In 2025, SUL4R-PLUS partnered with Tunley Environmental to measure SUL4R-PLUS carbon footprint.

What is a carbon footprint?

Greenhouse gas emissions are commonly created when fuel and energy are used to power things. For example, burning fossil fuels such as coal, natural gas, or gasoline to create heat, electricity, and fuel vehicles leads to greenhouse gas emissions. A carbon footprint describes the amount of greenhouse gases that are created when things are manufactured. A carbon footprint can generally be broken into three stages:

  • Raw Material Extraction: this includes all the greenhouse gases created to harvest ingredients from their sources.
  • Raw Material Acquisition: this includes all the greenhouse gases created during the transport of ingredients from their sources to the point of production.
  • Manufacturing: this includes all the greenhouse gases that are created during production.

What is SUL4R-PLUS carbon footprint and how does it compare to other fertilizers?

Compared to a dozen other commonly used fertilizers, SUL4R-PLUS has the third lowest carbon footprint (Figure 1). Of these, SUL4R-PLUS carbon footprint is 34% – 81% less than the ten fertilizers that have a greater carbon footprint.

Figure 1: This figure demonstrates the cradle-to-gate carbon footprint of commonly used fertilizers as reported in published literature. Reported units were all converted to pounds of CO2 equivalents per pound of fertilizer produced. In cases where multiple sources reported the same fertilizer, values from the most recently published source were used. References to the data used in this figure are cited below in Table 1.

It’s also important to recognize that each fertilizer’s carbon footprint is unique because they each require different ingredients and processes to create the final product. For SUL4R-PLUS, more than 60% of its carbon footprint comes from creating its main ingredient: flue gas desulfurization gypsum.

Flue gas desulfurization gypsum, or FGD gypsum, is a waste product created when coal-fired power plants scrub sulfur-based gases from smokestacks. Per federal regulations, these sulfur-based gases must be scrubbed out of smokestack exhaust to prevent harmful environmental effects like acid rain. Even if SUL4R-PLUS was not on the market, the FGD gypsum would still be produced and would keep creating greenhouse gas emissions to keep the smokestacks free of sulfur oxide gases.

SUL4R-PLUS makes use of this waste product and turns it into a valuable plant-available nutrient source that can enhance crop growth and productivity. Learn more about our Research and the impact that SUL4R-PLUS can have on a variety of crop yields.

Table 1: Citations to the data referenced in Figure 1.

FertilizerCitationReference in Text
SUL4R-PLUSTunley Environmental, 2025Table 2, page 9
Ammonium Sulfate
Ammonium NitrateFertilizers Europe, 2018Table 6, page 13
Calcium Ammonium NitrateTable 8, page 15
UreaTable 10, page 17
UAN 30Table 12, page 19
Ammonium NitrosulfateBretrup and Hoxha, 2016Table 3, page 5
Calcium Nitrate
Diammonium Phosphate
NPK (15-15-15)
Triple Super Phosphate
Muriate of Potash
Anhydrous AmmoniaLiu et al., 2020Figure 4, page 7
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