Effect of organic and mineral fertilization on faba bean (Vicia faba L.)

The aim of this research was to evaluate the effect of various combinations of organic and/or mineral fertilizers on faba bean (Vicia faba L.) to identify the best treatment for balancing yield, seed quality and composition and soil fertility maintenance over time. Wet olive pomace, an olive-mill by-product very abundant in olive oil producing countries, was used for fertilization trials. The use of wet olive pomace at 140 Mg ha−1, combined with half of the conventional N, P, and K dose of mineral fertilization, allowed to achieve the same faba bean productivity of full mineral fertilization. Higher levels of wet olive pomace did not induce further productivity increase. The highest protein content in dry faba bean seeds (276.05 g kg−1) was detected at full mineral fertilization. Phenolic compounds and antioxidant activity showed an opposite trend and tended to be lower in case of full mineral fertilization alone, whereas were higher in unfertilized control and in the trials fertilized with combinations of half mineral fertilization and olive pomace. The latter fertilizing condition also allowed to suppress the infesting flora. The use of wet olive pomace for agricultural purposes could therefore represent an environmentally friendly support to mineral fertilization, adding value to a by-product.