Cover Crop
Demonstration Plot
16049-16507 NE 42nd St. Cambridge, IA 50046
Playlist
1:19
2:28
About the Plot
This Cover Crop Demonstration Plot was designed by the Polk Soil and Water Conservation District. Its goal is to provide a visual, side-by-side comparison of various cover crop species that are frequently planted in Central Iowa.
The five acre plot is divided into eight fields seeded with different cover crop mixes. The species rotate with each season planting. As of August 27 for our Fall 2024 planting, the plot demonstrates Rye, Triticale, Oats, Mustard, Radish, Turnip, Rapeseed, Winter Wheat, Vetch, and Camelina.
The plot is open full time for self guided tours. Field maps and guides are provided on site and are also available on site by QR code.
Cover Crop Demonstration Plot Field Guide
The Cover Crop Demonstration Plot has been planted to provide farmers and landowners a way to compare both Cover Crop species and mixes that are valuable to grow in Central Iowa.
All Covers Crops were planted on August 27th 2024 using a seed drill following minimal tillage. The five-acre plot had been planted in 2023 with only cover crops in the Fall of 2023. These included Vetch, Rye, Radish, Oats, Camelina, and Turnips. Two of the five acres had also been planted to sweet corn during the early summer of 2024.
Included is an explanation of the cover crops that have been planted in 2024. Refer to the Field Numbers along with an explanation of the crops that have been planted.
Field 1 – Multi – Species Mix - Cereal Rye, Vetch, Radish, and Camelina
Rye – Seeding Rate – 22.5 lbs/acre – Cost – $.25/lb
Hairy Vetch – Seeding rate – 6 lbs./acre – Cost $2.75/lb
Radish – Seeding Rate – 2.5 lbs/acre – Cost $1.50/lb
Camelina – Seeding Rate – 1.5 lbs/acre – Cost $2.75/lb
Using a combination of Cereal (winter) Rye, Hairy Vetch, Radish, and Camelina as a cover crop in central Iowa creates a synergistic effect that can address various agronomic and environmental concerns while promoting soil health. Here are the specific benefits of each component and the combination as a whole:
1. Cereal Rye
• Cold Tolerance: Rye is one of the hardiest cover crops and can establish in cooler temperatures, making it effective for fall planting in central Iowa.
• Erosion Control: Rye provides excellent ground cover, reducing soil erosion by protecting the soil from wind and water.
• Nutrient Scavenging: It scavenges excess nitrogen and other nutrients from the soil, preventing them from leaching into waterways, which helps improve water quality in Iowa.
• Weed Suppression: Its fast growth and dense canopy help suppress weed competition, reducing the need for herbicides.
2. Hairy Vetch
• Nitrogen Fixation: As a legume, hairy vetch can fix atmospheric nitrogen into the soil, enriching the nitrogen content for the following crops.
• Soil Structure Improvement: Vetch has a deep root system that improves soil tilth, structure, and organic matter content.
• Extended Nitrogen Release: It releases nitrogen slowly as it decomposes, ensuring a more extended release for future crops, which is beneficial for nutrient management.
3. Radish (Daikon or Tillage Radish)
• Compaction Alleviation: Radish roots are known for their ability to break up compacted soil layers, creating channels that improve water infiltration and root penetration for subsequent crops.
• Nutrient Scavenging: Radishes can also capture and store nitrogen and other nutrients, reducing nutrient losses during the winter.
• Organic Matter Addition: As radishes decompose, they add organic matter to the soil, promoting soil microbial activity and nutrient cycling.
4. Camelina
• Drought Tolerance: Camelina is a drought-tolerant crop that can help manage soil moisture, especially in years with irregular rainfall, common in central Iowa.
• Pollinator Support: Camelina flowers early in the growing season, providing habitat and nectar for pollinators and beneficial insects.
• Soil Health: Its fibrous root system improves soil texture and helps maintain soil fertility by contributing to organic matter.
Benefits of the Combination:
1. Enhanced Nutrient Management:
• Nitrogen Fixation and Cycling: Vetch fixes nitrogen, while rye and radish capture and recycle nutrients, creating an efficient system for maintaining soil fertility. This reduces nitrogen leaching into groundwater and nearby water bodies, which is vital for water quality improvement initiatives in Iowa.
