Microbes in Soil Feed Your Plants

Microbes in Soil Feed Your Plants

In nature, leaves fall to the ground, animals defecate where they want and animal carcasses decompose into the soil. Organic (animal and plant) remains perish, serving as food for plants and trees. Nature knows no waste. In the forest, trees never need to be fertilized or watered. The forest feeds on itself. Organically.

When it comes to plant cultivation, however, there are some major differences. First of all, humans determine which plants are desired for cultivation. Other plants are considered "weeds". This choice is not always the most logical in a specific place under the given conditions. In many cases, nature would choose a different plant.

A second major difference when it comes to cultivation of plants is that the plant (or fruit) is removed during harvest. In the forest the plant would become food for other plants after its death, but in cultivation conditions the soil is no longer fed with dead plant material. Thus the soil is depleted and its reserve nutrients are quickly exhausted.


A cultivator basically has two options to feed new generations of plants. The first option is feeding plant roots with synthetically manufactured nourishment. NPK, it says in big letters on the packaging of fertilisers. The cultivator feeds the roots directly with easily absorbed nitrogen (N), phosphorus (P) and potassium (K). These are a real treat for plant roots. They no longer need to do their best to get nourishment. This means that the roots do not develop well. After all, good roots are unnecessary when there is a constant drip of easily absorbable nutrients from above. This means that plants become lazy and idle. They don’t get any workout. These plants are vulnerable and have little resistance. If there is a pathogenic bacterium or fungus in the area, the plants are quick to get sick. The cultivator then fights that pathogen with pesticide.


The other option is more natural. The biomass removed during harvest is replenished. In the forest, organic 'waste' is bio-degraded by earthworms, insects, protozoa, nematodes, fungi and bacteria. A part of the organic waste in the forest therefore finds its way into the ‘stomachs’ and bodies of microbes and insects. Underground the insects eat microbes and the microbes each other. In this process of eating and being eaten, fecal matter and other substances are produced. The fecal matter is valuable plant food, full of ammonium, nitrate, phosphorus and many other nutrients.

Earthworm fecal matter is considered fertile manure. An earthworm eats his daily body weight, and excretes most of it again. The earthworms under a field or forest area the size of a football field would produce about 2,000 kilograms of fertile manure daily. Free of charge!

Fungi break down woody materials that are hard to digest, but also break down rocky bits of soil using enzymes. They dissolve minerals in compounds, making them absorbable for plant roots. The same is true of soil bacteria, although they prefers organic materials which are easier to break down. Bacteria are the favorite food of protozoa, single-cell organisms in the soil. And protozoa are an item on the menu of the nematodes. Healthy soil is a lively circus!

As mentioned, the system of soil 'produces' the nutrients plants need. But the soil needs a constant input of organic matter. In the forest this is readily available. Above ground, this comes in the form of fallen leaves and other organic material. Underneath it, in the form of humus, organic matter. Humus is the part of organic material which is tougher to break down. It consists of organic material that has not fully decomposed. Actually it can be considered a kind of ‘semi-finished’ food for the soil. Humus acts as a larder for the plant. Fungi and bacteria better at breaking down hard-to-digest material feed on humus, which means it provides a kind of 'slow food' to a certain part of the soil system. It is broken down slowly. In turn, a large number of other microbes feed along with the diligent humus-crushers. And the plant roots are all too happy about the released nutrients...

Training Increases Strength

The natural way of feeding a plant is less direct than synthetic fertilisers. Plants have to do their best to get the food offered by the soil. That produces 'well-trained' root systems that can take a beating. What’s more, fungi and bacteria also produce antibiotics and vitamins, protecting plants naturally against pathogens. This slow, cumbersome, organic way of feeding produces healthy, strong and resilient plants.

Soil Life

Soil life, the collective name for fungi, bacteria, protozoa, nematodes, insects and earthworms, is a community in itself. A rich and varied soil provides plants with everything they need to survive. The plants attract many microbes in the few millimeters around their roots by secreting sugar, an important basic foodstuff for the microbes. This means that in the area around the roots of plants, the so-called 'rhizosphere', there could be up to a hundred times as many organisms as elsewhere in the soil. The combination of plants fueled by microbes, and soil which in turn feeds the plant, is called the soil food web.

Symbiosis, Stronger Together

Symbiosis is a cooperative relationship between two or three bodies, where all the bodies profit. An important symbiosis for plants is the ‘Mycorrhiza’, a collaboration between certain fungi and plant roots. The roots give the Mycorrhiza fungi sugars, and in return the fungi transport nutrients to the plant via their extensive network of hyphae, including phosphorus, which is difficult to extract from the soil. The fungus does so in a special way. The hyphae bore into the plant roots, but the roots then digest the hyphae, which are packed with nutrients. Through cooperation with Mycorrhizal fungi, the surface area of ??the root system of plants is increased up to tenfold. Mycorrhiza is very important to many plant species.

Humus, the Buffer

A little more information on humus. Humus feeds the soil. The humus layer provides many soil organisms with an ideal place to live. In addition, humus is a water buffer. It acts like a sponge. When it rains, humus absorbs a lot of rainwater, and then releases it slowly, so that plant roots also have moisture in dry times. Humus also plays an important role in the regulation of the pH-levels in the soil.

Compost, the Tool of the Bio-Cultivator

Compost is the cultivator’s answer to compensating the soil for the organic material he takes away by harvesting. The harvest interrupts a cycle, which is 'restored' with compost, one might say.

Compost is bio-degraded animal and vegetable waste. Garden waste, kitchen waste and other natural waste is bio-degraded on compost heaps or in special compost systems to a coffee-brown 'loose' substance that smells like fresh earth. Bio-cultivators replenish the organic material removed by harvesting plants with a layer of compost. Thus they ensure that the soil remains well-nourished. If necessary, they add extra soil bacteria and fungi or other soil organisms. The more varied the underground life in the garden, the better the plants grow. Soil organisms convert the compost further into humus, and feed on a portion of the organic material before providing food to plants when they themselves are eaten and excreted again. In this way, the compost restores the balance disturbed by harvesting. Using compost creates a situation rather similar to the natural conditions in the forest.

Pesticides, a Downward Spiral

There is little need for pesticides in an organic farming environment. Plants are stronger and have a lot of resistance, usually warding off an attack of pathogens by themselves, without poison. In fact, toxic pesticides are bad for the soil. Earthworms, bacteria, fungi and other organisms disappear in areas where pesticides are used. Sometimes, ‘natural substances’ can be added in the case of undesirable insects and diseases, but this seldom be necessary.

Nature has been around longer than mankind. Plants were growing for eons before humans even walked upright. Nature has more experience in the functioning of plants than mankind will ever acquire. Plant cultivation is to intervene in nature. However, by following natural principles, a breeder can stay close as possible to the proven natural cycles. In this way, a yield that is naturally free of toxins can be delivered, and the disturbance of the natural balance is minimized.

Authors: Charles Schelfhout & MIG