Nitrogen Fertilization Management of Switchgrass, Miscanthus and Giant Reed: A Review

To successfully develop production systems for switchgrass (Panicum virgatum L.), miscanthus (Miscanthus spp.), and giant reed (Arundo donax L.), accurate information on effective nitrogen fertilization management on different soil types, climate and growth conditions, and for specific end uses is essential. Nitrogen is the main element, along with water, that determines biomass productivity, but at the same time, it is also the most environmentally and economically impacting agronomic factor. Variation in rhizomes, soil biota, mycorrhizae, N deposition, absorption, mobilization, and N sources renders the uniform estimation of N need very byzantine. Moreover, the majority of studies refer to environmental conditions that are insufficiently defined or subject to peculiar local conditions that can lead to controversial or inconclusive results. The literature clearly shows that (i) great deal of uncertainty surrounds this subject, (ii) clear justifications of the N fertilization dose used in the context of agronomic trials are often missing, and (iii) researchers generally rely on common sense and personal experience, rather than sound science. Therefore, the present review has the ambition to help identify common denominators and guidelines to define the optimal N supply for switchgrass, miscanthus and giant reed as a function of environmental and growing conditions. This review addresses N supply for agronomic and ecological studies focused on biomass production and on breeding nurseries and trials focused on optimal cultivar development strategies