2. Improved Soil Structure and Water Infiltration:
• Radishes alleviate soil compaction, improving water infiltration, while rye and vetch build organic matter, which enhances soil tilth and moisture-holding capacity. This benefits fields prone to heavy rainfall or dry spells, both of which are common in central Iowa.
3. Erosion Control and Weed Suppression:
• The dense cover provided by rye and vetch minimizes soil erosion during the fall, winter, and early spring. Rye and radish suppress weeds effectively, reducing reliance on herbicides. 4. Enhanced Biodiversity:
• A diverse cover crop mix promotes a healthy soil microbiome by supporting different types of soil organisms. This biodiversity enhances soil health and resilience against pests and diseases, fostering more sustainable farming practices.
5. Moisture Management:
• The combination of deep-rooting crops like radish and moisture-efficient crops like Camelina ensures better moisture retention and drainage in the soil. This reduces the risk of waterlogging and helps conserve water during dry periods.
6. Economic Benefits:
• By reducing the need for chemical fertilizers (through nitrogen fixation and nutrient scavenging) and herbicides (via weed suppression), this cover crop mix can lower input costs. Improved soil health and water management also contribute to long-term farm productivity.
Summary: A combination of rye, vetch, radish, and Camelina offers a broad range of benefits for central Iowa farmers. These include improved soil health, better nutrient management, erosion control, weed suppression, and support for beneficial insects. By integrating this cover crop mix into their rotation, farmers can reduce input costs and promote long-term productivity while improving environmental outcomes.
Field 2 – Single Species - Triticale
Seeding Rate – 45 lbs/acre – Cost – $.45/lb
Triticale, a hybrid of wheat and rye, offers several benefits as a cover crop in central Iowa, particularly for soil health, water quality, and overall farm management:
1. Erosion Control: Triticale provides dense ground cover, especially during fall and winter, protecting the soil from erosion due to wind and water, which is crucial during Iowa’s wetter seasons.
2. Nutrient Scavenging: Like wheat and rye, triticale is effective at scavenging excess nitrogen and other nutrients left in the soil after the main crop’s harvest. This helps reduce nutrient leaching into waterways, improving water quality.
3. Soil Health Improvement: Triticale contributes organic matter to the soil when it is terminated, helping to build soil structure, improve water infiltration, and increase soil microbial activity, promoting long-term soil fertility.
4. Weed Suppression: Triticale establishes quickly, providing a thick cover that suppresses weeds by outcompeting them for light and nutrients, reducing the need for herbicides in the spring.
5. Cold Tolerance: Triticale is highly cold-tolerant, making it suitable for planting in the fall and maintaining ground cover through the harsh central Iowa winters.
6. Flexibility in Crop Rotation: Triticale can fit well into rotations with other crops like corn and soybeans. It can be grazed, harvested as forage, or terminated to plant the next cash crop, offering flexibility depending on the farm’s needs.
7. Dual-Purpose Use: Triticale can be used both as a cover crop and a forage crop, providing an additional economic benefit for livestock farmers. It can be grazed in the spring or harvested for silage or haylage.
8. Water Retention and Infiltration: Triticale’s root system improves soil structure, which helps retain moisture in the soil, enhancing drought resistance and water use efficiency for the subsequent crop.
These benefits make triticale a versatile and beneficial cover crop for central Iowa farmers, especially those looking to improve soil health, prevent nutrient loss, and enhance farm profitability.
Field 3 – Single Species - Cereal Rye
Seeding Rate – 45 lbs/acre – Cost – $.25/lb
Using rye, particularly cereal rye, as a cover crop in central Iowa provides numerous benefits that can enhance soil health, water quality, and farm management practices. Here are the key advantages of incorporating rye as a cover crop:
1. Erosion Control – Year-Round Soil Cover: Rye grows quickly and establishes dense ground cover in the fall, protecting the soil from erosion caused by wind and water throughout the winter and early spring. This is especially important in central Iowa, where erosion risks are high during periods without crops.
