Short term effects of bioenergy by-products on soil C and N mineralization and biochemical properties

Bioenergy by-products largely vary in their composition and properties and they can impact soil fertility in different and unpredictable ways. We studied the effects of the application rate of bioenergy residues with contrasting properties on C and N mineralization, element availability and biochemical properties. Results underlined that the process from which the by-products originated had a great effect in determining the agronomical properties of the residues. In particular, sorghum whole stillage from bioethanol production increased biological fertility, but caused N immobilization, manure whole stillage from bioethanol production greatly increased P availability, while manure anaerobic digestate supplied significant amounts of N. A direct relationship was found between rate of application of byproducts and N and P availability. Our study indicated that the reliability of the agronomical utilization of bioenergy by-products requires a thorough evaluation of their impact on soil fertility