John Barnes, Fertilizer New Zealand
Pick up a handful of healthy soil and at first glance, it may look like plain dirt. Look a little closer, and you find it is alive. Billions of tiny organisms are at work every second, breaking material down, building structure and cycling nutrients.
This activity relies on a small but important slice of the soil. Only about five percent is organic matter, yet this fraction is what turns mineral particles into a productive, resilient growing medium. When organic matter is low, soil structure weakens, fertiliser performs poorly and water either runs off or drains away too fast. The five percent is made up of carbon, humates, fungi, microbes, earthworms and compost. Each one plays a different role but all work together to keep soil functioning well.
Humates are stable carbon compounds formed from the long term breakdown of plants and animals. They help soils hold nutrients such as calcium and potassium and release them gradually as plants need them. Humates also support good crumb structure which improves infiltration and root development. Carbon is the main energy source for soil life. It feeds microbes, fungi and earthworms. Plants move carbon into the soil through their roots which keeps the whole biological system running. Where carbon levels are strong you see better nutrient cycling and more natural structure. Low carbon usually signals low biological activity.
Fungi contribute to soil structure by spreading fine threads through the soil. These threads bind particles and help protect against compaction. Some fungi form relationships with plant roots that allow plants to reach more phosphorus, zinc and water. In return the plant supplies sugars. These partnerships improve plant resilience and nutrient uptake. Microbes are another essential part of the five percent. A single teaspoon of healthy soil can contain billions of them.
They break down organic material, release nitrogen and sulphur and convert minerals and fertiliser into forms plants can use. Microbes also produce natural compounds that support plant growth.
Earthworms are a reliable indicator of soil health. They mix organic material through the soil layers, create channels that improve aeration and drainage and leave behind nutrient rich castings full of beneficial microbes. Their constant movement cultivates and fertilises the soil naturally. Compost fuels the whole system. It provides a steady supply of organic material that microbes and fungi can convert into stable humus. Compost improves moisture retention, strengthens structure and increases biological diversity.
Healthy soils depend on life as much as they depend on nutrients. The organic matter fraction may be small, but it drives the whole system. When the five percent is thriving, soils become more resilient, water is stored more effectively and nutrient use efficiency lifts. Look after the living five percent and it will take care of the other ninety-five.
To add living biology to your fertiliser plan, call Fertiliser New Zealand 0800 337 869 or visit www.fertnz.co.nz
