Specific Biogas Yield of Maize Can Be Predicted by the Interaction of Four Biochemical Constituents

Abstract

The expansion of biogas production in Germany has raised the question regarding a biogas maize ideotype. The aims of the present study therefore were to estimate the potential specific biogas yield (SBY) of maize from its composition and to derive recommendations for biogas maize breeding. The work was based on a 2-year, multisite field experiment which provided large genetic variations in maize forage quality. SBY was determined via a batch test. A significant interaction between site and fermentation inoculum in the first experimental year required optimization of the batch test procedure before determining the SBY of second year samples to avoid any systematic effects from the measurement method. Correlation analysis revealed significant positive effects of starch, crude fat, enzyme-soluble organic matter, and metabolizable energy on SBY. A negative correlation was found for acid detergent lignin. Since, however, SBY was not clearly determined by a single parameter, a multiple linear regression (MLR) on SBY was conducted. The results of MLR revealed that the contributing biochemical constituents were crude fat, hemicelluloses, acid detergent lignin, and water-soluble carbohydrates, with the first two characters being positively correlated with SBY and the last two showing a negative relationship to SBY. It is concluded that a biogas maize ideotype can be derived, which differs distinctly from that for ruminant nutrition and which can be achieved in different ways through the combination of various biochemical constituents. For farmers and operators of biogas plants, the regression model provides the opportunity to better characterize their substrates and to perform quality-oriented accounting.