How to Use Compost and Manure in Fall Beds
Spread about 1 inch of compost on vegetable beds in fall and work it into the top 6 to 8 inches. Add raw manure in fall too, at least 120 days before harv...
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How to Use Compost and Manure in Fall Beds
Spread about 1 inch of finished compost over empty vegetable beds this fall and mix it into the top 6 to 8 inches. University of Maryland Extension says 1 inch per year maintains garden productivity. If you have raw manure, fall is also the time to add it.
Check the Soil Test Desk first. Add lime or other amendments before the compost, based on your soil report.
How Much Compost
Extension recommendations differ by climate and compost type, so treat 1 inch as a safe middle.
| Source | Established vegetable beds |
|---|---|
| University of Maryland Extension | About 1 inch per year |
| Colorado State Extension | 1 to 2 inches of plant-based compost. Half an inch if the compost contains manure or biosolids |
| Oregon State Extension | 1/4 to 1 inch per year |
New beds can take more. Colorado State suggests 2 to 3 inches of plant-based compost for the first three years. Oregon State suggests 3 to 4 inches for a brand new bed.
How Much Is That
- 8.33 cubic feet of compost covers 100 square feet 1 inch deep (University of Maryland Extension).
- A 1 cubic foot bag covers 12 square feet 1 inch deep (Oregon State Extension).
- 3 cubic yards covers 1,000 square feet 1 inch deep.
How to Apply It
- Pull spent plants and clear the bed.
- Spread the compost evenly across the surface.
- Spread lime or other amendments recommended by your soil test.
- Fork or till everything into the top 6 to 8 inches. Colorado State says do not leave compost in chunks, because it blocks root growth and water movement.
- Cover with shredded leaves or sow a cover crop. See the Fall Leaves Desk and which cover crop for spent beds.
UC Marin Master Gardeners say a fall application is best for improving soil structure.
Manure
- Treat any local manure as uncooked. University of Maryland Extension says to add it in the fall, and cover the soil with leaves if possible to limit runoff and erosion.
- Observe the harvest wait. The USDA National Organic Program requires raw manure to go on at least 90 days before harvesting a crop whose edible part does not touch the soil, and at least 120 days before a crop that does. Raw manure worked in this October clears both windows for next spring's crops.
- Use less of manure-based compost. Colorado State says not to add more than 1 inch of manure or biosolid compost in a season without a soil test, because salts can build up.
- Never use pet waste in a vegetable bed.
What Compost Will Not Fix
Compost adds organic matter and some nutrients. It does not replace a soil test. It will not correct a low pH. If your pH is low, you still need lime at the lab's rate, which you can find in how to read your soil test results.
Next Steps
- Test the soil if you have not in the last 2 years: how to take a garden soil sample.
- Add lime if the lab says so: when and how to add lime in fall.
- Spread compost and mulch or sow a cover crop.
- Check off the task on Garden to Bed.
Sources
- University of Maryland Extension, Organic Matter and Soil Amendments
- Colorado State Extension, Vegetable Gardens: Soil Management and Fertilization
- Oregon State Extension, How to Use Compost in Gardens and Landscapes (EM 9308)
- UC Marin Master Gardeners, How to Use Compost
- USDA Agricultural Marketing Service, National Organic Program, 7 CFR 205.203
To work out how much compost a top-up takes, use the Raised Bed Desk.