2. Nutrient Scavenging – Nitrogen Uptake: Rye is highly effective at scavenging excess nitrogen left in the soil after the cash crop harvest. This prevents nitrogen from leaching into waterways, improving water quality and reducing nutrient loss. Nutrient Cycling – Rye holds onto these nutrients through the winter and releases them back into the soil when it decomposes, making them available to the next crop.
3. Weed Suppression – Allelopathic Properties: Rye releases allelopathic compounds that can inhibit the germination of weed seeds, providing natural weed control without herbicides. This reduces competition from weeds in the spring, benefiting the subsequent crop. Dense Canopy – The thick growth of rye also shades the soil, reducing weed emergence by outcompeting them for sunlight and nutrients.
4. Improvement of Soil Health – Organic Matter Addition: Rye adds significant amounts of biomass to the soil when it is terminated, improving soil organic matter levels. This helps to build soil structure, improve water infiltration, and increase soil microbial activity, which is important for nutrient cycling and maintaining healthy soil ecosystems.
5. Soil Compaction Reduction – Deep Root System: Rye has a deep and fibrous root system that can help break up compacted soil layers. This improves soil structure, increases water infiltration, and reduces surface runoff, which is especially useful in fields prone to compaction.
6. Cold Tolerance and Flexibility – Winter Hardiness: Rye is highly cold-tolerant and can survive Iowa’s harsh winters, providing continuous soil cover even in extreme conditions. It resumes growth in early spring, offering early-season benefits before the cash crop is planted. Flexible Termination: Rye can be terminated at various stages in the spring, depending on the farmer’s goals. Whether using herbicide, tillage, or mowing, it offers flexibility in management.
7. Improved Water Management – Enhanced Infiltration: By improving soil structure and reducing compaction, rye helps increase water infiltration and reduce surface runoff. This leads to better water retention in the soil, which benefits the next crop, especially during dry periods.
8. Integration with Crop Rotations – While Rye is compatible with Corn and Soybean Rotations, it is commonly used prior to planting soybean the following Spring in Iowa.
Summary of Rye Benefits:
• Erosion Control: Rye prevents soil loss during fall, winter, and early spring.
• Nutrient Scavenging: Reduces nitrogen leaching and recycles nutrients.
• Weed Suppression: Allelopathic properties and dense growth inhibit weeds.
• Soil Health Improvement: Increases organic matter, improves water infiltration, and promotes microbial activity.
• Water Quality Protection: Reduces nutrient runoff and sediment loss.
• Cold Tolerance: Survives Iowa winters, offering flexibility in crop management.
• Carbon Sequestration: Contributes to climate change mitigation by capturing carbon in the soil.
In conclusion, rye is an excellent choice for farmers in central Iowa seeking to improve soil health, prevent erosion, enhance nutrient cycling, and reduce weed pressure, all while protecting water quality.
Field 4 – Multi-Species mix - Oats and Mustard
Seeding Rate – Oats 30 lbs/acre – Cost – $.35/lb
Mustard 1.5 lbs/acre – Cost – $3.00/lb
Using both oats and mustard as a cover crop combination in central Iowa offers a range of complementary benefits that can enhance soil health, nutrient management, and overall farm productivity. Here are the key benefits of this combination:
1. Oats –
• Erosion Control: Oats establish quickly in the fall, providing a dense cover that protects the soil from erosion caused by wind and water, particularly during the fall and winter months.
• Nutrient Scavenging: Oats absorb excess nutrients, especially nitrogen, from the soil, helping to reduce nutrient leaching into waterways. This improves water quality and preserves nutrients for future crops.
• Soil Organic Matter: When oats die off (often due to winter kill in central Iowa), their biomass adds organic matter to the soil. This improves soil structure, enhances water infiltration, and promotes microbial activity.
• Easy Termination: Oats typically winterkill in Iowa, making them easy to manage in the spring. This reduces the need for mechanical or chemical termination, simplifying the process for planting the next crop.
• Weed Suppression: The quick growth and dense canopy of oats help suppress weeds by outcompeting them for light and nutrients during the fall, reducing the need for herbicides in the following season.
2. Mustard
• Biofumigation: Mustard contains compounds called glucosinolates, which break down into natural biofumigants (isothiocyanates) that can help suppress soil-borne pests, pathogens, and certain weeds. This can reduce the reliance on chemical pesticides.
