This paper describes the complete findings of the EU-funded research project OPTIMISC, which investigated methods to optimize the production and use of miscanthus biomass. Miscanthus bioenergy and bioproduct chains were investigated by trialing 15 diverse germplasm types in a range of climatic and soil environments across central Europe, Ukraine, Russia, and China. The abiotic stress tolerances of a wider panel of 100 germplasm types to drought, salinity, and low temperatures were measured in the laboratory and a field trial in Belgium. A small selection of germplasm types was evaluated for performance in grasslands on marginal sites in Germany and the UK. The growth traits underlying biomass yield and quality were measured to improve regional estimates of feedstock availability. Several potential high-value bioproducts were identified. The combined results provide recommendations to policymakers, growers and industry. The major technical advances in miscanthus production achieved by OPTIMISC include: (1) demonstration that novel hybrids can out-yield the standard commercially grown genotype Miscanthus x giganteus; (2) characterization of the interactions of physiological growth responses with environmental variation within and between sites; (3) quantification of biomass-quality-relevant traits; (4) abiotic stress tolerances of miscanthus genotypes; (5) selections suitable for production on marginal land; (6) field establishment methods for seeds using plugs; (7) evaluation of harvesting methods; and (8) quantification of energy used in densification (pellet) technologies with a range of hybrids with differences in stem wall properties. End-user needs were addressed by demonstrating the potential of optimizing miscanthus biomass composition for the production of ethanol and biogas as well as for combustion. The costs and life-cycle assessment of seven miscanthus-based value chains, including small- and large-scale heat and power, ethanol, biogas, and insulation material production, revealed GHG-emission- and fossil-energy-saving potentials of up to 30.6 t CO2eq C ha−1y−1 and 429 GJ ha−1y−1, respectively. Transport distance was identified as an important cost factor. Negative carbon mitigation costs of –78€ t−1 CO2eq C were recorded for local biomass use. The OPTIMISC results demonstrate the potential of miscanthus as a crop for marginal sites and provide information and technologies for the commercial implementation of miscanthus-based value chains.

No abstract

No abstract

No abstract

Maize (Zea mays L.) is Mexico's primary staple food, but the Country's degrading soils and climate variability limit its productivity. Conservation agriculture (CA), a management technique that combines minimal tillage, permanent soil cover, and crop diversification, could reduce soil degradation and help improve soil health. There is however a lack of information about the effects of CA on soil health in the diverse agroecological conditions in Mexico. This study reports results of a field trial network established to adapt CA to Mexico's diverse cropping systems and local conditions.Physicochemical soil health, also referred to as soil quality, was studied in 20 trials in agro-ecologies ranging from handplanted traditional systems to intensive irrigated systems, initiated between 1991 and 2016. Soil in CA was compared to the local conventional practice (CP), which commonly involves tillage, residue removal, and continuous maize production. Across the sites, organic matter and nitrates were higher in the top (0-5 cm) layer of soil and soil aggregate stability was greater under CA than under CPs. For other soil health parameters, such as nutrient content, pH or penetration resistance, the effects of management varied widely across sites and soil types

Conservation agriculture, characterized by minimal tillage, permanent soil cover and crop diversification, has been widely adapted under rainfed conditions, but adoption under irrigated conditions is limited. An experiment initiated in 1997 to evaluate the level of tillage and the amount of soil cover needed for conservation agriculture to work under irrigated conditions in the highlands of San Luis Potosí, Mexico. The trial encompassed seven treatments: conventional tillage, two types of reduced tillage and permanent raised beds (PB), which are untilled, with four levels of soil cover in an irrigated rotation with maize (Zea mays L.) in the summer and fodder oats (Avena sativa L.) in the winter. Maize and oats yielded significantly more under PB than with tillage. Maize yielded on average 1.2 Mg ha−1 more in PB with the hybrid used from 1997 to 2008 and 3.9 Mg ha−1 more with the hybrid used from 2012 to 2017. Permanent raised beds generated on average $18,424 MXN ha−1 more profit than the tilled treatments and increased soil organic carbon on average 63% at 0 to 5 cm depth and 32% at 5 to 30 cm depth. The trial shows that conservation agriculture, with PB and little residue cover, is a viable and sustainable option in similar production systems.

A long growing season, mediated by the ability to grow at low temperatures early in the season, can result in higher yields in biomass of crop Miscanthus. In this paper, the chilling tolerance of two highly productive Miscanthus genotypes, the widely planted Miscanthus x giganteus and the Miscanthus sinensis genotype 'Goliath', was studied. Measurements in the field as well as under controlled conditions were combined with the main purpose to create basic comparison tools in order to investigate chilling tolerance in Miscanthus in relation to its field performance. Under field conditions, M. x giganteus was higher yielding and had a faster growth rate early in the growing season. Correspondingly, M. x giganteus displayed a less drastic reduction of the leaf elongation rate and of net photosynthesis under continuous chilling stress conditions in the growth chamber. This was accompanied by higher photochemical quenching and lower nonphotochemical quenching in M. x giganteus than that in M. sinensis 'Goliath' when exposed to chilling temperatures. No evidence of impaired stomatal conductance or increased use of alternative electron sinks was observed under chilling stress. Soluble sugar content markedly increased in both genotypes when grown at 12A degrees C compared to 20A degrees C. The concentration of raffinose showed the largest relative increase at 12A degrees C, possibly serving as a protection against chilling stress. Overall, both genotypes showed high chilling tolerance for C-4 plants, but M. x giganteus performed better than M. sinensis 'Goliath'. This was not due to its capacity to resume growth earlier in the season but rather due to a higher growth rate and higher photosynthetic efficiency at low temperatures

Weed management is one of the main challenges of conservation agriculture. Although all three components of conservation agriculture (minimal tillage, permanent soil cover and crop diversification) can reduce weed populations, these effects may only become apparent in the medium to long term. This study evaluated weed biomass, density and diversity with and without herbicide control in a long-term trial initiated in 1991 in the Mexican Highlands to evaluate all three components of conservation agriculture. Data were collected in 2004, 2005, 2013, 2014 and 2015. Weed density and biomass were generally lower in conservation agriculture than with conventional tillage. The three components of conservation agriculture significantly reduced weed biomass, which was lower when all three components were applied together. When herbicides were applied, weed biomass in conservation agriculture was 91% lower in maize and 81% lower in wheat than in conventional tillage. Different treatments favored different weed species, but no trend toward increased perennial weeds was observed in conservation agriculture. These data supported claims stating that if adequate weed control is achieved in the initial years, weed populations in conservation agriculture systems are lower than in conventional tillage systems.