Benefits and weaknesses

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.

Use of organic matter is a way to keep nutrients on the farm or field, which makes the nutrient circle (more) closed.

• Use of farmyard manure keeps a high quality product (when it comes to nutrients as well as organic matter) on farm. 
• Harvest residues can be removed from the field. Leaving them at field, on the soil or incorporated, they are a good source of nutrients and organic matter.
• Cover crops can be used as catch crops. After harvest of the main crop there are still nutrients available in the soil. Without a crop to take up the nutrients, they leach to ground or surface water. The catch crop takes up these nutrients. After winter the catch crop is incorporated. In this way the nutrients stay in the top layer of the soil and are available for the following crop.
• When compost is produced on farm, it’s made from materials rich in organic matter and nutrients, that otherwise would be disposed from the farm. 
• Woodchips are produced when managing hedges and/or trees. Use of woodchips at field, closes this the nutrient and organic matter circle.  

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.