Fertilizer Impact Factors Calculator

Quick User Guide

How to use the Excel-based fertilizer impact factors calculator.

Published

August 26, 2026

File: fertilizer_impact_factors_CO2e.xlsx
Version: 1.0
Last updated: August 2026

1. What this tool does

This workbook converts published greenhouse gas emission factors for 30 fertilizer products into a single number: kilograms of carbon dioxide equivalent (kg CO₂e) per unit of fertilizer.

The manufacturing of fertilizers releases several greenhouse gases, and each one warms the planet by a different amount. To add them together, each gas is multiplied by a conversion factor called a Global Warming Potential (GWP). The workbook does this for you, and lets you switch between the different published sets of GWP values with a dropdown.

You can also enter an application rate — say 150 kg per hectare — and see the total emissions at that rate.

Who this is for: Fieldprint Platform users who want to see the impact of the various fertilizer options.

2. Before you start

Open it in Microsoft Excel or LibreOffice Calc. The dropdown menus and formulas work in both.
Google Sheets: the calculations work when you import the file, but the dropdown lists may not carry across. If they don’t, type the option exactly as written in Section 4 instead of picking from a list.
Nothing is locked. You can edit any cell. If you break something, download a fresh copy.
Everything recalculates automatically. Change one input and every affected number updates immediately.

3. Quick start (three steps)

Go to the Settings tab. There are exactly three cells you need, all highlighted in yellow:

Cell	What to do
B3	Pick which set of GWP values to use (dropdown)
B4	Pick the time horizon (dropdown)
B5	Type your application rate

Then go to the Impact Factors tab and read your results.

That’s it. Everything else on the Settings tab is reference information.

4. The three inputs explained

Assessment Report (Settings B3)

The Intergovernmental Panel on Climate Change (IPCC) publishes updated GWP values every several years, in documents called Assessment Reports. Newer reports reflect better science, but many reporting programs still require an older set for consistency with past years. Your options:

Option	When you’d use it
AR6	The most recent IPCC values (2021). Use this unless a program tells you otherwise.
AR5 (with climate-carbon feedback)	Includes an additional warming effect from carbon cycle responses. Higher values.
AR5 (without climate-carbon feedback)	The more commonly used AR5 set.
AR4	Older values (2007), still required by some greenhouse gas reporting programs.

Default: AR6.

Time Horizon (Settings B4)

GWP asks “how much warming does this gas cause compared to CO₂?” — but the answer depends on the period you measure over. Methane is short-lived and hits hard early, so it looks much worse over 20 years than over 100.

Option	When you’d use it
100-yr	The standard for nearly all greenhouse gas accounting and reporting.
20-yr	Occasionally used to highlight near-term methane impacts.

Default: 100-yr. Use this unless you have a specific reason not to.

Default application rate (Settings B5)

How much fertilizer is applied. The default is 1, which means the results show emissions per single unit — the standard way to express an emission factor.

Change it to your actual rate (for example, 150) and the workbook shows total emissions at that rate.

Read the units

The rate is in whatever unit column B of the Impact Factors tab lists for that row. Most rows are kg fertilizer, meaning kilograms of the actual product. But three rows are nutrient-based: entering 150 on the “US average nitrogen fertilizer” row means 150 kg of nitrogen, not 150 kg of product. See Section 7.

5. Reading your results (Impact Factors tab)

Each of the 30 rows is one fertilizer product. Here’s what the columns mean, left to right:

Identifying the product

Column	Meaning
A — Source Detail	The fertilizer product name
B — Unit	What one “unit” of this product is. Read this before entering a rate.
C — System Boundary	How far up the supply chain the numbers reach. All rows are cradle-to-processing gate: everything from raw material extraction through manufacturing, but not transport to the field or field application.

The raw emission factors (from the source data)

Column	Meaning
D, E, F	Kilograms of each gas released per unit: carbon dioxide, methane, and nitrous oxide. These are shown in scientific notation because some are very small numbers.

The conversion to CO₂e

Column	Meaning
G, H, I	Each gas after multiplying by its GWP. This is where you can see which gas dominates a given product.
J — Total GHG (kg CO₂e/unit)	The main answer. G + H + I. This is the emission factor for one unit of the product.
K — Energy Use (MJ/unit)	Energy consumed making one unit, in megajoules. See the note in Section 7.

Applying a rate

Column	Meaning
L — Application Rate	Defaults to whatever you set in Settings B5. You can overwrite any single row — see below.
M — GHG at Rate (kg CO₂e)	Column J × column L. Total emissions at your rate.
N — Energy at Rate (MJ)	Column K × column L.

Where the numbers came from

Column	Meaning
O, P	The published source for each row’s emissions and energy figures.

Giving one product its own rate

Every cell in column L starts out following the Settings B5 default. To give a single product a different rate, just type a number over that cell. That row switches to your number; every other row keeps following the default.

If you want it to follow the default again, type =Settings!$B$5 back into the cell — or download a fresh copy.

Finding a product quickly

Row 4 has filter arrows. Click the arrow on column A to search for or select specific products. Columns A, B and C stay visible when you scroll right.

6. Worked example

Question: What are the emissions from applying 150 kg/ha of ammonium nitrate?

