Organic matter 

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 mineralisation. 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.

Overheating Index

The Overheating Index provides a snapshot of the silage’s susceptibility to aerobic spoilage (heating) once exposed to air. A high sensitivity allows for early preventive actions to minimise feed-out losses and maintain feed quality. It also guides management improvements for future silage production. 

Heating results from microbial activity, primarily yeasts, once oxygen is introduced (e.g., during feed-out). A temperature difference of more than 10°C between the silage and ambient air indicates spoilage.
Consequences of Heating
Heating can lead to daily losses of up to 3.5% dry matter and 15 VEM (Dutch net energy unit) per kg of dry matter. Over several days, these losses can exceed 10%. Reduced intake and even complete spoilage due to mould growth are additional risks.

Interpreting the Overheating Index
The index reflects how prone the silage is to spoilage upon exposure. Scores below 20 indicate low risk; scores above 50 indicate high risk.

Management Recommendations
- Feed more sensitive silage during winter
- Adjust feed-out rate or clamp height
- Use propionic acid on cutting faces
- Apply extra weights to improve clamp sealing

Future harvest tips
- Chop finer
- Increase compaction capacity
- Use additives (inhibitors or preservatives)

Method

Eurofins Agro analyses samples according to prescribed and established methods. The analysis report briefly describes the method. Here you can also see which method has been accredited by the Accreditation Council. We then put a Q after the method.
Below in the downloads, in the document “Laboratory protocol horticulture” (in Dutch) you will find a detailed description of the methods. This document supplements the information on the analysis report.