Humus - living earth
Humus is created by the interaction of plants with soil organisms (microorganisms, fungi, insects, etc.). Root excretions, plant residues and also dead soil organisms are continuously metabolised and built up alive in the soil. The humus content of the arable soil is therefore significantly influenced by the type of cultivation. A change in cultivation also changes the humus content.
How Humus build-up works
Plants are able to absorb CO2 from the air and convert it into sugar or subsequently into organic matter (leaves, fruits, wood, roots and root excretions). Even humans, with all their knowledge and all the technology available, are not able to do this! When the plant dies and remains on the field, the organic mass is broken down and transformed again by bacteria, fungi and small organisms. Through this process, humus can be accumulated in the soil. Some of the carbon (C) it contains, is converted back to CO2 together with oxygen (O2) and escapes into the atmosphere. The humus in the soil consists of 58 % carbon. So if the humus content of the soil can be increased, the carbon it contains will be stored long term and will not escape into the atmosphere as CO2.
Humus build-up therefore means that part of the carbon that has been bound in the plant is not released again, but is converted into stable humus substances.
Humus depletion means that not only is the entire organic mass that has grown on the soil broken down again, but that in addition the humus contents in the soil are attacked and the carbon escapes into the atmosphere in the form of CO2. In recent decades, farming worldwide has been "humus-depleting" - that is, the humus reserves of arable soils have been reduced by farming practices (soil loosening, commercial fertilizers, sprays, monocultures, etc.). Compared to the 1930s, we now have only a third to a maximum of half of the original humus reserves in the soil. By changing the way arable land is managed, humus can be built up in the soil, as well as stabilized in the long term and not escape into the atmosphere as CO2.
Principles of humus build-up
The humus content of arable soils is influenced not only by the parent rock and the prevailing climate, but also to a large extent by the type of cultivation. A change in management therefore also changes the humus content. Measures that mainly help to determine the extent of humus build-up can be divided into three major principles:
Recommended practices of HUMUS+
Humus can be built up and stabilised in the soil through a change in management practices.
The aim of this project is to rehabilitate the soils and build up humus in the shortest possible time. The individual farmers are informed professionally and trained accordingly (see also HUMUS+ Knowledge).In contrast to all other "quality assurance programes", the farmer is not given any mandatory requirements as to which of the individual measures must be implemented. In other words, only recommendations are made and the success of humus build-up is measured for the individual farmer. This results in a variety of different ways in which successful humus build up can work. An appropriate evaluation tool can then be used to check and improve the recommendations for successful humus build-up.