The five most asked questions about soil carbon farming

Precision Pastures director and interim CEO Hamish Webb, 18/10/2022

Precision Pasutres’ Hamish Webb explains some of the ins and outs of soil carbon farming. Photo: Mike Terry

AS A relatively new industry, soil carbon farming is attracting the attention of many players in agriculture, with producers, processors, service providers, banks, investors, and retailers, all keen to understand if there is a genuine opportunity.

Drilling down into the detail is Hamish Webb, executive director and interim CEO of Precision Pastures, a specialist agronomy and carbon services business based in Armidale New South Wales. Precision Pastures conduct soil testing for carbon farming and, more generally, help farmers navigate the soil carbon industry. Mr Webb – a beef and sheep producer himself – unpacks the five most commonly-asked questions he gets about soil carbon farming.

Q: Are soil carbon levels determined by rainfall and should I undertake my baselining soil testing in a drought?

A: You will struggle to increase soil carbon without adequate rainfall however, most people are surprised to know that there is little evidence to suggest that all projects would achieve a higher soil carbon level if they were baseline tested during in the drought.

In fact, some of our recent soil carbon testing has returned lower carbon levels now, during high rainfall periods, than during the worst months of the 2019 drought.

There are many possible reasons for this, such as waterlogged anaerobic soils reducing microbial activity or ‘carbon drawdown’ as plants breakdown complex molecules and release carbon in order to access the NPK (nitrogen, phosphorous and potassium) they need. While there is some way to go to fully understand the soil carbon cycle, we believe that increasing soil carbon is a long-term objective and in our opinion, should be viewed for its production benefits and not an opportunity to outsmart the carbon measurement protocol for short term financial gain. We’ve seen a few people try and fail at that.

Q: How much does soil carbon measurement cost?

A: Precision Pastures soil baseline testing is conducted by two-to-three qualified staff, including a qualified agronomist, using a custom-built four-wheel drive or truck mounted drilling rig and GPS equipped scout buggy to minimise stock and cropping disturbance.

For this we charge $2700 per day plus travel and laboratory tests. We can usually complete at least 25 samples a day and using a ratio of one sample to 10 hectares, it would work out at somewhere around $10 per hectare. This is fairly intensive sampling, so it could be even less in some cases.

Soil carbon measurement is not the most expensive part of a soil carbon project – it is significantly less than project developer or agent commissions, the land management activities and even the ongoing management and audit costs involved.

Soil measurements are taken in accordance with strict guidelines, are highly accurate and tested by accredited laboratories, similar to mining projects who ‘prove up’ their resources. For this reason, the Australian soil carbon methodology has been ranked number one in the world for protocol rigor, which one day could deliver a higher price for soil carbon ACCUs than others. Soil testing also provides valuable soil health and production data to the farmer which can be used to solve any soil health issues and unlock any production constraints.

Q: I’ve been practising regenerative agriculture for years. Is there any upside in undertaking soil carbon project or have I missed my opportunity to receive Australian Carbon Credit Units (ACCUs)?

A: There are three key details to clarify in answering this question:

  • Are your soils saturated in carbon for your region and your soil type i.e. clay, loam, or sandy? If they’re not saturated, then there’s still upside. If you haven’t measured, you’re only guessing. For heavy basalt soils on high rainfall, we’ve seen as soil organic carbon levels increase beyond 16 per cent, down to 15cm.
  • Are there any soil health issues that, if addressed, would reasonably increase soil carbon sequestration i.e. pH, nutrient deficiencies, or toxicities? If there are, then you still have upside to increase your carbon levels. As an example, we’ve seen acidic soils increase by 0.25 per cent soil organic carbon (SOC) in just three years, just by incorporating lime at 1t/ha at depths of 10-to-50cm (tested from July 2019 to July 2022).
  • Have you tested at depth? Many people think their soil carbon levels are saturated at zero-to-10cm, but it can be a different story at 10-to-30cm and certainly at 30-to-100cm. We’re yet to see any project that is fully saturated has no upside to sequester more carbon at depth.

Q: Is there any risk that I will have a major liability to pay back if I don’t sequester any carbon?

A: One of the many differences of the soil carbon methodology compared with the vegetation method is that soil carbon credits are only issued when lab tested measurements confirm an increase in carbon termed a ‘net carbon abatement amount’. This means you cannot be issued an Australian Carbon Credit Unit (ACCU) until one tonne of carbon is tested, reported and verified.

Vegetation methods however, are modelled using assumptions and averages, which are audited years later and hence may incur a liability, if the farmer was overissued ACCUs.

Furthermore, under the soil carbon method, the Clean Energy Regulator will apply a discount to the issuance of ACCUs to account for the risk of reduction in carbon levels and-or any variance in the soil test results.

These two factors reduce the risk of liability that the landowner may have to pay back credits in the future.

Finally, many of our clients do not intend to sell their ACCUs, but rather hold onto them in their ANREU account (Australian Registry of Emission Units). This is further risk mitigation putting the farmer in the box seat to do whatever they choose in the future, to meet any requirements imposed on them by governments or to market their product in any way they choose.

Q: If I want to supply into a carbon neutral supply chain, do I need to participate in soil carbon farming on my property to do so?

A: There are other ways to become carbon neutral (such as purchasing ACCUs or offsets elsewhere), however undertaking a soil carbon project is one of the best ways a beef producer could earn offsets (ACCUs), while improving their pasture production.

This soil carbon methodology (though new and a bit complex) appears to have been designed to be a win-win for red meat producers and so far, it looks to have achieved that.

This article is part of AgCarbon Central’s Carbon Forum series. See below for more columns.



Your email address will not be published. Required fields are marked *

Your comment will not appear until it has been moderated.
Contributions that contravene our Comments Policy will not be published.


  1. Bob Shepherd, 28/10/2022

    Thank you for the article Hamish – very enlightening. Delving into your first question about rainfall and accumulating soil carbon, what are your views please, on accumulating carbon in Australia’s rangelands ie areas below 600mm annual rainfall, and the if there are possibilities for net accumulation, what are the testing options where $10/ha would be prohibitive.
    Thank you,
    Bob Shepherd
    Dept of Agriculture & Fisheries (Qld)
    Charters Towers

Get Beef Central's news headlines emailed to you -