Photo Olivier Cor

by Olivier Cor

Directeur agronomie

What if soil worked like a car engine?

1 - What is humus

Humus is a topsoil with a high moisture content and is also rich in nutrients, which comes from the gradual decomposition of organic and plant matter. It can take many different forms, depending on its state of biotransformation, and in many ways it is essential to the life of the soil and the plants, as it provides a constant supply of trace elements, nutrients and moisture to the plants.

Soil rich in humus is usually lumpy and very dark.

“In soil you can find either very recent organic matter of both animal and plant origin, or organic matter that is more than 7000 years old!”, points out Olivier Cor, the agricultural manager at Lallemand Plant Care.

“The quality of the hummus and how quickly it is obtained will depend greatly on how the soil is worked, its composition, the climate, the environment or even the plant cover, which has a major influence on the nature of the organic material present in the soil”, he adds. For example, an initial composition of organic matter rich in nitrogen will improve decomposition, while the presence of acidic matter will make it more difficult.

This conversion (or mineralization) of “fresh” organic matter into humus, black, is known as “the humification chain”.

2 - What is humification?

Humification is essentially a reorganization of organic debris due to the activities of microorganisms: beginning with fungi, which break up the solid carbon chains, followed by the actions of bacteria. Once the organic matter has fully decomposed, we end up with a refined humus mostly made up of black or gray humic acids and fulvic acids, molecules rich in carbon.

The microorganisms involved in this process are therefore highly important, having a significant impact on the dynamic and speed of the decomposition of carbon in soil.

From a biochemical perspective, “everything revolves around the carbon cycle mobilized by the plant, which decomposes carbon then reintegrates it. In soil, carbon is the essential element that, just like a carburetor in a car, will make the engine run well, or not, as the case may be!”

“All these little organisms will make this carbon engine ‘run’, some faster than others, with the organic matter acting as the gas tank”. Managing organic matter therefore comes down to managing the life and richness of soil. If you don’t give it enough food precisely when it needs it, the engine will stall!

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Stay in the loop - part 2