admits that it is difficult to put a value on trafficability and being able to get into the field at the proper time, but that we all know intuitively how critical timing can be to farm productivity. With that in mind, trafficability is a tremendous factor worth considering. 

A lot of this is about being creative, says Solberg, and setting aside a few acres of your farm to try something new. Adding livestock could be a great way to bring a younger family member back to the farm, but if a livestock herd is not in the cards for you, he encourages thinking about custom grazing. A farmer can have the soil health benefit of adding livestock without the labor if he or she is creative about it.

“All the things we can control in the production and potential profitability of our farm fall under the ability to help that soil capture and store water and build that nutrient cycling,” said Solberg.

Learn how to implement additional crop and animal diversity to benefit your soil’s health in this podcast.

Utilizing Cover Crops as Forages

Harvest is approaching quickly and, with that, many people are thinking about getting cover crops seeded, if they haven’t already. As you plan for your cover crop, think about what your goals are. Do you plan on harvesting those cover crops for stored forages? Will you have livestock grazing the cover crop? Regardless of which you choose, these steps will help make sure your forage harvest is successful.

Cover crops for harvested forages

Harvested forages can be an added benefit from planting a cover crop. When planning for your cover crop, there are some things you should consider before sending the seeder to the field. While other crops can be used, the most commonly harvested cover crops for forages in the Midwest are cereal rye and the other cereal crops.

Cereal rye, wheat, triticale, and others can all make good forages for livestock. Make sure to review your seeding rate. Typically with a harvested forage, we will increase a rate by 50-100% to increase our final yields. For example, my typical cereal rye cover crop rate may be 45-60 pounds per acre. When planning to harvest that cereal rye for a forage, I recommend increasing that rate to 90-120 pounds rye per acre. This will help to increase total yield per acre when we go to harvest.

Also, consider adding fertilizer to the cover crop. Since we are now looking for an increase in biomass and will be taking a crop off, as well as stover, we will be removing those nutrients from the soil and not returning them. Talk to your SHP Field Manager or trusted agronomist to see what they recommend for a cover crop nutrition plan.

When it comes to harvest of the cover crop, timing is key. When and how you harvest will determine the nutritional value of the resulting forage. With cereal rye and other cereal crops, chopping or baling at the boot stage will ensure the best palatability and nutrition quality. As cereals get to the point of heading out, the lignin increases, which decreases forage quality and palatability for animals. Late-harvested cover crops are more ideally used as a low-quality forage part of a ration or bedding.

Cereal rye, in particular, can be difficult to dry down, so chopping is a good option. You can also make sure the stems are conditioned into small pieces, wind rows are wide, etc. to ensure conditions are ideal for drydown.

If you typically focus on planting early, harvesting forages from cover crops may cause a delay in those fields by a couple of weeks. For this reason, soybeans are a good option to follow harvested acres.

Grazing cover crops

Having livestock harvest the cover crops themselves is also an efficient way to add quality feed to your forage plan and to extend your grazing season. If you plan to graze the cover in the fall, one of the first things to look at is timing. Will there be enough time between seeding and when you intend to graze the cover crop for it to get off to a good start and produce a decent amount of biomass? 

One consideration may be seeding methods. Aerial seeding the acres intended for grazing may give the cover crop the longest time period for growth. If you would prefer to broadcast seed or drill following harvest, prioritizing those acres you plan to graze earlier in your harvest schedule will help to make sure you have more time to get seeding and potential growth. Looking forward to future years, plan ahead and plant an early corn hybrid or soybeans where you plan on grazing to give the cover the biggest growth advantage. Adding a winter-kill cover crop species – such as oats, radish, turnips, etc. – can add additional nutrition and biomass value to a grazing system.

Fence is a large consideration too. Does the field have any current fence and is it suitable for the livestock you plan to graze? In some cases, electric wire is enough to keep livestock in safely, but also consider what your state considers “lawful fence”. In Iowa, a fence for cattle must utilize 3-barbed wires or meet the other requirements defined by Iowa Code 359A.18.  If your cows get out and cause damage to crops or an accident, a single hotwire would not be adequate to meet those requirements. Make sure to double-check what is recommended in your state and by your insurance company.

