ASSESSING AGRONOMICAL PERFORMANCES OF DIGESTED LIVESTOCK MANURE TO FRONT NITRATE LEACHING IN SOIL

摘要

Anaerobic digestion of livestock manure is one of the most promising approach for producing biogas,because of it allows also to reuse the obtained solid fraction of biodigestate in agriculture as soil amendment, beingthis organic biomass rich in nitrogen. Effectively, the direct application to soil of animal manure can go in conflictwith the Directive 91/676/CEE on the “water protection from nitrates”, especially in vulnerable zones, such as thoseof Northern Italy. The objective of our study was to evaluate the agronomical performances of the solid fraction ofpig livestock manure, previously digested under anaerobic conditions or not-digested, as soil amendments, taking intoaccount the influence of biodigestion process onto the organic biomass in relation to nitrogen availability andfollowing plant uptake.The greenhouse experiment was conducted on Lactuca sativa L. The production and the quality of lettuce wasevaluated in relation to digested and not-digested pig livestock manure application. Obtained results indicated that theorganic matter from digested livestock solid fraction was better stabilized respect to the not-digested one, thusconfirming the increased amendment properties of the digested material. A strong effect on yield, mainly due to thesoil chemical-physical characteristics and fertility, was noticed. The biomass production and quality parametersrelated to lettuce showed that the digested livestock manure gave results close to those obtained by applying commonurea fertilizer; moreover, when the digested pig manure was used as nitrogen source, a net decrease in nitrate uptakeby lettuce leaves was recorded.