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29 Mar 2023

An Agronomist's View on Enhanced Weathering - UNDO

Through enhanced weathering, we are committed to removing 1 billion tonnes of carbon dioxide by 2030. It’s an ambitious target and to achieve it, we need to work with farmers and landowners. Here we interview Jez Wardman and Ryan Pape, UNDO’s two senior agronomists with a collective 50+ years of experience, to get their views on enhanced weathering and its potential. Their focus is on developing trials to test various hypotheses, among them:
  • The effect silicate rock has on soil pH and how it could be used in place of lime to manage soil pH
  • How basalt rock increases the presence of various nutrients and the impact this may have on reducing farmer reliance on other inputs
  • Does enhanced weathering help improve the organic matter in soil?

Why should we care about enhanced weathering?

Ryan: There’s plenty of scientific literature out there extolling the virtues of enhanced weathering as a carbon removal tool. Jez: Yes, it’s considered a much more permanent way of removing carbon from the atmosphere than planting trees, since the carbon is stored for thousands of years whereas a tree only stores the carbon for its lifetime. Ryan: The exciting thing about the technique is that it has the potential added benefit of improving soil nutrient load and pH along with the carbon removal.

How will you be supporting the growth of enhanced weathering?

Ryan: Despite the evidence in literature that shows the benefits of enhanced weathering, for farmers to trust it, they want to see local field results. A huge part of what we do is translating lab results into results in the field. I am hugely passionate about the trials process – taking the science into the field. It’s what farmers expect, data produced in the field, in their growing environment.

What will the focus of the trials be?

Jez: I’m already working closely with local farmers, research organisations and independent agronomists to establish various trials to demonstrate the agronomic benefits of enhanced weathering to soil health. There is so much potential in enhanced weathering for farmers. I’m particularly interested in exploring how spreading basalt rock can help maintain the soil pH at the correct level. At the moment, if farmers identify a drop in soil pH, they’ll spread lime – that’s the accepted practice. But I really think spreading basalt rock could have a slow-release effect, preventing the soil pH level from dropping in the first place. Farmers then benefit in two ways (1) lime cost savings, and (2) avoiding yield sacrifices linked to a drop in soil pH. Ryan: In my area soil pH is very acidic in places, so economically managing soil pH is a regular concern for farmers. We’re undertaking trials to explore how soil pH responds to our crushed basalt rock, with the ultimate goal to reduce or eliminate the need for other liming agents, providing a cost and crop benefit.

What does your crushed basalt rock contain?

Ryan: UNDO work closely with quarry partners to screen the silicate rock we source. We are checking for two things:
  1. Level of heavy metals in the rock to ensure it’s safe for agricultural use
  2. Constituent minerals; both for nutrients and to maximise the weathering reaction.
Jez: It is crucial that we source basalt rock that is safe for use on agricultural land, which is why we screen so carefully. But by screening the rock, we can also provide farmers with detail on what additional nutrients they will be adding to their soil. Silicate rock acts as a great conditioner for your soil. It contains a wide range of nutrients including potassium, calcium, magnesium, and sulphur together with micronutrients copper, zinc, manganese and molybdenum and finally some nutrients that are important for animal nutrition such as cobalt, selenium and sodium.

How can enhanced weathering improve soil nutrition?

Jez: This is another crucial focus for our trials. We’re exploring how spreading basalt rock can prevent ‘hidden hunger’. Hidden hunger is when crops are deficient in a nutrient but the effects of that deficiency are not yet apparent. Often when farmers see a deficiency in their crops, it’s too late to undo the damage. By adding more of whatever nutrient is deficient they may prevent more damage, but they will have already taken a hit in yield and/or quality. Ryan: Because our crushed basalt rock contains a range of nutrients that become available over time. Farmers can replace the nutrients in their soil that have been extracted which can prevent micronutrient deficiency from reducing yields, or allow plants to become more resilient to abiotic or biotic stress.  This is something else we will be exploring in trials.

How are you able to offer the crushed basalt free of charge?

Ryan: The easy answer is by selling the carbon credits created by using the basalt. Carbon credits allow an additional revenue stream to support implementing this technology, where it wouldn’t have been cost-effective in the past. Jez: This then allows us to reinvest this money in further operations to spread more basalt with the aim of capturing and removing as much carbon dioxide from the atmosphere as possible. The difference between mineral carbon credits and organic ones is not well understood. It’s something we’re all feeling out at the moment, but the only carbon credits UNDO deals in are mineral. The organic ones belong to farmers. Ultimately, Ryan and Jez will be working towards providing farmers with all the information they need to get the most out of any partnership they enter into with UNDO. The benefit for us is to get closer to achieving that 1 billion tonne carbon removal target. Read more about our agricultural partnerships here or contact Jez and Ryan. Jez Wardman UK Agronomist - Ryan Pape US Agronomist -
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