Open the Settings tab.
Leave B3 on AR6 and B4 on 100-yr.
Type 150 into B5.
Go to Impact Factors and find the “Ammonium nitrate” row.

Reading across that row:

Column J shows 1.4465 kg CO₂e per kg of ammonium nitrate.
Column M shows 216.98 kg CO₂e — the total for 150 kg.
Column N shows 2,204.8 MJ of energy for the same 150 kg.

Now test how much the GWP choice matters. Go back to Settings B3 and switch it to AR4. Column M becomes 226.69 kg CO₂e — about 4.5% higher, because AR4 assigns nitrous oxide a higher GWP.

Now set B3 back to AR6 and switch B4 to 20-yr. It jumps to 265.35 kg CO₂e, because methane counts far more heavily over 20 years.

This is exactly what the toggle is for: the same underlying measurements, reported three different ways, all defensible depending on which standard you’re following.

7. Things to watch out for

Product weight vs. nutrient weight. Three rows are measured per kilogram of nutrient, not per kilogram of product:

Row	Unit
K₂O	kg K₂O
US average nitrogen fertilizer	kg N
US average phosphate fertilizer	kg P₂O₅

Every other row is per kg of the physical product. Always check column B before entering a rate. Mixing these up is the easiest mistake to make with this workbook, and it produces answers that are wrong by a factor of two or more.

Sulfur: elemental sulfur is 100% S, so a kilogram of product is a kilogram of nutrient either way.

Urea shows a negative CO₂ number. This is correct, not a bug. Manufacturing urea chemically captures CO₂ into the urea molecule, so the production-stage carbon balance is negative. That CO₂ is released later when the urea is applied to soil and breaks down; field application emissions are outside this workbook’s system boundary. The Fieldprint Platform accounts for urea carbon release with the method CO₂ from urea fertilizer.

Energy is not converted to CO₂e. Columns K and N report energy in megajoules and stay there. The emissions from producing that energy are already counted in the GHG columns, so converting the megajoules to CO₂e and adding them would double count. Use the energy columns for energy reporting, not as an input to the carbon number.

Gases not in this dataset. The GWP Factors tab lists seven gases relevant to production agriculture. Fertilizers report only three of them (CO₂, methane, nitrous oxide); NF₃ and SF₆, for instance, reach a Fieldprint only through electricity generation.

8. Color key

What you see	What it means
Yellow fill, blue text	An input. Edit these.
Blue text	A fixed value from the source dataset.
Black text	A formula calculating on that same tab.
Green text	A formula pulling a value from a different tab.

9. The other two tabs

You don’t need these for normal use, but they’re there so the calculation is fully auditable.

GWP Factors — Shows the seven GWP values currently active based on your Settings choices (columns A and B), and the complete published IPCC table for all four assessment reports and both time horizons (columns Q through T, off to the right). If you want to check a number against the IPCC source, this is where.

Source Data — The original input dataset, completely unmodified. Includes the fertilizer composition fractions (nitrogen proportion, P₂O₅ fraction, sulfur fraction, and so on) that aren’t shown on the main tab.

10. How the calculation works

For each fertilizer:

kg CO2e per unit  =  (kg CO2  × GWP of CO2)
                   + (kg CH4  × GWP of CH4)
                   + (kg N2O  × GWP of N2O)

kg CO2e at rate   =  kg CO2e per unit × application rate

The GWP values are pulled from the IPCC table using whichever assessment report and time horizon you selected. Nothing is hard-coded; every result traces back to the Settings tab and the source dataset.

To illustrate with AR6, 100-year values: one kilogram of nitrous oxide counts the same as 273 kilograms of CO₂, and one kilogram of fossil methane counts as 29.8 kilograms of CO₂.

11. Troubleshooting the calculator

The numbers didn’t change when I picked a different report.

Some products emit almost entirely CO₂, which has a GWP of 1 in every report. Those rows genuinely won’t move much. Try ammonium nitrate or potassium nitrate: both are nitrous-oxide-heavy and shift noticeably.

I get an error message in a cell.

Something got overwritten. Download a fresh copy from the source page.

The dropdown lists are missing.

You’re probably in Google Sheets or a mobile viewer. Type the option text exactly as listed in Section 4 instead.

A rate I typed didn’t take effect.

Check you typed it into column L on the Impact Factors tab, not column K or M. Column M is a formula and typing over it breaks that row.

My answer looks about ten times too big or too small.

Almost certainly a nutrient-vs-product unit mismatch. See Section 7.

12. Sources

Item	Source
Fertilizer emission and energy factors	`fp5-factors-fertilizers.csv`, the fertilizer rows of the Fieldprint Platform’s authority table. Underlying sources are listed per row in columns O and P of the Impact Factors tab, and include GREET FD-CIC 2023, Fertilizers Europe, Ecoinvent, USLCI, and USDA Fertilizer Use.
Global warming potentials	`fp5-GWP.csv`. IPCC Fourth, Fifth and Sixth Assessment Reports, 100-year and 20-year horizons.
System boundary	Cradle-to-processing gate for all rows. Excludes transport to field and field application emissions.

13. Questions

Contact the Field to Market Science and Technology team (science@fieldtomarket.org).

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