Cover Cropping — Earth Innovations

Earth Innovations is a new series from Sound Agriculture that covers the up-and-coming techniques growers are deploying to keep their yields high and their land healthy for generations to come. In each blog post, we break down the benefits and challenges of incorporating new practices, using real growers’ experiences and the Sound Agronomy Team’s expertise.

Cover crops are often praised as one of the best practices to implement to create more sustainable and resilient operations and boost the soils’ microbiome health. But the benefits of introducing cover crops are sometimes obscure. In the first installment of our new Earth Innovations series, we’re exploring the benefits and challenges of cover cropping, as well as steps to consider before jumping in. 

Cover cropping is the practice of planting non-cash crops in order to keep live roots in the ground between seasons or periods of soil rest, which in turn helps to provide protection to the soil and store nutrients in the plant bodies. Growers then end the crop before it goes into the reproductive stage, sometimes before planting their cash crop. The most common method for terminating a cover crop is with herbicides or tillage it into the soil, but other methods, like mowing and crimping, are also effective. 

Cover crops can offer several benefits for growers, including nitrogen fixation, erosion reduction, water capture, and increased soil organic material. 

Boosting Nitrogen Availability and Retention

“One of the reasons people plant cover crops is to provide additional N to cash crops,” says Sarah Taylor, Sales Agronomist with Sound. ​“Some species can take nitrous oxide from the atmosphere and fix it using root nodules.” 

The root nodules on nitrogen-fixing plants house special bacteria that have formed a symbiotic relationship with these plants. Plants are very good at creating carbohydrates out of water and carbon dioxide through photosynthesis, but they may struggle to access other key nutrients like nitrogen and phosphorus. Certain bacteria can turn atmospheric nitrogen into plant-available forms right in the plant’s root, forming what are called root nodules. In exchange for the nitrogen stores these bacteria supply, the plant provides the bacteria with carbohydrates as a source of energy. 

When the crop is terminated before reproduction, roots and root nodules that are left in the ground will provide an in-season source of nitrogen to the cash crop and reduce the need to apply synthetic fertilizer. 

Erosion Control and Soil Protection

By keeping active roots in the soil all season long, cover crops can help reduce soil erosion and deterioration. Preventing soil loss is important because soil not only supplies organic matter and nutrients, it also holds water and provides habitat for beneficial microbes. 

“Having a cover crop in the ground can stop wind or water erosion from occurring because it prevents a lot of soil movement,” explains Sarah. The plants’ leaves and roots block wind and rain from picking up loose soil and carrying it offsite, robbing growers of nutrient-rich topsoil and potentially impacting nearby air quality or waterways. 

Soil loss is a global issue; the UN’s Food and Agriculture Organization estimates 33% of the Earth’s soils are already degraded and up to 90% could become degraded in the next 30 years. 

This loss has serious impacts for individual growers: degraded soils have reduced productivity, produce lower yields, and require increased water usage, all of which affects a grower’s bottom line. Cover crops are one way growers can protect and preserve their own nutrient-rich top soil. 

Improved Water Infiltration and Retention

Cover crops can have a big impact on a farm’s water quality and retention by helping to percolate and infiltrate rainwater. ​“When it rains,” says Sarah, ​“instead of the water just flooding off and moving away across the field, the water stays in the area where it fell, allowing it to settle into the soil.”

The vegetative canopy provided by a cover crop reduces the speed and intensity of raindrops on the soil. Without this protection, the force of rain on bare soil can break apart soil aggregates, which provide habitat for soil microbes and are responsible for healthy soil structure and adequate oxygenation. The crop’s roots also help the rainwater permeate deeper into the soil and prevent water loss through runoff. This allows growers to sequester rainfall for future use. 

Some growers may be worried that cover crops will increase their irrigation needs. While cover crops may need more water than fallow fields, those crops are actually holding moisture in the soil that will be available when the cash crop is planted. 

“It’s not wasted water to these plants — part of that is also preparing the bed for the cash crop,” says Sarah.

Building Organic Matter for Long-Term Soil Health

A soil’s organic matter (OM) content has a significant impact on its health, fertility, and nutrient availability. Soil organic matter is primarily made up of decomposing plant residue and animal wastes and can provide crops with a full spectrum of macro- and micro-nutrients, releasing them more slowly and with less risk of leaching. A high OM content also provides food for beneficial organisms in the soil and supports a robust soil microbiome. 

Building up OM in the soil can be a slow and difficult process, but cover cropping is one of the easiest strategies. Once the crop has been terminated, the plants are left in the soil to be decomposed and turned into nutrient-rich OM.

Natural Weed Suppression

Cover crops act as a natural defense system against weeds by forming a dense, fast-growing canopy that shades the soil surface. This canopy blocks sunlight from reaching weed seeds, disrupting their germination and early growth. As a result, fewer weeds emerge, reducing the need for herbicide applications and cultivation.

