Manure Management Calculator

Annual production, storage sizing, nutrient content, and acreage needed for proper application. Plus regulatory thresholds (CAFO, NPDES).

Calculate

Animals

Species Dairy cow (1,400 lb) Beef cow (1,200 lb) Beef stocker (700 lb) Horse (1,000 lb) Finishing hog (200 lb avg) Sow w/ litter (450 lb) Mature sheep (150 lb) Mature goat (130 lb) Layer hen (4 lb) Broiler chicken (5 lb) Turkey (25 lb) Duck (8 lb) Rabbit (10 lb)

Animal count

Storage system Solid stack / dry lot Composted Liquid / slurry pit Anaerobic lagoon Bedded pack / deep bedding

Storage period (months) 6 months typical for fall + spring application

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 "OAT Manure Management Calculator (openagriculturetechnology.com)". Production rates from MWPS (Midwest Plan Service) Livestock Waste Facilities Handbook.