Tool · Nutrient planning

Manure Calculator

Manure nutrient content varies 3–5× across species, storage, and bedding — so any calculator built on “typical” values is usually wrong. This one pulls medians and variability from 554,616 real lab analyses in UMN's ManureDB, applies state-aware P-Index thresholds (PA, NY, IA, WI, OH, MI, IL, NC, MD, VA, CA, MN, NE, KS, MO, IN, TX), and returns a rate, a 3-year N schedule, structured N credits from previous crops and cover crops, NOP organic 90/120-day compliance, setback-adjusted effective acres, and full coefficient provenance.

ManureDB snapshot 2026-02-24 · CC-BY 4.0 · decision aid only — not a substitute for a certified nutrient management plan.

1 · State & manure source

Different states use different P-Index thresholds, winter spreading rules, and setback distances. Pick yours and we'll apply the right rule set; leave blank for a defensible national default (NRCS 590).

Adjusts organic-N mineralization (warm climates mineralize ~20% faster).

Open lagoons can lose 50–75% of N before application. Selecting the storage type applies the right retention factor to the lab/book values.

Based on 39 lab samples in ManureDB.

2 · Crop & yield goal

Removal coefficients: Tri-State 2020 (Bulletin 974); Ohio ANR-74 (n=2,300+ samples)

bu/acre

3 · Prior-year N credits

Each line below is added to the total N already credited to this crop. We use Penn State and Iowa State extension values for the typical credits — actual values vary.

We'll credit ~13% as Y2 carryover.

Above 21 ppm reduces sidedress need.

Irrigation water N (advanced)

Credit = ppm × 0.226 × acre-inches per acre.

4 · Soil test & application
Field context, setbacks & loads (optional but recommended)

Runoff risk scales with slope — we'll flag ≥6%.

Setback features (reduces effective acres)

Certified organic? (NOP 90/120-day rule)
Fertilizer price overrides (defaults: N $0.67, P₂O₅ $0.85, K₂O $0.45 per lb — updated 2026-03)