Beyond the immediate season, cover cropping can gradually reduce the soil’s weed seed bank. Fewer viable seeds in the soil leads to fewer problems over time, making weed management easier and more cost-effective with each passing year. A thick stand of cover crops means cleaner fields and less competition for your cash crop when it counts.

Pest and Disease Disruption

Introducing plant diversity through cover cropping helps break the repetitive cycles that pests and diseases thrive on. Instead of providing a continuous buffet for harmful insects and pathogens, a mixed-species cover crop interrupts their life cycles and limits their ability to spread.

Some species support beneficial insects that prey on crop-damaging pests, while others improve soil microbial balance to reduce disease pressure. By fostering a more biodiverse environment above and below ground, cover crops promote a healthier, more stable ecosystem — one that’s better equipped to resist outbreaks naturally.

Lower Input Costs Over Time

While cover cropping requires an initial investment, its long-term return often outweighs the cost. Healthier soil leads to better nutrient retention and water infiltration. Fewer weeds and pests reduce the need for herbicides and insecticides. Over time, these improvements allow growers to cut back on synthetic inputs while maintaining or even increasing yield.

Many growers start with small-scale cover crop trials to evaluate the benefits firsthand. Even limited use can result in noticeable improvements to soil structure and resilience. Over time, these gains translate into real economic value — with fewer inputs, more consistent yields, and greater confidence in the long-term health of the farm.

Not all cover crops serve the same purpose. Different species offer distinct advantages depending on a grower’s goals — whether it’s boosting soil fertility, suppressing weeds, improving structure, or supporting biodiversity. Understanding the main categories can help tailor a cover cropping strategy to fit specific needs.

Legumes

Known for their nitrogen-fixing abilities, legumes pull atmospheric nitrogen into the soil through root nodules, improving fertility for the next crop. They’re a smart choice for reducing synthetic nitrogen use and supporting soil health over time. Common options include clover, hairy vetch, and field peas.

Cereals

Fast-growing cereal grains like rye, oats, barley, and wheat are excellent for building organic matter, preventing erosion, and smothering weeds. Their fibrous root systems also help anchor soil and improve water retention.

Grasses

Grasses such as annual ryegrass and sudangrass provide similar benefits to cereals but are especially valued for enhancing soil structure and long-term weed control. Their fine roots create a dense underground network that holds soil in place and promotes microbial activity.

Brassicas

With deep taproots and strong scavenging abilities, brassicas like radishes, turnips, and mustards are ideal for breaking up compacted soil layers. They also help reduce nutrient loss and can contribute to pest suppression by disrupting pest life cycles and releasing natural biofumigants.

Other Cover Crops

Quick-growing species like buckwheat and sunflower offer rapid ground coverage, reducing erosion and weed pressure in short windows. Many also attract pollinators and beneficial insects, contributing to above-ground biodiversity and ecosystem health.

Mixing species from different categories can unlock even greater benefits. A thoughtfully blended cover crop mix can address multiple challenges at once — improving fertility, protecting soil, supporting beneficial organisms, and preparing the ground for a more successful cash crop season.

While the benefits of cover crops are well-documented, adopting them isn’t without hurdles. Successful implementation requires thoughtful planning, patience, and flexibility. Growers exploring cover cropping for the first time may encounter a few key challenges along the way.

Timing and Growing Season Constraints

Short growing windows, especially in cooler climates, can make it difficult to establish cover crops after harvest or before planting. Early frosts or late springs can further compress the season, reducing opportunities to get crops in the ground and established before winter.

Seed Costs and Financial Investment

Cover crop seeds and planting costs represent an up-front investment, which can feel risky — especially when margins are tight. However, many regions offer cost-share programs, conservation incentives, or technical assistance to help offset these expenses.

Management Complexity

Adding cover crops to a rotation introduces new management variables. Species selection, seeding rates, timing, termination methods, and integration with cash crops must all be carefully considered to avoid issues like nutrient tie-up or pest carryover. For many growers, it’s a learning curve that requires adjustment over time.

Weather Risks

As with any crop, cover crops are vulnerable to weather extremes. A dry fall may hinder germination, while a sudden frost can kill young plants before they establish. Weather challenges can also interfere with timely termination, potentially delaying cash crop planting.

Equipment and Labor Needs

Planting and terminating cover crops may require equipment modifications, additional passes across the field, or more hands on deck. For operations with limited labor or machinery, this can present logistical challenges, especially during already-busy seasons.

Delayed Return on Investment

Cover cropping is a long game. While improvements in soil structure, nutrient cycling, and water retention begin early, the most noticeable gains — like increased yield stability or reduced input needs — may take several seasons to appear. It’s a system that rewards consistency over time, not quick fixes.

Start Small, Stay Curious

The good news: growers don’t have to go all-in to see results. Starting with a small test plot can help build confidence and provide valuable field-specific insights. With expert guidance, trial-and-error, and a willingness to adapt, cover cropping can become a powerful tool in the long-term success of any farm system.

Kyle Mehmen has been cover cropping on his family’s Iowa farm since 2013 and he’s learned a lot about the practice in the last nine years. 

