GIS-based analysis to assess biogas energy potential as support for manure management in Southern Italy

Anaerobic digestion can provide a valuable aid to manure management while producing renewable energy. Biogas production is highly dependent on the size and composition of livestock farms, and the availability of fresh manure can vary throughout the year, limiting reliable assessment of potential production. The aim of this study is to develop an affordable GIS-based analysis to support manure management, based on a highly detailed livestock farm database. Databases refer to the years 2013 and 2019 and report the herd consistency and the age of each class head. Kernel density (KD) was used to identify emerging hotspot areas with potentially high concentrations of nitrogen applied to the field. Three KD classification methods were compared: defined interval (DI) into 3 classes (0-170, 170-340, > 340 kg N/ha), quantile (Q) and natural break (NB). The results show that the DI and NB areas correspond to 40 % and 84 % of the total N of buffalo origin in the Campania region, with a N surplus in the hotspot areas localized in nitrate vulnerable zones of 55 and 6 % respectively. The biogas produced from 50 % of the buffalo manure in these areas generates sufficient energy to allow the removal of the N surplus.