Cover Crop Seed & Build the Right Mix
Blends legume
Build a legume–grass–brassica mix from each species' solo rate and its share to get the seeding rate in kg/ha, per-species amounts and total seed for your field.
Build your mix
Next: aim for proportions that sum to ~100%; drill or broadcast 47 kg/ha and roll/incorporate before the cash crop.
Solo rates are typical; adjust for sowing method, seedbed and goals (grazing, green manure, soil cover).
Cover crop seed — key facts
- Mix rate
- Σ (solo rate × share)
- Legume
- fixes nitrogen
- Grass
- biomass & soil structure
- Brassica
- breaks compaction
- Shares sum to
- ≈ 100%
- Establish
- drill or broadcast
- Then
- roll / incorporate
- Privacy
- Runs in your browser; nothing uploaded
One mix, three jobs for your soil
A diverse cover crop does more than a single species ever could: the legume fixes nitrogen for the next crop, the grass piles on biomass and binds the soil, and the brassica drives a taproot through the hardpan. The trick is the rate — grown together, each species needs only a slice of its solo seeding rate, so you weight each one by its share of the mix and add them up. Get the blend right and you grow more soil health for the same seed cost.
This tool computes the mix seeding rate in kg/ha, each species' kg/ha, the total seed for the field and a percentage-sum check from your solo rates and shares. Use it to design a balanced blend, order the right amount of each seed, and avoid an over- or under-sown stand. Pair it with the Green Manure, Seed Rate and Crop Rotation tools to plan your soil-building season.
Balance the blend
Weight each species by its share of the mix.
Order the right seed
Per-species and total amounts for the field.
Check it sums
Live % keeps the blend near 100%.
Build soil three ways
Nitrogen, biomass and decompaction in one.
Frequently Asked Questions
What is a cover crop seed mix?+
A cover crop mix combines two or more species so each does a different job for the soil — typically a legume to fix nitrogen, a grass for biomass and soil structure, and a brassica to break up compaction. Because they grow together, each species is seeded at only a fraction of its solo (monoculture) rate so the stand isn't overcrowded.
How is the mix seeding rate calculated?+
For each species you take its solo seeding rate and multiply by its share of the mix, then add them up: mix rate (kg/ha) = Σ (species solo rate × its % in mix). For example a grass at 100 kg/ha solo, used at 50% of the mix, contributes 50 kg/ha; add the legume and brassica contributions for the total mix rate.
What does each species do in the mix?+
The legume fixes atmospheric nitrogen, feeding the next crop. The grass produces bulk biomass, holds soil, scavenges nutrients and adds organic matter. The brassica sends down a strong taproot that breaks compaction and opens channels for water and air. Blending them gives benefits no single species delivers alone.
Should the proportions add up to 100%?+
Yes — the species shares should sum to about 100% of the mix. The tool shows the running percentage so you can see whether your blend is balanced; if it's well under or over 100%, adjust the shares. The proportions decide how much of each species' solo rate ends up in the field.
How do I set the proportions?+
Lead with whatever goal matters most: more legume for nitrogen, more grass for biomass and erosion control, more brassica for busting compaction. A common balanced blend is roughly equal thirds, but tilt it toward your aim. The shares simply weight each species' solo rate in the final mix.
How do I get the total seed for my field?+
The tool multiplies the mix rate (kg/ha) by your field area to give the total seed to buy, and also breaks it down per species so you can order each one. Enter area in hectares or acres and it scales the per-species and total amounts to match your field.
Drill or broadcast — does it matter?+
Both work. Drilling places seed at consistent depth for reliable germination and often lets you trim the rate slightly. Broadcasting is faster but usually needs a higher rate and good seed-to-soil contact — broadcast onto a firm bed, then roll or lightly incorporate. Whichever you choose, follow with rolling or incorporation before the cash crop.
When do I terminate the cover crop?+
Terminate before it competes with or sets seed ahead of the cash crop — usually by mowing, rolling/crimping, grazing or incorporation. Roll or incorporate the residue ahead of planting so it breaks down and releases nutrients. Earlier termination favours a clean seedbed; later termination grows more biomass and nitrogen.
Are the seeding rates exact?+
They're solid planning rates. Real rates depend on seed size and quality, sowing method, seedbed, sowing date and your soil-building goal. Use the calculated mix as a starting point, check germination on the seed tag, and adjust — a slightly generous rate is cheap insurance for a thick, weed-suppressing stand.
Can I use it for any cover crop species?+
Yes — enter each species' own solo seeding rate and its share of the mix and it works for any blend, whether two species or a diverse polyculture of legumes, grasses, brassicas and broadleaves. The math is the same; the tool just sums each species' weighted contribution into the mix rate.