This parameter is indicative of the initial quality of the raw materials. If we start with a high quality, we will end up with a high concentration of organic matter. The humic extract is also related to this quality, as humic acid is the result of the decomposition of the lignin mainly from the raw material. Lignin is a basic component of crop residues, husks or pruning waste (with a strong structure). Remains of fresh vegetables, sewage sludge, biodigesters, etc., will rarely give high values of humic acids.
When we see a compost, raw materials with a high degree of protein like animals (blood residues, meat, etc.) have been added to increase the value of N. The organic N is available to the plant so that it can form amino acids, enzymes and proteins that favour its nutritional balance.
It is advisable to start the composting process with a C/N ratio of 30-35. During the transformation, organic or C-containing compounds are degraded, and new substances appear, so that the final C/N ratio must be between 10 and 13. When C/N is between 10 and 13 the compost is matured, and all its components, both minerals and proteins, enzymes, etc., are readily available to the plant.
PK and macro minerals (Ca, Mg, S):
The level of P is always between 3.5 and 4, and the level of K is over 4. It could be said that this compost has an average NPK balance of 4-4-4. The other macrominerals that the compost contributes, Ca, Mg and S, are very important with very interesting levels for the plant.
Mineral variety is very important for the presence of enzymes and the nutritional balance of plants. In this case we see a high concentration of B, which is an essential micro element for flowering and for crops such as alfalfa.
By adding good compost to farming we are not only contributing minerals, as in the case of NPK, but also humic organic matter, bases such as Ca and Mg and micro minerals such as B, Zn, Mn, and others.
Therefore, it is never appropriate to compare the NPK content of a compost with that of a NPK saline fertilizer, as the compost provides very good elements for the soil and the plant, which the other does not contribute.
The chromatographic analysis of a compost requires the learning of an analysis and interpretation technique. It is one of the most useful ways to see the state of maturity of a compost over time.