What’s underfoot is important in climate change fight

Carbon. It gets talked about a lot, but many people don’t understand why it is important in the context of our food.

I’m going to cut straight to a very simple concept for all to remember: Too much carbon above the ground – in the atmosphere – is not good (look up greenhouse gases). Carbon below the ground – in the soil – is good (look up carbon sequestration).

The two are directly linked. More carbon sequestered or stored in the ground means less carbon in the atmosphere. Carbon is constantly being moved between the atmosphere and the ground, and living, breathing plants are the connection between the two forms, via photosynthesis.

Any good farmer will know that the core value of their farm is underfoot. Their most important entity is, literally, their dirt. At the end of the day, it doesn’t matter whether we are farming animals, crops or vegetables, we need to ensure our dirt is healthy, and thriving with “underground livestock” – the billions of microbes in our soil.

Where does carbon come into this? Well, the more carbon you have in your soil (in the form of organic matter), the healthier and more resilient your land, and more diverse and thriving your underground livestock.

Carbon as organic matter in your soil stores a lot of water, increases nutrient storage and exchange, and buffers the effect of toxins. So, the more nutrient-dense food you will be able to grow, the more resilient your land will be to drought and other climate change patterns, the less input (natural and synthetic) you will require, the more sustainable your operation will be, and the less impact on the environment it will have.

New Zealand soils have moderately high carbon stocks by global standards. This is thought to be due to having a lot of land under pasture, our temperate climate, some allophanic soils that hold a lot of carbon, but also – importantly – because of our relatively short history of intensive farming (of cropping and livestock) and therefore cultivation of our soils.

Cultivation is the mechanical process of preparing the soil for planting. The soil is tilled using various methods, such as ploughing, to remove weeds, aerate and prep the seed bed.

Unfortunately, repeated heavy tilling loses soil carbon, which is lost to the atmosphere, and destroys soil microbes.

“Digging is the most harmful thing we can do” says Simon Osborne, one of New Zealand’s leading regenerative crop farmers, who we also work with.

“This is because when we uplift and open up the soil, it lets in oxygen, which increases microbial oxidation (respiration) releasing carbon dioxide and nutrients,” Osborne says. So, effectively, it releases masses of carbon from the ground, into the air. On top of that, it severely disrupts the ecology of microbial/fungal networks, which are essential to holding and stabilising soil.

Any observant home gardener will have noticed the change in their soil – dry, crumbly soil with fewer microbes – in their garden beds if it has been upturned and left bare.

Going forward, if we are not careful to manage our land in a way that cyclically regenerates the soil, it’s not rocket science to imagine we will find ourselves in a pickle with soils depleted of carbon, microbes and nutrients, similar to what is found in countries such as the United States, with a much longer history of intensive cultivation.

Nicole Masters, a soil and regenerative farming specialist and author of For the Love of Soil, says that (in relation to countries such as the US and the United Kingdom) “in the past 40 years, we have lost nearly a third of arable (cropping) land to degradation and erosion, and we may have as little as 60 harvests left before catastrophic collapse”.

This is an important concept to be mindful of in the possible move towards using more land for crops and horticulture, and fewer pastures for animal grazing, in a shift towards more plant-based farming.

Dr Mike Beare, principal scientist at Plant & Food Research, notes “a change from pasture to cropping might decrease methane and nitrous oxide emissions (which are more involved with animal farming), but may have reductions in soil carbon”.

The goal will be to have systems that could benefit both: a reduction in livestock emissions and increase in soil carbon. So, in the future, all of us farmers and growers must seriously work towards a goal of increasing our soil carbon.

Osborne puts it well. “If you focus on storing more carbon in your soil, you will get paid anyway – paid in terms of your farm’s health and having to use less inputs”.

One day, the value of farmland will be significantly measured by the value of its carbon stocks.

Elon Musk recently announced a NZ$139 million grant for the smartest carbon-capturing technology idea, but I’m not sure if we can do this smarter than living plants and trees can. They’ve mastered this over billions of years.

I agree with Osborne when he says, “we have all the tools available already, where tech is and has been helpful, it’s unlocking the understanding of how it [nature] works”.

Every shrub in a hedgerow, tree in a shelter belt, flax bush by a pond, even every blade of grass helps to sequester carbon through photosynthesis. The largest carbon sink is under our feet.

I see a future where businesses will one day be penalised for emitting greenhouse gases, as the trading of carbon looks set to happen. In that case it is only fair that we must also award credit for the carbon that’s being stored safely across millions of hectares every day, all over New Zealand, by our farmers, horticulturalists, orchardists, and viticulturists. Currently, it is not counted in carbon accreditation.

Half of our own farm is based on cropping grains, seeds and legumes, and the other half is sheep. As a biodiverse, regenerative farm, we’ve been exploring how to combine the two types of farming to have a synergistic effect.

We’ve been trialling multispecies cover crops that we drill (without tillage) into the barley stubble after harvest. This is a wonderful way to ensure there’s always living roots in the ground, and with the right choice of seeds/rotation, effectively gives us two bites of income off a single paddock, with cereal production over the summer months and livestock finishing and grazing over the winter.

Combined, the two types of farming operations can be rather sympathetic to each other. The sheep “clean up” paddocks after harvest, the lost grain that the combine harvester misses is a treat for our sheep (and the many hundred paradise ducks that are providing free phosphate through their poo) while the sheep poo in the paddock over the winter helps to naturally boost soil fertility.

Meanwhile, the chicory, red/white/crimson clover and plantain mixes that are sown into stubble fields provide a wonderful clean area for our lambs to feed on.

Carbon sequestration may well hold the keys to the future of food production, and I’m confident that if we concentrate our energy on continuous soil improvement this will naturally be pulled into focus.