“Our journey really started out of necessity,” he says. The spring of 2013 was so wet that Kyle and his family had to stop planting without finishing. Faced with the prospect of bare soils until the next spring, they decided to try planting some cover crops. 

The results were good — those fields that rested a year with cover crops outperformed their historical yields the next year, he says. But like many growers, Kyle is pragmatic, and he’s hesitant to chalk it all up to cover crops. ​“They certainly didn’t hurt anything,” he says. ​“And we really liked what they did for us from a conservation standpoint.” 

When Kyle started cover cropping, the region had just come out of a few seasons of very rainy springs. ​“Wherever we had a cover crop, we were able to keep soil in place, and that was a huge benefit,” Kyle says. 

Timing and Seed Mixes: Making Cover Cropping Work in Iowa

Kyle is very conscious of the climate and location of his family’s farm — Iowa has a short growing season and early frosts, which has influenced not only their cover crop seed mixes, but also how and when they plant.

Some growers plant cover crops in the off season when the cash crop has been harvested and the fields are empty, but Kyle says they plant their cover crops into standing corn and soy around Labor Day. 

“We live far enough north that the idea of harvesting the existing crop and then planting the cover crops doesn’t work with our timing — we just run out of days before frost arrives,” he says. 

Some growers will plant cover crop seed mixes with as many as 10 species, but that just won’t work for Kyle, where most common cover crops will get wiped out by frost within six weeks of planting.

Understanding your farm’s strengths and limitations is key, and the local Natural Resources Conservation Service (NRCS) extension office is a good place to explore what might work for you. 

After years of experimentation, Kyle says his operation has settled on a system that allows them to feel comfortable increasing their cover cropping acreage each year. 

“We do cereal rye ahead of a field that will be planted with soybeans,” says Kyle. ​“We do oats ahead of a field that may be planted with corn so there’s no risk of extra competition for the corn coming up. That’s our base, but we still play with some broad leaves, vetch, and brassicas.” 

Sarah says it’s worth considering crop rotation and variation, even with cover crops. Rotating through crop families can help growers avoid pest pressures and soil diseases and even disrupt weed cycles. 

The Cost of Cover Cropping

Kyle cautions that successfully integrating cover crops takes time, and he encourages growers to think of it as a process

“Since we started learning about cover crops, we toyed with them for five or six years before we really started to scale the practice,” he says. ​“It’s a journey and it’s absolutely not linear.” 

For instance, last year, Kyle had terminated his cover crop and planted in his corn and soy in the spring as usual. ​“But on Memorial Day we had a killing frost, and anywhere that we had high residue or cover crops it froze the soybeans; all the beans were dead,” he says. ​“That’s what I mean when I say it isn’t linear — that was a pretty large setback.” 

But Kyle and his family did not decide to abandon cover crops. ​“Every year that you talk to me is going to be the biggest year that we’ve had in cover crops, because we just continue to scale. We’re not a 100% cover crop farm and I’m not sure if we ever will be, but every year we do a little bit more.” 

Even without unusual weather events, implementing cover crops does have costs. Sarah says some growers shy away from cover crops because of the input cost for seeds, but there are government-funded grants available to farmers that are specifically for cover crops. 

One of the biggest programs is the NRCS Environmental Quality Incentives Program (EQIP), which offers technical and financial assistance to growers interested in implementing a variety of conservation practices, including cover cropping. For growers already using some conservation practices, the Conservation Stewardship Program offers financial incentives and technical assistance for longer-term commitments to cover cropping. Because grant funding is county-specific, growers should contact their local NRCS agriculture extension office as a first step.

Kyle and his family have used EQIP grants throughout the years to help them keep learning and expanding their cover cropping.

“People will ask me if I think the cover crops are paying for themselves. Well, yes, I do think so — otherwise I wouldn’t keep doing it,” he laughs. ​“But I do continue to work with NRCS to keep getting funding to help me with this.” 

For many of the benefits Kyle has seen from cover cropping, it can be hard to assign a dollar value. 

“Any yield benefit or soil health benefit is a long-term play to me,” he says. ​“But we really like the physical things that we can see and can be hard to measure.” If there’s a particularly wet spring, they don’t lose soil anymore, he says, and in drier years, the cover crop roots help hold more moisture for longer. 

“We’re also finding that we are able to eliminate some chemistry early on, especially in our soybeans, because the rye is drowning out the weed competition,” he adds. ​“We really like that.”

While many factors are beyond a grower’s control, cover cropping offers a proven way to build on-farm resilience and reduce dependence on costly inputs. Though introducing cover crops can feel risky, the long-term benefits — including reduced soil erosion, improved nutrient availability, and healthier soil microbiomes — make it a smart investment in your farm’s future.

Kyle’s key advice for those new to cover cropping: start small and find what works best on your land. Every farm is unique, and beginning with manageable acreage can minimize financial risk while helping you develop effective practices and seed mixes.

Join growers like Kyle, who now cover over 6,000 acres with cover crops, building healthier soils and stronger yields year after year. Contact an agricultural expert today to learn more!