Organic matter consists mainly of plant residues and partly of animal residues/excretion of, for example, soil life. The amount of organic matter in the soil affects, among other things, the workability, structure and moisture retention capacity of the soil. Organic matter also retains plant nutrients and can make these available to the crop during the growing season. An important factor here is nitrogen; in soils with a high organic matter content, a lot of nitrogen can also become available through mineralization. Generally speaking, the lower the organic matter level, the lower the nitrogen release. The organic matter content is thus important for a whole range of soil properties. It is therefore important to monitor the development of the organic matter content in the soil. The decomposition of organic matter in the soil depends on many things:
- Type of soil (on dune sand, the percentage degradation is six times higher than on acidic peaty soil)
- Moisture balance of the soil (if drainage is poor, less decomposition occurs)
- High manure application in the past (young organic matter breaks down quickly).
In terms of advice, organic matter plays a role in liming and calculating the K number.
Why do we measure organic matter quality?