Maize and legumes root growth and yield as influenced by organic fertilization, under Mediterranean environmental conditions.

Field experiments were conducted to determine the effects of green manures on growth and yield of maize crop. This study also evaluated the effects of two different composts on nitrogen fixation and growth of legume crops. The experiments used a split-plot design with three replicates, three main plots (control - no treatment, compost 1 and compost 2) and three sub-plots (vetch, faba bean and pea). The legumes root growth was affected by the compost application. The highest root diameter, density and dry weight was found under organic fertilization treatments (compost 1 and 2). Nitrogen fixation was also affected by the compost application. The highest root and above-ground N % was found under compost 1 treatment. Moreover, the highest above-ground biomass was found under organic fertilization treatments (compost 1 and 2). Faba bean and vetch had higher biomass in comparison to pea, and both these species accumulated significantly more N than pea. The maize root growth was affected by the organic fertilization. The highest leaf area index, root and aboveground dry weight were found in the plots where vetch was used as a green manure. The lowest yield was found in the plots where pea was used as a green manure. The main reason for differences in maize growth between green manure treatments may be attributed to the rate of N mineralization of each green manure. The results suggest that vetch is the optimum species for use as green manure.