Maize Biomass Production, N-Use Efficiency and Potential Bioethanol Yield, Under Different Cover Cropping Managements, Nitrogen Influxes and Soil Types, in Mediterranean Climate

To evaluate the effect of cover cropping faba bean with maize, compared to maize monocrop cultivation, on yield (dry matter), nitrogen utilization efficiency (NUE) and N fertilizer recovery fraction of maize, field experiments were carried out over a period of three years. Experimental sites were located in central Greece, on a fertile, clayey soil and on a sandy soil of moderate fertility, A factorial combination of four nitrogen dressings (0, 80, 160, 240 kg ha-1) and three legume treatments (incorporated into the topsoil or harvested before the sowing of maize and mono-cropping) were tested in a split plot design in three blocks. Results showed a substantial importance of the legume cover crop for both soil types, for all studied factors. Maize total dry biomass yield fluctuated from 13.4 to 20.3 Mg ha-1 for the control plots, from 15.1 to 21.6 Mg ha-1 when faba bean was harvested and from 15.3 to 22.4 Mg ha-1 when incorporated, for clayey soil and from 12.4 to 16.9 Mg ha-1 for the control plots, from 14.9 to 19.4 Mg ha-1 when faba bean was harvested and from 14.5 to 19.6 Mg ha-1 when incorporated, for sandy soil. The NUE was estimated at 56 kg kg-1 and 55 kg kg-1 for clayey and sandy soil, respectively. The N recovery fraction was enhanced by 10-15% after faba bean cover cropping, for both soil types. Such systems should be seriously considered in future land use planning, with respect to the sustainable cultivation of maize.