Who cares about soil anyway? Actually, we all should – soil is a miracle substance. It cleans water, prevents drought and flooding, sequesters carbon and produces nutritious food.
Until about three years ago, I had very little interest in soil – it was just the dirt under my feet. Many people told me it was important, and while I sort of believed them, I didn’t think too much about it. It was only once I started investigating the health of the soil on my own family’s farm, by digging into the soil and truly looking at it over time, that I began to realise how incredible it is.
After looking at a spade full of soil a few times, it became clear that it is a living underworld that we understand very little about. It’s estimated that scientists have only identified about 10% of all life in the soil. We are learning that soils are the stomach of the earth: consuming, digesting and cycling nutrients and organisms; in the same way we have a microbiome in our stomach, the soil is the earth’s microbiome. This underworld of soil is so vast that even arable farmers are starting to say they are animal farmers, because a farmer’s main concern is to feed the billions of living animals in their soil!
These animals below are driving the nutrient cycling, and the availability and productivity of our farming systems. So how do we learn from and understand this underworld? As a starting point, everyone can go out and start digging holes and looking at their soils. In my experience, closely observing and asking questions is the best way to understand this underworld. However, that only gets you so far – I found that I started really understanding the soil by doing some simple in-field soil tests. The tests allowed me to look at the soil in an analytical way and compare from one field to the next, as well as seeing how the soil in a particular location was changing over time. Some of the key tests I used include:
Earthworms are the largest organisms in the soil food web; if they are there, you know that the soil biology is alive and kicking! But they are very seasonal, so look in spring or autumn.
If soil has good structure, water will percolate downwards, and be stored in the profile around soil aggregates. If soil has poor structure, water will sit on the surface, or worse still, run off, taking soil and nutrients with it.
The microbial community provides the glue that holds soil together. Without it, soil crumbles away to dust. These glues are insoluble in water, so the best way to tell if your structure is held together by microbial activity (and not compaction) is to submerge it in water.
Monitor diversity and bare soil
What’s the percentage of your grass cover, broadleaves, undesirables and bare soil? This all impacts the microbial community below.
The rhizosphere is where the root exudes sugars. Microbes take the sugars in exchange for nutrients, and at the same time they secrete slimes and glues which are what build a healthy soil structure. The rhizosphere is essentially a healthy soil factory. So, if your roots are white, it implies there is very little activity happening in the plant-soil interaction.
The tests are all very simple, and to make sure farmers like us really got the most from these tests, I worked with the Pasture-Fed Livestock Association to develop the Soilmentor app (currently called Sectormentor for Soils – the name changes officially in January) that makes it easy to record observations and learn as you go.
With my first set of soil tests, I created a soil health baseline. I was able to compare results from fields under different management and, for example, identify areas to plant deeper rooting cover crops to break up compaction. The magic really happened when the tests were repeated again and again at the same sample sites. I was able to see how the underworld activity was changing, as we changed our approach on a field. It’s totally possible to do the tests without any other equipment, but I used Soilmentor to track my progress and learn from my results, recording observations, photographing findings and geo-locating sample sites. You can find out more about the app and how to do each of the tests, on the Soilmentor website.
Now I had dug a few holes and began to understand what was happening in the underworld on our farm, I wanted to experiment with different approaches to regenerating soil health. A few years ago, soils advisor Niels Corfield introduced me to the Soil Health Principles and now I always keep them to hand. Originally developed in the US by the National Resource Conservation District, these simple principles are all important in building soil health and feeding the world below our feet. Every farm (or garden) is different, so encourage people to consider every action they take using these principles, optimising as many of them as possible.
Limit the disturbance of the soil (physical and chemical)
Tillage, particularly when the soil is completely inverted, is very disruptive to all soil life, dismantling fungal networks and exposing earthworms to predators. Reducing chemical inputs such as fungicides and insecticides or ruling them out completely, will nurture soil biology and biodiversity.
Keep soil covered
Bare ground is essentially starving all those animals in the underworld of any food, causing carbon to be lost into the atmosphere; it is a recipe for soil erosion and land degradation.
Living roots in the soil
Living roots exude carbon in the soil, which is taken up by microbes and helps cycle nutrients as well as build soil organic carbon.
Animals are mobile mini-biodigesters, they are an integral part of cycling nutrients and keeping the microbiome flourishing.
Diversity is important, both between crops and amongst them. The more diverse the range of living plants, the more diverse the range of living roots, the more microorganisms are nourished and active.
Since looking and learning from the soil, I feel a new sense of connection to the amazing world beneath our feet. When making management decisions, I literally picture each field on our farm above ground and below ground. The soil is where life begins and where it returns when the life cycle has ended. We can no longer pretend soil is an inert substance to be kicked around like dirt. So, in celebration of soil, go out and dig a hole and start looking. Take photos, ask questions, go back and look again six months later. It may seem difficult at first, but it’s worth it, I promise – this is the root of healthy soils, a healthy farm and a healthy planet.
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