Covering the soil is a key concept in regenerative agriculture. In this piece, I will cover four reasons why covering the soil is a good idea. The last reason is the exception that makes the rule, with a note on flexibility when working with complex systems. Let’s get into it.
1. Water retention
When the rain falls, we want to absorb as much of that rain as we possibly can. This sounds obvious. But in many paddocks, rain will run off, taking soil and nutrients with it. This generally happens when the soil has been left bare. When we cover the soil, ideally with plants and plant litter, this layer of mulch slows down the water, allowing the soil to absorb the rain instead of letting it get away. This is especially important in the summer months when rain is scarce – if you get a single, aggressive downpour in the middle of February, you want to take advantage of that downpour. Covering your soils will allow you to do that.
2. Water retention
When the sun shines, it evaporates the water that is highest in your soil profile. If the water is sitting on top, without any protection, it will be evaporated first. Covering your soil means providing a layer of protection against this evaporation. Especially moving into the drier months, bare soils will become far drier, far quicker than those soils which are protected.
Another way to think about this is lost opportunity. Your two most important resources are sunlight and rainwater, and you get them both for free. With bare soils, you are using one of these resources (sunlight) to diminish the other (water). From an economic standpoint, it makes no sense. If you could create a situation where these two help each other, for example by creating conditions for a plant to grow, you can utilise both free resources effectively.
3. Feeding the soil
Bare soil means no food for the microorganisms within your soil. Ideally, you have a thriving community of microbes beneath your feet. Without any food, those microbes simply won’t survive. Where there should be microbes creating cities and freeways to freely exchange nutrients in your soil, you have created ghost towns. These conditions create more compaction. The tunnels through the soil which should be allowing water and air to penetrate start to collapse. Like an abandoned town, left behind as the wheels of industry move on, you’ve created conditions for more nefarious forces to take hold.
4. Conditions for weeds
On a farm, we generally see weeds as something to kill. They are taking the place of a more palatable, desirable species. In regenerative agriculture, we ask why the weeds grew there in the first place. Soils generally have a huge seed bank of all sorts of different species from tree seeds to grasses to weeds – so why, in this case, did a weed grow? When your soil lacks nutrients and structure, it is the perfect environment for weeds to invade. For example, capeweed and flatweed will grow very well on bare soils. Aristotle said that nature abhors a vacuum. This goes for your soils, too. If you leave a space, a weed will take its rightful place. If you cover your soils, these weeds will give you less problems. If you help to foster a good microbial community in your soil, you can expect even less weeds to grow. Weeds are trying to fix something in the soil, but if you create a good environment, they will have no purpose, and so won’t grow.
5. Sometimes it isn’t
I live in Thorpdale, which is spud country. We don’t grow potatoes, but all our neighbours do. This conventional way of growing potatoes goes completely against the principle of covering the soil. I’m not aware of any scalable way to grow potatoes without both creating bare soil and cultivating the soil to a virtual powder. While a mass market exists for potatoes, and no scalable solution exists, the tough truth is that this principle isn’t always going to work. What’s good for the goose isn’t always good for the gander.
This is an important overlay to these regenerative agriculture principles. They are all context specific. In a grazing situation, it is easy to say that covering the soil is the best thing to do. In that context, any bare soil generally means a loss in productivity. But for a cropping situation, it’s a whole different ball game. It’s an important principle not only in agriculture, but also in life. There is always an exception to the rule. But what about that rule?