Soil Health · February 2025 · 6 min read
On-farm composting transforms livestock manure, crop residues, and other organic waste into a stable, nutrient-rich soil amendment. Properly made compost improves soil structure, adds slow-release nutrients, and reduces the volume of raw waste that needs handling. With the right method and management, composting is a practical addition to any farming operation.
The C:N ratio of your feedstock mix is the most important factor controlling decomposition speed and quality. Aim for a starting ratio of 25:1 to 30:1 carbon to nitrogen by weight.
Windrow composting involves forming long rows 4 to 8 feet tall and 12 to 16 feet wide, turned regularly with a loader or dedicated windrow turner. This is the most common farm-scale method and works well for large volumes of material.
Aerated static piles use perforated pipes and blowers to force air through the pile without turning. This method requires less equipment but more infrastructure. It works especially well for odor-sensitive situations and produces consistent results with less labor.
Monitor internal pile temperatures with a 36-inch compost thermometer. The pile should heat to 131 to 160 degrees Fahrenheit within the first week, which kills weed seeds and pathogens. Turn the pile when temperatures exceed 160 degrees or begin to drop below 110 degrees.
For windrows, a typical schedule is turning every 3 to 5 days during the active phase, then weekly as temperatures stabilize. The entire process takes 3 to 6 months depending on materials and management. Finished compost is dark, crumbly, and smells like earth.
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Try the Soil Test InterpreterApply finished compost at 2 to 5 tons per acre for field crops and up to 10 tons per acre for horticultural crops. Base rates on a compost nutrient analysis, crediting the available nitrogen, phosphorus, and potassium toward your fertilizer plan.
Fall application gives compost time to integrate with the soil before spring planting. Avoid applying immature compost, which can tie up soil nitrogen and may contain viable weed seeds. A simple maturity test is the bag seal test: if a sealed bag of moist compost develops no off-odor after a week, it is ready to use.