Agronomic quality of digestates in Normandy - december 2021

In order to provide answers to various questions regarding methanization digestates (possible source of pollution, composition, spreading practices, possible loss of soil organic matter, and so on), this report defines digestates and discusses their properties (agronomic properties such as fertilising and amending values). It reports results of a survey of the agronomic quality of digestates in Normandy by presenting the sample (number of surveyed units, unit types, digestate type, methanizer supply, constructors, number of digesters, digestion volume, digestion temperature, length of stay in the digester), spreading methods and practices (valorisation by spreading or marketing, spreadable surfaces, receiving crops, type of the spread digestate, spreading periods, returns on experience on spreading and odours, fertiliser saving, and so on), and the digestate agronomic quality (annual quantity, phase separation type, recirculation of the liquid phase, post-treatment, storage cover) with analysis results (number, period, frequency of analysis, sampling location, results for various contents). It discusses the mineralisation of carbon and nitrogen. It formulates recommendations for a digestate use in agriculture (regulatory context, spreading rules, recommendations regarding nitrogen volatilisation, doses and inputs)