An important strength of organic matter input is to increase the organic matter content of the soil. It also plays an important financial role and a key role in the principle of circular agriculture.
By implementing organic matter on the field, the organic carbon content of the soil increases. This has a positive effect on the water regulation in the soil: the water can infiltrate more easily and is stored by the soil, which makes it longer available for the crop in dry periods. This better water regulation can be directly linked to a higher yield.
Evolution of the carbon content depending on crop rotation, manure input, cover crops… (Soil Service of Belgium) (Dutch)
Use of organic matter is a way to keep nutrients on the farm or field, which makes the nutrient circle (more) closed.
Organic matter is more than half carbon. Researchers more often talk about soil organic carbon than soil organic matter, but these are different ways of measuring the same basic soil property.
The ratio of carbon to nitrogen in a soil impacts how well the soil functions. To stay alive, soil microbes need a carbon nitrogen ratio in 24 parts carbon to 1 part nitrogen. If the ratio is off, that lock up of both important macro and micronutrients, impact nutrient cycling and the decomposition of crop residues. What is needed for a balance C:N is a diversity of crops.