Usefulness of organic profiles for evaluating the stable organic matter fraction produced during decomposition in soil and the classification of organic manures.

The organic compositions of 61 organic manures currently used in agriculture were analysed and eight of them incubated in soil under controlled conditions. These organic analyses were compared statistically with the total C and N concentrations. The organic composition of a manure was neither correlated with its C and N contents, nor its C/N ratio. Four groups of products: fertilizers, organic manures, raw materials and products with a high mineral nutrient content, were defined according to their organic profiles and their agronomic properties and checked by principal component and factor analysis. There was a general correlation between the carbon remaining in the soil and the organic composition of the organic manures. This model provides a consistent evaluation of the stable organic matter supplied to the soil after decomposition of organic manures whose organic profils have been determined and also takes into account the influence of the mineral fraction on humification.