Impact of genotype, harvest time and chemical composition on the methane yield of winter rye for biogas production

Abstract

Abstract Rye ( Secale cereale L.) is an ideal crop for the agricultural biogas production in regions with less fertile and sandy soils. Maximum methane yield per hectare is the main aim of the farmer. Objectives were to establish differences by the Hohenheim Biogas Test among (1) 25 genotypes (experiment 1) and (2) three harvest dates (early heading, early and late milk ripening) and three plant fractions (ears, leaves and stems, stubbles) for four genotypes including an analysis of their nutrient composition (experiment 2). Significant ( P −1 and 840 m 3 ha -1 respectively, combined with moderate to high heritabilities (0.71–0.98). Both traits were highly correlated ( r = 0.95, P −1 . Accordingly, methane yield was reaching a mean of 4424 m 3 ha -1 and a maximum of 4812 m 3 ha -1 . No correlations between content of crude nutrients or cell-wall fractions and specific gas or methane yield were evident neither for the plant fractions nor for the whole plant. In conclusion, harvesting at late milk ripening was clearly superior in dry matter and methane yields although specific methane yield was higher at early heading. A selection for maximum dry matter yield in rye breeding should indirectly improve also methane yield.