Once your perimeter fence is adequate to keep your animals in, do you plan to continuous or rotational graze? Continuous grazing would be the simplest route. Rotational grazing would help your cattle to have a more uniform graze, which also allows for more consistent nutrition due to the reduction of selective grazing allowed.

Consider what species would be best for growth and grazing purposes. Check out our blog post comparing different types of cover crops. Talk to your local SHP Field Manager or agronomist to figure out what seed will fit your operation best. 

Based on where your farm is located, cover crop yields for grazing can be highly variable. Early seeding can help to improve yields, but early frost, late harvest and other factors can all play into the amount of biomass that the cover crop will provide for grazing purposes. It’s always good to have additional stored forages available.

Cover Crops and Nutrient Strategy in Iowa

Roger Zylstra and his son, Wesley Zylstra, on their Central Iowa farm

Business Case: Roger and Wesley Zylstra

Farmer Profile

  • Working with SHP since 2015
  • Experimenting with cover crops on their SHP research field
  • Total farmed area is 700 acres
  • Planting corn-soybean or corn-corn rotations
  • Using swine manure and spring/in-season nitrogen applications

Seven years ago, Roger and Wesley Zylstra set out to improve stewardship of their land. By paying attention to their nutrient management and incorporating cover crops, they started down the path of adapting their management system to meet soil health, yield and economic goals.


The Zylstras farm 700 acres in Central Iowa on primarily silt loam soils. They grow corn and soybeans, and their land is typically in a corn-soybean or corn-corn rotation. Roger and Wes also raise hogs on the farm, and swine manure provides an important source of nutrients for their cash crops.

When they started down the path of improving stewardship in 2014, the Zylstras were relying on fall-applied manure and anhydrous to meet the needs of the growing cash crop in the spring. They were interested in trying cover crops, but knew they would need to consider changing the source and timing of their nutrient applications if they were going to adapt their management system. Average farm-level corn yields in 2014 were around 170-190 bu/acre.

Crop management changes on the Zylstra farm

Cover crop trials began
  • The Zylstras used manure application and fall anhydrous until 2014.
  • On their own, they tested 12 acres of cover crops in 2014.
Cover crops on all soybean acres 
  • The Zylstras joined SHP to trial cover crops on one field in 2015.
  • They planted cover crops on all soybean acres using a broadcast spreader and incorporated cover crop seed with vertical tillage.


First year drilling cover crops
  • In 2016, they drilled cover crops to get better seed-to-soil contact and moisture availability.
  • The Zylstras timed nutrient application to meet cash crop needs with pre-plant and sidedress nitrogen (eliminated fall anhydrous).
Dialed in their system
  • The Zylstras adjusted cover crop seeding rates and methods in 2017.
  • During this season, they planted 70-90% of their acres to cover crops.
Determined best practices for their farm
  • In 2019, the Zylstras added liquid P and K to the planter & added zinc to their starter to further support yields.
  • They returned to broadcast-seeding cover crops and incorporating with vertical tillage, due to maintenance and time constraints.
Advanced soil health practices
  • In 2020, the Zylstras met their goal of eliminating dry fertilizer.
  • Due to weather, they attempted planting soybeans green into 2-foot-tall cereal rye with beneficial results (more on this below).

Choosing the right cover crop

In 2014, the Zylstras planted their first 12 acres of cover crops to cereal rye before soybeans.

To better measure the impact of cover crops on one of their fields, the Zylstras joined the Soil Health Partnership in 2015. They quickly transitioned to planting cover crops on all soybean acres in 2015. To start, they seeded cereal rye at 60 lbs/acre with a spreader and used a vertical tillage tool to incorporate the seed.

The Zylstras chose cereal rye because they were looking for a cover crop that withstood the disturbance caused by injecting manure; they found that cereal rye bounces back quickly in this situation and the stand was minimally affected. And, since cereal rye overwinters, it provides ground coverage and nutrient uptake throughout the fall and into the spring.

