TECHNICAL
Ninety-five percent of the food we eat comes from the soil
Don’t treat your soils like dirt I remember a poster at a soils conference I attended a number of years ago that stated, ‘Stop Treating Soils Like Dirt’. It was a catchy phrase and a play on words but the message was incredibly important as humans have been responsible for the degrading of soils for thousands of years. Robin Boom : CPAg, Member of the Institute of Professional Soil Scientists This has resulted in topsoil loss and desertification, with vast swaths of once productive land in the world now being virtually useless. Fortunately in New Zealand, most of our productive land has only been used for growing food for a couple of hundred years at the most, so the amount of degradation is significantly less than in much of Europe, Asia, North America, Africa and the Middle East. The European Commission has come out with a Mission Area: Soil, Health and Food. It states “Healthy soils are essential for our life and that of future generations. Soils form the skin of the earth and are fundamental for all life-sustaining processes on our planet. A mission in the area of soil health and food will mobilise resources and people (e.g. researchers, land managers, public authorities, 56
The ORCHARDIST : JULY 2022
businesses and citizens) to engage in activities for soil restoration, as this is the basis for healthy people and a healthy planet.” The physical components of soil are air, organic matter, minerals and water, so having these in the right ratios is important for determining a healthy soil, the life-sustaining skin of the earth. In rough figures, water and air should each make up approximately 25 percent of the volume of a good productive soil, organic matter 5–10 percent and mineral matter 40–45 percent. Breaking down the mineral matter into components, an ideal loamy soil for growing plants would comprise 40 percent sand, 40 percent silt and 20 percent clay.
