Formula used
Pure live seed combines purity, germination, and dormant seed. Adjusted rates include planting, loss, overlap, equipment, and timing factors. Bulk seed equals adjusted target seed divided by PLS.
PLS % = Purity % × (Germination % + 0.5 × Dormant %) ÷ 100 Bulk rate = Base rate × Mix share × Adjustments ÷ PLS fraction Total seed = Bulk rate × Adjusted field acres Available N = (Biomass N + Root N) × Availability + Fixed N Net cost = Establishment cost − Estimated nitrogen value
How to use
Enter field size, crop goals, and planting method. Add one species or build a complete mixture. Review calculated seed, cost, biomass, and nitrogen estimates carefully.
- Choose the area unit and planting method.
- Select a single crop or mixture.
- Enter seed quality and field conditions.
- Add prices, dates, and management assumptions.
- Submit and review warnings before purchasing seed.
Example data
| Input | Example | Purpose |
|---|---|---|
| Field area | 20 acres | Defines total seed and cost |
| Mixture | 60% cereal rye, 40% crimson clover | Balances biomass and nitrogen |
| Planting method | Drilled | Sets application adjustment |
| Seed quality | 98% purity, 90% germination | Calculates pure live seed |
| Seed prices | £0.75 and £2.40 per pound | Estimates species costs |
Cover crop comparison
| Crop | Rate | Type | Hardiness | Biomass | Ground cover | N fixation | N scavenging | Weed control | Compaction | Pollinators | Grazing | Termination |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Cereal rye | 90 lb/ac | Grass | High | 2.4 t/ac | 92% | 0 lb/ac | 85 lb/ac | High | Medium | Low | Good | Medium |
| Oats | 80 lb/ac | Grass | Low | 1.8 t/ac | 86% | 0 lb/ac | 70 lb/ac | High | Medium | Low | Excellent | Easy |
| Wheat | 90 lb/ac | Grass | High | 2.0 t/ac | 88% | 0 lb/ac | 75 lb/ac | High | Medium | Low | Good | Medium |
| Barley | 85 lb/ac | Grass | Medium | 1.9 t/ac | 86% | 0 lb/ac | 68 lb/ac | High | Medium | Low | Good | Easy |
| Annual ryegrass | 22 lb/ac | Grass | Medium | 2.1 t/ac | 94% | 0 lb/ac | 80 lb/ac | High | High | Low | Good | Hard |
| Crimson clover | 20 lb/ac | Legume | Medium | 1.6 t/ac | 82% | 90 lb/ac | 35 lb/ac | Medium | Low | High | Good | Easy |
| Red clover | 14 lb/ac | Legume | High | 1.7 t/ac | 84% | 95 lb/ac | 32 lb/ac | Medium | Low | High | Good | Medium |
| White clover | 8 lb/ac | Legume | High | 1.1 t/ac | 88% | 75 lb/ac | 28 lb/ac | Medium | Low | High | Excellent | Medium |
| Hairy vetch | 30 lb/ac | Legume | High | 2.0 t/ac | 85% | 120 lb/ac | 40 lb/ac | High | Low | High | Limited | Medium |
| Field peas | 100 lb/ac | Legume | Low | 1.7 t/ac | 80% | 85 lb/ac | 38 lb/ac | Medium | Low | Medium | Good | Easy |
| Cowpeas | 60 lb/ac | Legume | Low | 2.2 t/ac | 84% | 95 lb/ac | 36 lb/ac | High | Low | Medium | Good | Easy |
| Buckwheat | 55 lb/ac | Broadleaf | Low | 1.4 t/ac | 90% | 0 lb/ac | 42 lb/ac | High | Low | Excellent | Limited | Easy |
| Mustard | 12 lb/ac | Brassica | Low | 1.5 t/ac | 88% | 0 lb/ac | 60 lb/ac | High | Medium | High | Limited | Easy |
| Tillage radish | 12 lb/ac | Brassica | Low | 1.8 t/ac | 82% | 0 lb/ac | 75 lb/ac | Medium | High | Medium | Good | Easy |
| Turnip | 8 lb/ac | Brassica | Medium | 1.5 t/ac | 84% | 0 lb/ac | 62 lb/ac | Medium | Medium | Medium | Excellent | Easy |
| Sorghum-sudangrass | 35 lb/ac | Grass | Low | 4.0 t/ac | 94% | 0 lb/ac | 90 lb/ac | Excellent | High | Low | Good | Medium |
Frequently asked questions
What does pure live seed mean?
Pure live seed estimates viable seed within purchased material. It combines purity, germination, and part of dormant seed. Lower PLS requires more bulk seed for equivalent stands.
Why does broadcasting require more seed?
Broadcast seed has less reliable soil contact. Surface losses and uneven placement reduce establishment. Higher rates compensate for those common field losses.
Can I calculate a multi-species mixture?
Yes, add several crops in the mix builder. Assign each species a percentage, rate, and price. Mixture percentages must total exactly one hundred percent.
How accurate is the nitrogen estimate?
The estimate uses biomass, nitrogen content, roots, and availability. Actual release depends on weather, soil, and termination timing. Confirm fertiliser credits with local agronomic guidance before application.
Does the calculator recommend planting dates?
It compares planting and first frost dates. Limited growth time increases rates and creates warnings. Local climate and crop maturity remain important considerations.
How are seed bags calculated?
Total bulk seed is divided by entered bag weight. The result rounds upward to whole bags. Supplier package sizes can still require manual adjustment.
Can grazing be included?
Yes, enter the expected biomass removal percentage. Grazing reduces residue and available nitrogen estimates. Avoid excessive removal when soil protection remains essential.
What is the carbon contribution?
Carbon contribution applies a carbon fraction to estimated biomass. It is not a verified sequestration credit. Long-term storage depends on decomposition and management practices.
Why is termination timing important?
Late termination can complicate planting and moisture management. Early termination reduces biomass and nitrogen potential. Match termination timing with crop, weather, and equipment.
Can custom seeding rates be entered?
Yes, each species row accepts a custom rate. Leaving zero uses the calculator's reference rate. Always prioritise current supplier and extension recommendations locally.
Are estimates suitable for purchasing decisions?
The calculator supports planning and scenario comparisons. Seed lots and field conditions can differ substantially. Verify final quantities with suppliers and local advisers.