Ontario Manure Nutrient Calculator

The Ontario manure nutrient calculator tool can be accessed by clicking the icon below.

(this is the same tool previously posted on gocorn.net)

Simple Summary

  • The manure nutrient calculator can estimate the amount and value of nutrients N, P and K from manure applications
  • Manure application details (application timing, incorporation etc.) can be adjusted to reflect differences in manure nutrient availability or loss for various manure application practices

Ontario Manure Nutrient Calculator

What is the nutrient value of the manure I plan to apply? How does time of year or timing of incorporation impact my manure nitrogen credit? Will I have credits beyond just the year of application? The manure nutrient calculator provides a quick estimate of the nutrient value of manure applications and also provides scenario adjustments (time of application, incorporation etc.) to see how manure application management impacts nutrient values.

Figure 1. Screenshot of the Ontario manure nutrient calculator tool.

This manure nutrient calculator was originally created and released using the nutrient credits used in the former NMAN software. This tool can be handy for doing quick calculations and comparisons but is not as up to date as the manure nutrient values in the AgriSuite tool. Some slight differences in calculations may exist. It is suggested to use the AgriSuite tool for most up to date manure estimates (search internet for “OMAFRA Agrisuite”).

Using the Calculator

The manure nutrient calculator estimates the nutrient content and value of manure applications based on the type of manure and when and how it is applied. Data that must be entered includes:

  1. Manure nutrient analysis
    • if manure analysis is available (e.g. you have lab analysis results from your manure), values can be entered directly into the calculator
    • if you do not have a manure nutrient analysis, you can select the manure from the manure database that best represents the manure you will be applying (estimates analysis based on database from Ontario labs)
  1. Manure application details
    • manure application details (application rate, time of year, incorporation timing, residue cover in field) are included to adjust credits for nutrient release and losses relative to the next crop(s) being grown, for example:
      • manures with high organic-N content (e.g. solid beef manure) need time to breakdown and mineralize N and will provide the best nitrogen credit for corn if applied the fall before a corn crop
      • manures with high inorganic-N content (e.g. liquid swine manure) are mostly in available form and will provide the greatest N credit (least amount of loss) if applied in the spring the corn crop is to be planted
      • manures with high ammonium content that are injected or incorporated as soon as possible after application will limit volatilization losses and provide the greatest N credit
  1. Value of fertilizer nutrients
    • The fertilizer values of urea, MAP and potash are entered to provide fertilizer-replacement values of N, P and K in the manure


After the above information has been entered, the tool will provide the manure nutrient credits (lb/ac), and estimated manure nutrient values ($/ac) for:

  • Nitrogen, for the next four cropping season
  • Phosphorous, for the next two cropping season
  • Potassium, for the next cropping season