• Nutrient Scavenging: Mustard is effective at scavenging nutrients, particularly nitrogen, from the soil. It captures excess nitrogen and other nutrients that would otherwise be lost to leaching, making them available to the next crop.
• Soil Health and Organic Matter: Like oats, mustard adds organic matter to the soil when it decomposes. This improves soil structure, increases water retention, and promotes beneficial microbial activity.
• Weed Suppression: Mustard grows quickly and densely, shading out weeds and reducing their establishment. Its allelopathic properties can also inhibit weed seed germination, providing natural weed control.
Combined Benefits of Oats and Mustard
1. Complementary Growth Timing: Oats and mustard both establish quickly in the fall, but oats are more likely to winter-kill, while mustard can survive longer depending on the winter severity. This combination provides continuous soil cover into late fall and possibly early winter, protecting soil and reducing erosion.
2. Enhanced Soil Health: Oats contribute substantial biomass that decomposes easily, while mustard’s deeper taproot can help break up compacted soil layers, improving soil structure and root penetration for future crops.
3. Nutrient Cycling and Scavenging: Both crops are excellent at capturing and recycling nutrients, particularly nitrogen. This prevents nutrient leaching during winter and ensures that nutrients are retained in the soil for the spring planting season.
4. Improved Water Quality: By reducing erosion and nutrient leaching, the oats and mustard combination helps protect water quality in Iowa’s watersheds, contributing to nutrient management goals and water quality improvement efforts.
5. Weed and Pest Suppression: The rapid growth and dense canopy of both crops help suppress weeds by reducing light and space for them to grow. Mustard’s biofumigation properties further enhance pest and disease suppression, making this mix an effective tool for integrated pest management (IPM).
6. Low Maintenance: Oats often winter-kill in central Iowa, making them easier to manage in the spring. Mustard can be terminated with light tillage or mowing if it survives the winter, offering flexibility in managing the cover crop without the need for chemical termination.
Overall, the oats and mustard cover crop mix provides a powerful combination of soil protection, nutrient management, weed suppression, and pest control. This blend is well-suited for central Iowa’s climate and agricultural systems, offering benefits for both short-term farm management and long-term soil health.
Field 5 – Multi-Species Mix - Radish, Turnip, Rapeseed and Oats
Seeding Rate – Radish 2.5 lbs/acre – Cost – $1.50/lb, Turnip 1.5 lbs/acre – Cost -$1.80/lb, Rapeseed 1.5 lbs/acre – Cost -$1.50/lb, Oats 30 lbs/acre – Cost – $0.35/lb
Using a mix of radishes, turnips, rapeseed (canola), and oats as a cover crop in central Iowa offers a range of benefits that contribute to soil health, water quality, and overall farm productivity. Here’s a breakdown of the specific advantages of this combination:
1. Radishes (e.g., Daikon or Tillage Radish)
• Soil Compaction Reduction: Radishes develop deep taproots that can penetrate compacted soil layers, creating natural channels for water and air infiltration. This improves soil structure and can alleviate hardpan layers in the field.
• Nutrient Scavenging: Radishes are excellent at capturing excess nitrogen and other nutrients from the soil, reducing the risk of nutrient leaching during the offseason and making those nutrients available for the next crop.
• Soil Aeration: When radishes decompose, they leave behind holes in the soil that improve aeration and water movement, which benefits root growth for future crops.
2. Turnips
• Additional Organic Matter: Turnips, like radishes, grow large roots that decompose after they are terminated, contributing organic matter to the soil. This enhances soil fertility and improves soil water-holding capacity.
• Nutrient Recycling: Turnips can absorb nutrients from deeper in the soil profile and release them back to the surface as the crop decomposes, making them available for subsequent crops.
• Forage Potential: Turnips can also be used as a forage crop for livestock, providing a dual benefit for farmers who graze animals.
3. Rapeseed (Canola)
• Nitrogen Fixation and Scavenging: As a member of the Brassica family, rapeseed helps scavenge residual nitrogen from the soil, reducing nutrient runoff. It can also take up other nutrients, preventing them from leaching out of the soil profile.
• Weed Suppression: Rapeseed grows densely and quickly, which helps outcompete and suppress weeds during the fall and early winter, reducing the need for herbicides in the next growing season.
