The overseeding of two cool-season legumes (Hedysarum coronarium L. and Trifolium incarnatum L.) on switchgrass (Panicum virgatum L.) mature stands increased biomass productivity

摘要

In the Mediterranean rainfed systems, perennial warmseason grasses are profitable crops for the production of herbage as forage or feedstock for bioenergy purposes During summer, when the production of coolseason crops is scarce, warmseason grasses can improve the productivity and stability of forage cropping systems In Italy, switchgrass (Panicum virgatum L) can be cultivated for herbage production or as energy crop The objective of this work was evaluating if relay intercropping with coolseason legumes could be suited to convert a mature stand of switchgrass from energy to dual, energy and forage, production, together with improving the productivity and the quality of the harvestable biomass All these things considered, a field experiment was carried out in Central Italy, on mature stands of two switchgrass varieties, Alamo and Blackwell, overseeded with two legumes: sulla (Hedysarum coronarium L) and crimson clover (Trifolium incarnatum L) The intercropping system was compared with fertilized and unfertilized pure switchgrass stands After two years of study, data showed that the intercropping increased the total above ground biomass (AGB) productivity In the second year, the increase in total AGB production for switchgrass mixtures compared with the pure stands was greater for sulla, a biennial legume, than crimson clover.