Roger Zylstra and son Wesley inspecting a no-till drill on their Central Iowa farm
Roger Zylstra and son Wesley inspecting a no-till drill on their Central Iowa farm

Adapting cover crop and nutrient management practices

Between 2016-2018, the Zylstras made a number of management changes in order to dial-in their system.

Eliminated use of fall anhydrous and incorporated spring pre-plant and sidedress applications.

These changes made nitrogen available to the corn plant in the spring – during the period of rye stover breakdown – and also timed nitrogen availability throughout the season for optimal cash crop uptake and minimal loss to the environment. Although injected nitrogen was their end goal, they used dry fertilizer spread on the soil surface during the transition.

Adjusted cover crop seeding rate.

In order to reduce the amount of biomass produced (and associated potential issues in establishing the next cash crop), as well as to lower overall cover crop seed cost, the Zylstras lowered seeding rates for cereal rye to 25-35 lbs/acre.

Experimented with different methods of seeding cover crops.

Beginning in 2016, Roger and Wes experimented with drilling their cover crop in order to get better seed-to-soil contact and to improve moisture availability. They liked the benefits of drilling; however, by 2019, they had decided to return to spreading and incorporating cover crop seed with vertical tillage. Using a spreader and vertical tillage, they lowered their equipment maintenance costs and were able to seed more acres in less time.

Advanced cover crop and nutrient management practices

Since 2019, Roger and Wes are taking even more steps to achieve their management goals – including experimenting with new cover crop management practices and advancing nutrient management on their operation.

100% liquid application of fertilizer.

In 2019, the Zylstras added liquid application equipment to the planter to allow for banded application of P and K on both sides of each planter row (1 in. over and 3 in. down), along with in-furrow, low-salt starter and extra liquid nitrogen (if no manure was applied).

Experimenting with “planting green”

The Zylstras typically terminate their cover crop early to minimize the chance of cover crops interfering with the establishment of the cash crop. This usually also allows them to plant sooner. However, in 2020, there was a field they were unable to spray on time, due to unfavorable weather conditions. As a result, they planted soybeans “green” – or directly into the still-growing cover crop. Roger felt they experienced slightly better weed control on that field, while also benefiting from more spring cover crop growth and more desirable timing in terms of when they could get in the field. With that in mind, the Zylstras are considering experimenting with planting green on more acres in the future.

“We use about the same amount of nitrogen per acre as we did many years ago, but our average [corn] yields have grown from 140-170 bu/acre to 170-200 bu/acre.” – Roger Zylstra


Respiration (in mg CO2/g dry weight) – an indicator of microbial activity – increased significantly on the cover cropped portion of the field, as noted in the chart above.

Add up the small changes and they bring real benefits

The Zylstras changed their management system by making incremental changes and experimenting over a number of years. What benefits do they see?

Same amount of nitrogen, higher yields.

The primary benefit that Roger and Wes see is the ability to improve nutrient use efficiency by changing sources and timing of application. While a liquid fertilizer program does cost more per unit, the nutrients are able to be used more efficiently by the crop. “In corn years, we allow the corn to utilize more of the nutrients,” Roger says. “And we are able to prevent nitrogen from leaching into our creeks and streams.”

Soil health testing suggests cover crops have increased microbial activity.

Results from soil health testing on the Zylstra’s Soil Health Partnership field show that respiration – an indicator of microbial activity – has increased significantly on the cover cropped portion of the field. One tangible benefit of this increased microbial activity at the farm scale has been an increased rate of residue turnover on acres with cover crops.

Improved soil structure.

The Zylstras credit improvements in soil structure with reducing soil surface compaction during the wet years of 2018 and 2019. In comparison to other farms in their area that created ruts in their field and had water standing after large rainfall events, they see fewer equipment tracks and less ponding. These improvements in soil structure also reduce the potential for erosion during times of maximum disturbance.