• Improved Soil Health: Rapeseed adds organic matter to the soil when terminated, improving soil structure and promoting microbial activity, which enhances soil health.
4. Oats
• Soil Erosion Control: Oats establish quickly in the fall, providing excellent soil cover that protects against erosion caused by wind and water.
• Nutrient Uptake: Oats absorb excess nutrients, particularly nitrogen, helping to prevent leaching and improving nutrient availability for the following cash crop.
• Winter-Kill Benefit: In central Iowa, oats generally winter-kill, which makes them easy to manage in the spring as they decompose, providing organic matter without the need for termination measures.
Combined Benefits of the Mix
• Soil Health Improvement: Together, this mix of cover crops improves soil structure by breaking up compaction, adding organic matter, and increasing water infiltration. This enhances soil tilth and supports microbial life, which is crucial for long-term soil fertility.
• Nutrient Management: The combination of radishes, turnips, rapeseed, and oats helps capture and recycle nutrients, particularly nitrogen, reducing nutrient loss through leaching and improving nutrient availability for the following crops.
• Weed and Pest Suppression: The fast-growing nature of oats and rapeseed, combined with the dense root systems of radishes and turnips, helps suppress weeds and can even reduce pest populations by disrupting their life cycles.
• Water Quality Improvement: By reducing erosion and preventing nutrient runoff, this mix of cover crops helps protect water quality in local watersheds, which is particularly important for addressing nutrient pollution issues in central Iowa.
• Forage Option: Turnips and rapeseed offer grazing opportunities for livestock, providing an additional economic benefit to livestock farmers.
This combination of radishes, turnips, rapeseed, and oats provides a multi-functional cover crop that not only improves soil health and nutrient cycling but also offers benefits like weed suppression, forage potential, and enhanced water quality. It’s particularly well-suited for central Iowa’s climate and farming systems.
Field 6 – Single Species - Winter Wheat
Seeding Rate – 45 lbs/acre – Cost – $0.29/lb
Using winter wheat as a cover crop in central Iowa provides a variety of benefits, particularly for soil health, water quality, and farm management:
1. Erosion Control: Winter wheat establishes well in the fall, covering the soil during the vulnerable winter months, reducing soil erosion caused by wind and water, especially after the main crop has been harvested.
2. Nutrient Scavenging: Winter wheat helps absorb excess nutrients, especially nitrogen, left in the soil after the growing season. This prevents nutrient runoff into streams and rivers, improving water quality and reducing the risk of nitrate pollution.
3. Soil Health Improvement: When winter wheat is terminated, it adds organic matter to the soil, enhancing soil structure, promoting better water infiltration, and increasing microbial activity. This contributes to long-term soil health and resilience.
4. Weed Suppression: Winter wheat grows densely, providing strong competition against weeds by shading the soil and using available resources, which reduces the need for herbicides in the following crop season.
5. Cold Hardiness: Winter wheat is highly cold-tolerant, making it a reliable cover crop for central Iowa’s harsh winters. It continues to grow in the early spring, providing extended cover and protection until the main crop is planted.
6. Water Retention: By improving soil organic matter, winter wheat helps retain soil moisture, which can be beneficial for the next growing season by making crops more drought-resistant and improving water use efficiency.
7. Flexible Crop Rotation: Winter wheat fits well into various crop rotations. It can be grazed, harvested as forage, or terminated to plant the next cash crop, offering flexibility depending on the farm’s needs.
By using winter wheat as a cover crop, farmers in central Iowa can protect their soil, reduce nutrient loss, improve water quality, and enhance their overall farming sustainability.
Field 7 – Single Species - Hairy Vetch
Seeding Rate – 12 lbs/acre – Cost – $2.75/lb
Hairy vetch is a leguminous cover crop that provides several key benefits for farmers in central Iowa, especially when it comes to improving soil health, water quality, and overall farm sustainability:
1. Nitrogen Fixation: As a legume, hairy vetch can fix atmospheric nitrogen into a form available to plants. This reduces the need for synthetic nitrogen fertilizers in the following crop, benefiting crops like corn that require high nitrogen levels.
