Perennial Crops as Renewable Resource – A Good Choice Concerning Climatic Risks?

Perennial crops can be used as renewable resource but only rare information concerning their site-specific biomass production are available. Also, their yield stability as well as the quality of the produced biomass, whether for energetic or material utilisation, is relatively unknown. Perennial crops offer several ecological benefits such as protection of soil and waterbodies, long flowering and cover for wild animals during winter. Most of these crops have a high yield potential and are – after planting and establishing is completed – labour efficient to cultivate. Concerning climate change and the presumed higher risk of extreme weather conditions, perennial crops might be a good supplement to common annual crops. The aim of a Bavarian project, started 2014, is to evaluate several perennial crops at six Bavarian sites with varying soils and climatic conditions. Cup plant (Silphium perfoliatum), sida (Sida hermaphrodita), tall wheatgrass (Agropyron elongatum), switchgrass (Panicum virgatum) and miscanthus (Miscanthus x giganteus) are cultivated in field trials in 100 m2 plots and four replications. The annual crops maize and rye are similarly grown as references. Besides plant development and yield measurement, the potential methane yield and/or fuel properties will be determined to assess the quality and suitability of these crops for different usages. Trials concerning cultivation techniques and weed control complement the agricultural investigations. Ecological aspects of perennial cropping will be evaluated by measuring carbon levels in the soil as well as stocking rates of earthworms used as indicator for changes in soil biota as a result of perennial crop cultivation. Yield and quality results from foregoing trials for the various crops and first data of the now started field trials will be presented. The data and experiences will allow detailed consulting of farmers who are interested in increasing the biodiversity in their fields and minimising their climate-caused production risks.