# Herbicides: Emissions

Why coal-fired phosphorus makes weedkillers carbon heavy

Source page: https://www.materialinsights.org/chemicals/herbicides/emissions/

What this tab covers The greenhouse-gas footprint per tonne, split by lifecycle phase (feedstock, production, movement, use, end of life), the global total, other environmental impacts, levers and low-carbon routes, India's position, and where the investment opportunity lies. Emission intensity 20.7 kg CO2e per kg a.i. range about 10-30 depending on molecule and energy source (indicative) · 19.57 kg fossil CO2, 0.037 kg CH4 and 0.00036 kg N2O per kg a.i., converted with AR5 GWPs (CH4 28, N2O 265) Global emissions per year 40.0 Mt CO2e per year 2022 · about 1.9 Mt a.i. x 20.7 kg CO2e/kg (indicative)

Per kg of herbicide active ingredient, cradle-to-gate. Intensity: Field to Market impact factors, based on Audsley et al. (2009) and Green (1987). Global total: derived from FAOSTAT use (indicative) and Field to Market factor.

#### Share of footprint by lifecycle phase
 Feedstock 40% Production / process 54% Movement 6%

#### Footprint by lifecycle phase

| Phase | Intensity | Share | Main sources of emissions | Notes | Source |
|---|---|---|---|---|---|
| **Feedstock** | about 8 kg CO2e per kg a.i. (indicative) | 40% | yellow phosphorus (electric furnaces on coal-heavy grids), chlorine, ammonia, methanol | glyphosate's phosphorus is the biggest single feedstock burden | indicative split |
| **Production / process** | about 11 kg CO2e per kg a.i. (indicative) | 54% | multistep batch synthesis, solvent recovery, coal steam and effluent evaporation | Chinese and Indian plants mostly use coal steam (indicative) | indicative split |
| **Movement** | about 1 kg CO2e per kg a.i. (indicative) | 6% | container shipping and road distribution, including water in formulations |  | indicative |
| **Use** | outside cradle-to-gate; tractor diesel for spraying about 1-2 l/ha per pass (indicative) | – | application passes | Herbicides enable no-till, which saves fuel and may keep soil carbon; the net effect is debated | indicative |
| **End of life** | small | – | degradation in soil; plastic containers | glyphosate breaks down to AMPA; atrazine persists in groundwater | indicative |

#### Other environmental impacts

Toxicity to non-target plants and aquatic life, groundwater contamination (atrazine, metolachlor metabolites), drift damage (dicamba), human poisoning (paraquat), and herbicide-resistant weeds. Glyphosate wastewater in China is salty and phosphorus-rich.

#### Levers to cut emissions

- Precision spot spraying with cameras; John Deere reported about 59% average herbicide savings with See & Spray in 2024 (indicative)
- Low-carbon power for yellow phosphorus furnaces
- Single-isomer products such as L-glufosinate that halve the dose
- Integrated weed management: rotation, cover crops, harvest weed seed control

#### India

Indian technical plants in Gujarat and Maharashtra run largely on coal steam and grid power; companies such as UPL and PI Industries publish group Scope 1 and 2 targets in BRSR reports (indicative).
 Emission figures are indicative global averages from the life-cycle studies named; actual footprints vary widely by site, energy mix and method.

#### Low-carbon routes

| Route | Intensity | Cost premium | Status | Source |
|---|---|---|---|---|
| **Precision and robotic weeding (camera spot-spray, laser weeding)** | cuts herbicide use per hectare by half or more in trials (indicative) | high machine cost; pays back on large farms | commercial in the US, Brazil and Australia (Deere, Bilberry, Greeneye, Carbon Robotics) | indicative |
| **Bioherbicides** | not published | high | very small share; few products work at field scale | indicative |

 For a climate investor The climate lever is less the factory than the field: precision spraying, robotics and biological weed control cut volumes sprayed. In manufacturing, Indian process chemistry that cuts steps, solvents and effluent can win share from China as buyers diversify. What has to be true: registrations, reliable intermediate supply outside China, and farmers paying for precision kit.

## Other sections

- [Summary](https://www.materialinsights.org/chemicals/herbicides/index.md)
- [Overview](https://www.materialinsights.org/chemicals/herbicides/overview/index.md)
- [Correlation](https://www.materialinsights.org/chemicals/herbicides/correlation/index.md)
- [Production route](https://www.materialinsights.org/chemicals/herbicides/routes/index.md)
- [Production](https://www.materialinsights.org/chemicals/herbicides/production/index.md)
- [Feedstocks](https://www.materialinsights.org/chemicals/herbicides/feedstocks/index.md)
- [Cycles](https://www.materialinsights.org/chemicals/herbicides/cycles/index.md)
- [Trading](https://www.materialinsights.org/chemicals/herbicides/trading/index.md)
- [Movement](https://www.materialinsights.org/chemicals/herbicides/movement/index.md)
- [Regulation](https://www.materialinsights.org/chemicals/herbicides/regulation/index.md)
- [Characteristics](https://www.materialinsights.org/chemicals/herbicides/characteristics/index.md)
- [Relationships](https://www.materialinsights.org/chemicals/herbicides/links/index.md)