Management of nitrogen and sulfur in arable cropping systems integrating anaerobic digestion

Summary

Within the scope of sustainable agriculture and bio-circular economy, there is a growing focus on the internal recycling of nutrients from organic residues as a crop fertilizer. Whereas nitrogen (N) is the nutrient that has the largest influence on biomass production, sulfur (S) is also an essential nutrient for plant growth that has become commonly deficient in arable cropping systems. The PhD study investigated methods including anaerobic digestion (AD) to increase N and S supply and improve their utilization in arable cropping systems. In fields in which a spring barley crop (Hordeum vulgare L.) and a leguminous cover crop were established and harvested following different strategies, the PhD study quantified the N residual effect of the belowground and harvestable aboveground biomass directly re-incorporated the following year. Results were compared to the N availability of the harvestable biomass either ensiled or ensiled and anaerobically digested. Following poor S availability in the harvestable biomass, the PhD study focused also on the recycling of S products obtained from biogas desulfurization process, including the S turnover during storage in manure, the S oxidation in soil and the subsequent S plant-availability.