This is the Perfect year to start Cover Crops!

For new adopters, it is best to start simply.

Cover crops are non-cash crops planted between growing seasons to improve and protect your soil. They offer a low-risk way to build soil health, improve water retention, and support long-term productivity.

Key Benefits of Cover Crops

Excess Nutrient Uptake – Cover crop plants will absorb the excess nitrogen in the soil and store it in their leaves. They release the nutrients slowly back into the soil as they degrade.
Erosion Control – Protects topsoil from wind and water erosion.
Weed Suppression: Outcompetes weeds in fall and spring and provide ground cover to suppress weed germination.
Water Infiltration – Improves soil structure, develops channels for infiltration, and therefore reduces runoff.
Compaction Relief – Taproots like radish can penetrate tight soils and improve porosity.
Add Organic Matter – Increased organic matter will help hold moisture, retain nutrients, increase aggregate stability and make a field more resilient to weather extremes.

Let’s talk about Biology

Besides the agronomic benefits, there are also biological reasons that make cover crops especially valuable.

Biological Benefits to Soil Health

Feed the Soil Microbiome

Plant roots exude sugars, amino acids, and organic acids into the rhizosphere (root zone), which stimulate microbial growth.
Cover crops keep roots in the ground longer, providing food for beneficial bacteria and fungi during fall and early spring—when biology is otherwise dormant.

Jumpstart Dormant Microbes

In low-biology soils, especially those with heavy synthetic inputs, microbial activity may be suppressed.
Cover crops act like a wake-up call to sleepy soils, reactivating biological nutrient cycling and organic matter decomposition.

Build Fungal Networks

Fibrous-rooted grasses (e.g., oats, cereal rye) and taproot species (e.g., clovers, radish) support different microbial communities.
Legumes and diverse mixes foster mycorrhizal fungi that expand root access to nutrients and water.

Improve Soil Aggregation

Microbes produce glues like glomalin that bind soil particles into stable aggregates.
Better aggregation = improved water infiltration, reduced crusting, and less erosion.

Support Natural Nutrient Cycling

Cover crops scavenge leftover nitrogen and other nutrients, keeping them in the root zone.
As plants decay, microbes recycle nutrients into plant-available forms—reducing your fertilizer needs over time.

Bottom Line for New Users

If you are new to cover crops, starting simply is key. Consider a cover crop that will be killed by the cold winter temperatures (winterkill). Some species that will work well in Iowa include:

Type of plants	Species	Seeding Rate (lb/acre)	Role / Benefit
Grass	Oats	30–40	Fast-growing, good root biomass, good weed suppression
Legume	Berseem clover or Crimson clover	5–8	Adds nitrogen, feeds microbes with root exudates
Brassica(s)	Radish (Daikon type)	2–4	Deep taproot to reduce compaction,
	Rapeseed	2-4	Deep taproot to reduce compaction.
	Turnip	2-4	Fast growing, strong taproot.

A suggestion of a Winter-Kill Cover Crop Mix for Central Iowa is:

Oats – 32lbs/acre
Daikon Radish – 1 lb. per acre.
Turnip – 1 lb. per acre.
Rapeseed – 1 lb. per acre.
(optional) Clover (Berseem or Crimson clover) – 1.5 lbs/acre

Why This Mix Works

Quick Fall Growth: Oats, radish, and clover germinate and grow quickly in late summer/early fall.
High Root Exudation: Radishes and clovers “feed” microbes in the rhizosphere, critical for waking up “sleepy” soils.
No Spring Termination Needed: All species winterkill reliably in Central Iowa (USDA Zones 4–5), leaving a manageable residue for cash crop planting.
Balanced C:N Ratio: Prevents tie-up of nitrogen while still building organic matter.
Taproots & Fibrous Roots: Improve water infiltration and soil structure.

When to Plant

Optimal seeding window: Mid-August to early September
Earlier is better – The earlier you plant, the better growth, biomass and biological stimulation will take place.

Tips for Success

Broadcast cover crop seeds into standing crops (corn or soybeans) or drill them in after an early harvest of silage or small grains. Consider aerial application with a plane or drone. Also, highboy seeders would work well to ensure that the seeds reach the ground for germination.
Avoid over-applying nitrogen during establishment
Consider adding a biological stimulant (e.g., fish hydrolysate or compost extract) to prime the soil if biological activity is extremely low.

Final Thought

You’re not just planting a secondary crop – you’re laying the groundwork for healthier, more resilient soils that will benefit you for years to come. By holding valuable nutrients in the field and keeping them out of surface water, you’re also saving money on future fertilizer applications while protecting water quality.

Cover Crop Funding Assistance

Cover crop funding assistance is available in Iowa through the Water Quality Initiative (WQI) at the Iowa Department Agriculture and Land Stewardship. Contact your local Soil and Water Conservation District (SWCD) or Natural Resource Conservation Service (NRCS) office to sign up.