2. Improved Soil Health: Hairy vetch adds organic matter to the soil when terminated, improving soil structure, increasing water infiltration, and promoting microbial activity. This organic matter helps build long-term soil fertility.
3. Erosion Control: Hairy vetch provides good ground cover during the winter and spring, protecting the soil from wind and water erosion, especially on sloped or erosion-prone fields.
4. Weed Suppression: Its dense growth habit helps suppress weed growth by shading out weed seedlings, reducing the need for herbicides.
5. Water Retention: By improving soil structure and organic matter, hairy vetch can help retain moisture in the soil, making fields more drought-resistant and improving water use efficiency.
6. Flexibility in Rotation: Hairy vetch works well in rotations with corn, soybeans, and other crops. It can be terminated in the spring, allowing for timely planting of the main cash crop.
7. Cold Tolerance: Hairy vetch is relatively cold-tolerant, making it suitable for central Iowa’s winters. It establishes well in the fall and resumes growth in the spring.
These benefits make hairy vetch a strong choice for cover cropping in central Iowa, particularly for farmers interested in improving soil health, reducing input costs, and enhancing sustainability on their farms.
Field 8 – Single Species - Oats
Seeding Rate – 60 lbs/acre – Cost – $0.35/lb
Using oats as a cover crop in central Iowa offers several benefits, particularly in relation to soil health, water quality, and farm management practices. Here are some key advantages:
1. Soil Erosion Control – Oats establish quickly, providing good ground cover, which helps reduce soil erosion from wind and water. This is particularly important on sloped or exposed soils common in parts of central Iowa.
2. Weed Suppression – Oats can outcompete many weed species by shading them out, reducing the need for herbicides. As they grow rapidly, they form a thick canopy that limits weed germination and growth.
3. Improvement of Soil Structure – The root system of oats helps improve soil structure by enhancing soil aeration and promoting water infiltration. The fibrous roots contribute to building soil organic matter when the crop breaks down.
4. Nutrient Scavenging – Oats can capture leftover nitrogen from the previous crop, reducing nutrient leaching into water systems. This is beneficial for nutrient management and for improving water quality in central Iowa watersheds.
5. Organic Matter Addition – When terminated or allowed to decompose, oats add organic matter to the soil, boosting microbial activity and improving overall soil health.
6. Moisture Management – Oats use water efficiently, reducing moisture loss in the soil profile, especially in the spring. They also help to prevent the soil from drying out and can be valuable for managing water in fields prone to either excess moisture or drought conditions.
7. Ease of Establishment and Termination – Oats are relatively easy to establish, even in cooler conditions in the early spring or late summer. They also winter-kill in Iowa, meaning they typically die off in the colder months, which reduces the need for mechanical termination in the spring.
8. Economic Benefits – Oats are cost-effective compared to other cover crops like rye or clover. They offer a lower-cost option for farmers looking to implement cover crops into their rotations, with minimal additional management requirements.
In the context of central Iowa’s farming systems, oats as a cover crop can help farmers improve soil health, reduce input costs, and address conservation goals like reducing nutrient runoff and improving water quality—important priorities in the state’s Water Quality Initiative (WQI) programs.
2023 Map
This Cover Crop Demonstration Plot was designed by the Polk County Soil and Water Conservation District. Its goal is to provide a visual, side-by-side comparison of various cover crop species that are frequently planted in Central Iowa.
The Demonstration Plot consists of five, one-acre plots. Each plot has a different cover crop (or mix) growing in it.
There is Cereal Rye, Oats, Camelina, a Turnip and Radish mixture and a ‘Summer Grazing Blend’ that contains a mix of pearl millet, oats, cowpeas, turnip, rapeseed, sorghum-sudan, buckwheat, and crimson clover. There was also a “bonus” species – hairy vetch, that was planted last Fall and did not get terminated well with just glyphosate.
View Polk SWCD’s 2023 Cover Crop Insights.
The goal of Polk SWCD is to protect water quality and conserve natural resources in Iowa.
To provide leadership that helps people improve, conserve, and sustain our natural resources while educating them on the importance and practicality of maintaining our environment and quality of life.
Quick Links
Office Hours
- Monday-Friday: 8:00am - 4:30pm
- Saturday-Sunday: Closed
You must be logged in to post a comment.