19 January 2022

Necromass!

There’s a party trick among soil scientists. They take two clumps of soil, one healthy, one not, and submerge them in glasses of water. The bad soil immediately dissolves in to the world’s least appetising glass of squash. The good soil remains whole, separate from the water, often leaving it transparent.

The reason for this is soil structure. The bad soil is little more than clay, sand and some other stuff that happens to occupy the same space. The good soil is entwined like a tapestry. The threads of this tapestry are plant roots and fungal networks (hyphae). So far, so intuitive, but recent research suggests that half of the carbon (and these networks in the soil) are necromass. This amazingly named material is all of the dead plant and fungal matter from yesteryear, whose tunnels remain like the remains of an underground city, buried and forgotten.

Research has shown that necromass provides nutrition to living plants, structure to the soil, acts as a store of greenhouse gases and is a vital component in the carbon cycle. It constitutes half the carbon and 80% of the organic matter in healthy soil. That is a lot. If allowed, this necromass can exist for 300 years. The problem is, we so often don’t allow this. By turning over the soil we release this carbon in to the atmosphere.

This has implications for us as farmers. The popular consciousness has shifted away from the idea of trying to create a sterile environment for growing. We can’t take a living thing (the soil), kill it’s life (microbiome), then stick plants in it and expect them to grow in a happy, healthy and harmonious way. A massive weight of evidence now shows that diversity is king when it comes to healthy plants. Diversity of nutrients, diversity of plantlife, diversity of fungi and bacteria, diversity of wildlife. We spoke in a previous post about the soil being analogous to our own gut – health in this case is the presence of a diverse and vibrant bacterial paradise. So we knew that we needed to create this diversity in soil where it might otherwise have been absent (such as the land we’ve reclaimed from industrial agriculture). This means seeding, planting, grazing and pooing. But the implication of the importance of necromass is that there really are no shortcuts. We can’t just take over the land, declare it as belonging to regenerative agriculture, stick a flag in it and start growing great flowers. Land development is a long game. Though we can accelerate the soil’s recovery through intelligent intervention, we cannot circumvent it. Necromass shows us that not only do we need to restart the cycle of life in the soil, but that we need to let it run through this cycle and build up some dead matter as well as the living.

So what are the practical consequences for us? Well the good news is that the no dig practices we use as standard explicitly avoid turning over the soil. By building on top of what’s already there we preserve this soil life and even feed it from above. The requirements for our new land are slightly more egregious. Following years of heavy duty farming, pesticides, herbicides, fungicides, other -cides we’ve never heard of nor want to, the soil life in this land is a fraction of that in the land we’d previously grown on. This means we cannot plant directly in to it, but need to develop the soil and plant diversity more actively before grazing this with animals, fertilising it with their waste then finally starting to build our beds. We’ve written more on this in previous posts on our green manure seeding and our use of animals.

So, impatient as we are, we can’t rush this bit. As we take on more and more of this sort of land we’ll get better and better at cultivating a healthy soil biome, but it turns out that nature doesn’t care if we’re in a hurry, so we’ll make sure we take the time to do it right.

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