Sustainable bioethanol production combining biorefinery principles using combined raw materials from wheat undersown with clover-grass

To obtain the best possible net energy balance of the bioethanol production the biomass raw materials used need to be produced with limited use of non-renewable fossil fuels. Intercropping strategies are known to maximize growth and productivity by including more than one species in the crop stand, very often with legumes as one of the components. In the present study clover-grass is undersown in a traditional wheat crop. Thereby, it is possible to increase input of symbiotic fixation of atmospheric nitrogen into the cropping systems and reduce the need for fertilizer applications. Furthermore, when using such wheat and clover-grass mixtures as raw material, addition of urea and other fermentation nutrients produced from fossil fuels can be reduced in the whole ethanol manufacturing chain. Using second generation ethanol technology mixtures of relative proportions of wheat straw and clover-grass (15:85, 50:50, and 85:15) were pretreated by wet oxidation. The results showed that supplementing wheat straw with clover-grass had a positive effect on the ethanol yield in simultaneous saccharification and fermentation experiments, and the effect was more pronounced in inhibitory substrates. The highest ethanol yield (80% of theoretical) was obtained in the experiment with high fraction (85%) of clover-grass. In order to improve the sugar recovery of clover-grass, it should be separated into a green juice (containing free sugars, fructan, amino acids, vitamins and soluble minerals) for direct fermentation and a fibre pulp for pretreatment together with wheat straw. Based on the obtained results a decentralized biorefinery concept for production of biofuel is suggested emphasizing sustainability, localness, and recycling principle

Functional agrobiodiversity and agroecosystem services in sustainable wheat production. A review

Agrobiodiversity can improve the sustainability of cropping systems in a context of low external inputs and unpredictable climate change. Agrobiodiversity strategies to grow wheat are breeding ad hoc cultivars for organic and low-input systems, wheat–legume intercrops and living mulches, cultivar mixtures, and the use of genetically heterogeneous populations. However, applying those strategies can fail due the lack of a well-focused framework. Therefore, we need a better integration between breeding and management and a clear focus on crop traits related to key agroecosystem services. Here, we review the use of agrobiodiversity in wheat production, focusing on breeding and management. We discuss five agroecosystem services: (1) weed reduction, (2) nitrogen use efficiency, (3) abiotic stress tolerance, (4) disease and pest reduction and (5) yield and yield stability. We categorise agrobiodiversity into functional identity, functional composition, and functional diversity, in order to link crop traits to agroecosystem services. Linking crop traits to agroecosystem services could in turn lead to concrete options for farmers and policy. We discuss the relations between crop identity and crop heterogeneity. We also discuss the partitioning of crop heterogeneity between functional composition and functional diversity