Mike Buis

Type of Operation:
Mike, with his brother Jeff, farms 3,100 acres. Most of the cropland is in a corn-soybean or corn-soybean-wheat rotation.

View on Soil Health:
Conservation Compliance provisions require Mike, who grow crops on highly erodible land (HEL), to use conservation practices to be eligible for federal programs such as disaster assistance, conservation programs, or crop insurance premium subsidies. Although he is not required to do so, he’s added cover crops to his HEL land to ensure he is going above and beyond to minimize soil erosion.

Reason for Joining Soil Health Partnership:
He began working with the Soil Health Partnership in 2016 to experiment with cover crops.

Trials Partnered with SHP on:
Mike broadcasts wheat cover crop seed at approximately 60 pounds per acre with a fall fertilizer application (immediately after harvest) and incorporates both with a vertical tillage tool. Wheat is not harvested, so he terminates the wheat cover crop in the spring when it is approximately 12-14″ tall by burning it down with an herbicide application. Because there is no spring tillage, he plants directly into the cover crop residue with a no-till planter.

His trial is featured in the Benefits of Cover Crops Business Case.

Other Soil Health Practices Being Implemented:

Mike has about 1/3 of his acres in no-till and 1/3 in minimal tillage. He also expanded the acres he plants cover crops beyond his SHP research field.

Advantages Experienced Using New Soil Health Practices:
The biggest benefit of the wheat cover crop, in Mike’s experience, is that he uses fewer herbicides during the growing season. He estimates the value of this weed control benefit to be worth at least $10/acre. Also, although he is not required to add cover crops to his HEL, doing so ensures he is going above and beyond to minimize soil erosion–and significant increases in soil organic matter on Mike’s research field between 2016 and 2018 suggest that Mike might see long-term benefits in soil water holding capacity and nutrient cycling and availability as a result of using cover crops.

Implementing cover crops on his HEL was a natural fit for Mike after he started experimenting with cover crops on his SHP research field. Because he had already adopted minimum-till on his HEL in order to meet conservation compliance requirements, there was no additional cost, other than the seed itself, to seed or terminate the cover crop. Putting a dollar value on weed control has encouraged Mike to increase the use of cover crops.

Roger Zylstra

The Zylstra farm is a third-generation family farm in Lynnville, Iowa. Roger’s parents began farming in 1948, and he purchased it from them in 1982. Now, Roger’s son, Wes, farms the ground and Roger works alongside him.  Together, they grow 700 acres corn and soybeans, as well as a contract finishing hog operation of 5400

The Zylstras have only recently added cover crops to their farming practice. The first year, they did a small field and put in cereal rye. It went very well, so the second year they did 300 acres of cereal rye. Roger says a cool, damp spring presented challenges, but the learning curve continues.

“We are dedicated to seeing this through,” Roger says. “I do think it will pay dividends in the long term.”

For 30 years, the Zylstras have practiced no-till on most all of their ground. Roger calls it the only practical way to farm their highly erodible land.

“I’m convinced we can improve the soil by doing cover crops, no-till and good nutrient management,” Zylstra said. “I’m looking forward to the research results and knowledge we will gain by participating with the partnership.”

Greg Whitmore

Greg raises corn, seed corn, corn silage and soybeans on about 2,600 acres, some of which he can trace back to his ancestor, a Civil War officer, and an 1879 homestead in Shelby, Nebraska.

Greg has deep roots with the Soil Health Partnership, joining at its inception in 2014. “I joined because I was using cover crops and no-till. I wanted to see if the economic and environmental gains and soil quality were real or just perceived,” said Greg. “Since joining, I have seen less wind and water erosion and better water infiltration and retention.”

Most of Greg’s cover crops follow the harvesting of silage for erosion control, and to help with nutrient retention of manure applications. Other cover crop acres follow seed acres, where he grows corn under contract with a seed company to produce seed corn for them. The cover crops help with weed control.

Greg practices no-till on most of the acres.

