Manure Management.
Manure Management Calculator
Annual production, storage sizing, nutrient content, and acreage needed for proper application. Plus regulatory thresholds (CAFO, NPDES).
Manure as fertility
| Species | Daily manure (lb / 1000 lb animal) | NPK (% as-is, dry stack) |
|---|---|---|
| Dairy cow | ~80 lb fresh | 0.5 / 0.2 / 0.5 |
| Beef cow | ~60 lb | 0.6 / 0.2 / 0.5 |
| Horse | ~50 lb | 0.7 / 0.3 / 0.6 |
| Pig (finishing) | ~70 lb | 0.5 / 0.4 / 0.5 |
| Sheep / goat | ~40 lb | 0.7 / 0.3 / 0.7 |
| Layer chicken | ~60 lb (per 1000 lb live wt) | 1.5 / 1.4 / 0.6 (high-N) |
| Broiler chicken litter | ~80 lb | 3.0 / 3.0 / 2.0 (very high-N) |
| Turkey litter | ~70 lb | 2.5 / 2.5 / 1.7 |
| Rabbit | ~30 lb | 2.4 / 1.4 / 0.6 (excellent) |
Poultry litter is the most concentrated; horse + cow are the most volume-heavy.
Application rate guidance
Manure application rates are usually limited by the most-restrictive nutrient, typically phosphorus on most modern farms because long-term manure application has built up soil P.
| Nutrient basis | Typical application rate | Use when |
|---|---|---|
| Crop N requirement | 15-25 tons/acre solid manure (cow); 5-10 tons (poultry) | P levels low; need lots of N |
| Crop P requirement | 5-10 tons/acre (cow); 1-3 tons (poultry) | Standard most farms; soil P optimum |
| P-index "high" | 0 (no manure) or remove | Soil test high; runoff risk |
Rule of thumb: ~5-10 tons/acre solid bovine manure annually meets corn N needs without overloading P. Always do a soil test before establishing rate.
Regulatory considerations
| Threshold | Designation | Implication |
|---|---|---|
| 1,000+ AU (Animal Units) | Large CAFO | EPA NPDES permit required; nutrient management plan; stormwater controls; comprehensive recordkeeping. Approximately: 1,000 cattle, 700 dairy, 2,500 finishing hogs, 125,000 broilers |
| 300-999 AU | Medium CAFO (only if direct discharge) | Permit if discharging |
| Below 300 AU | Small CAFO (only if designated) | State + local rules apply |
| Any size + setbacks | State agency rules | Most states require setbacks from neighbors, water bodies, public roads. Verify locally. |
If approaching CAFO thresholds: plan ahead. State environmental agencies often offer pre-permit planning meetings. Late compliance is expensive.
Storage standards
| System | Volume needed (per AU per month storage) |
|---|---|
| Solid stack (covered) | ~10 cu ft per animal unit per month |
| Solid stack (uncovered, factor in rainfall) | +30-50% volume for rain runoff |
| Bedded pack (deep bedding) | ~25 cu ft per AU per month |
| Liquid pit | ~40 gal per AU per day = 1,200 gal per AU per month |
| Anaerobic lagoon | Larger (1.5-2× liquid pit); plus volatile solids storage |
Free under CC BY 4.0. Cite as "Open Agriculture Technology Manure Management Calculator (openagriculturetechnology.com)". Production rates from MWPS (Midwest Plan Service) Livestock Waste Facilities Handbook.