AGRONOMIC RESOURCE

Plant Available Nitrogen Calculator

Calculate how much of the nitrogen you apply may actually be available to the crop—and what that available nitrogen really costs.

Fertilizer inputs

Enter the fertilizer information

Select a fertilizer material. The calculator will automatically use the correct dry or liquid calculation method.

Fertilizer material

Material form

Reference C:N ratio

Typical or measured reference value.

Total nitrogen (%)

Use the nitrogen percentage shown on the product label.

Product weight (lb per gallon)

Use the density or pounds-per-gallon value shown on the product label or technical data sheet. A reference value is supplied when available.

Pounds applied

Price per pound ($)

Biological assumptions

Microbial C:N ratio

Carbon used for new tissue (%)

Estimated results

Plant Available Nitrogen

Estimated nitrogen remaining after modeled microbial immobilization.

Plant Available Nitrogen

—

pounds of estimated PAN

In-season efficiency —

Cost per PAN lb —

Reference C:N used —

Material weight represented —

Total nitrogen applied —

Estimated total carbon —

Carbon used for new tissue —

Estimated N immobilized —

Total material cost —

What does this number mean?

Total nitrogen on a fertilizer label does not necessarily describe how much nitrogen may be available to the crop during the growing season. Carbon associated with a fertilizer can influence microbial nitrogen immobilization. Liquid products are converted from gallons to pounds using the product's weight per gallon before nitrogen is calculated.

C:N Reference Guide

Common Fertilizer C:N Ratios

These values are general reference points for comparison. Actual C:N ratios can vary by raw material source, processing, formulation, and manufacturer. When available, use a current laboratory result or technical analysis for the exact fertilizer being evaluated.

Typical carbon-to-nitrogen ratios for common fertilizer materials
Material	Typical C:N Ratio
Blood meal	~3:1
Feather meal	~4:1
Meat & bone meal	~4:1
Bone meal	~4:1
Soy meal	~5.5:1
Corn steep liquor	~5:1
Poultry litter	~12.5:1
Natural Ammonia	0:1
Phytamin® Jumpstart	~2.30:1

Best practice: If you have a laboratory C:N result for the exact fertilizer being evaluated, use that value instead of the reference table.

Reference C:N and density values are comparison values and may vary among manufacturers, feedstocks, formulations and production processes. When available, use the actual product label, technical data sheet or laboratory analysis. Actual nitrogen availability is also influenced by soil temperature, moisture, microbial activity, placement, application timing and other field conditions. This calculator is an educational planning and comparison tool, not a guarantee of crop nitrogen availability.