“I use strip-till ahead of the corn acres to place nitrogen, phosphorus and sulphur below where I will plant the seed,” Greg said. “On the manured acres, I can apply most of our nutrient needs with effluent from a large local dairy through our center pivots, which we must manage to meet state and federal guidelines.”

Greg says that a lot of little things can make the difference between success and failure. He’s had his cut of both, and wants to share that with other farmers to help them, and to learn from their experiences, as well.

Trinity Creek Ranch

Mikayla Tabert and her husband Benjamin are the third generation of Trinity Creek Ranch in Red Lake Falls, Minnesota, which her grandparents started in 1952. They farm alongside her parents, David & Peggy Miller. Together, they have a cow-calf operation that consists of 150 beef cows along with a small feedlot. Their diverse grain operation includes raising corn, soybeans, wheat, peola (field peas grown with canola), alfalfa, turfgrass, cereal rye and sunflowers. They also sell forage and cover crop seed.

The family enjoys experimenting with new practices and constantly challenges themselves to find ways to improve soil health and profitability. This often leads to fun internal competition about what they should try next with each family member having their own idea.

The family believes cover crops improve soil health and profitability, so they joined Soil Health Partnership for additional help collecting data to prove the practice and track changes in the soil. They would like to see fellow farmers adopt conservation practices, so they plan to use their data and experience to encourage others to consider utilizing cover crops.

Currently, they are considering testing 60-inch corn to increase interseeded cover crop growth and growing corn with interseeded cover crops for winter grazing that will not be harvested. They plan to continue to reduce the use of strip-till in order to become 100% no-till, expand their use of complex cover crops for grazing and to grow multiple crops together through polycrops and relay cropping.

Kevin Ross

For Kevin Ross, soil conservation is about more than helping the environment today – it is also a priority to ensure that his farm will stay productive long into the future. He hopes his young sons will continue his family’s long-term interest in agriculture and their Western Iowa operation. As an enrolled farmer in the Soil Health Partnership, Kevin takes part in measuring the economic and environmental outcome of his soil conservation practices, which he believes will help his farm stay productive and profitable for years to come. 

“We want to protect water, soil and air, and grow more with less. And, if we can make our business more profitable through sustainability – that’s a win for all of us,” he says.

Kevin is a sixth-generation family farmer from Minden, Iowa, where he and his family grow corn, soybeans and alfalfa, and operate a 140-head cow/calf operation.

Kevin grows corn almost exclusively using no-till methods. Over the past several years, he has also used different cover crops to prevent soil erosion, take up extra nitrogen and phosphorous in the field and provide forage for the cattle. 

“As with growing any new crop on the farm, cover crops have a learning curve, but the important thing is to get started, even if it is just a small area,” he says. “Cover crops are part of my long-term strategy for soil health because I recognize that visible changes will take time to understand and evaluate. We are hoping they come with profitable outcomes as well.”

Andrew Reuschel

Andrew and Jeff Reuschel of Reuschel Farms in Golden, Illinois grow primarily corn and soybeans on 1,200 acres, some of the same acres that have been in their family for five generations. The family first experimented with cover crops and no-till in the 1970s, then again in the early 1990s. Now, 20 years later, they are returning to cover crops and no-till practices across their farm.

Since 2016, Andrew has tried about 30 different cover crop species at various planting dates to reach specific goals. He is especially interested in growing cover crop “cocktails,” a mix of varieties that often includes buckwheat, cereal rye, clover, and radishes. The cocktail mix provides diversity that Andrew likes to see in his soil ecosystem.

The father-son team joined the Soil Health Partnership in 2017 to gain a better understanding of the effects of cover crops on their farms’ soil. Since using cover crops, they report much less soil erosion, but the Soil Health Partnership will help them understand the impact on their operation through scientifically collected data. The partnership also supports the Reuschels in learning best management practices and agronomic techniques specific for their farming goals.

“We’ve been here for five generations,” Andrew said. “We’re looking to have another five generations to be on this farm, and so we’re putting our soil first and yield second, and hopefully our soil will come back and repay us, as well as future generations.”