Tillage effects on yield and nitrogen fixation of legumes in Mediterranean conditions

The no tillage (NT) technique represents a valuable alternative to conventional tillage (CT) for many crops, but little research has evaluated the effects of its use on the performance of grain legumes, particularly in Mediterranean regions. The present study assessed the effects of NT compared with CT on the grain yield and N2 fixation of chickpea (Cicer arietinum L.), faba bean (Vicia faba L. var. minor), pea (Pisum sativum L.), and lentil (Lens culinaris Medik.). The experiment was carried out under rainfed conditions during four growing seasons. Nitrogen fixation was estimated using the 15N isotope dilution technique. The response of the four species to the tillage system varied significantly by year. The grain yield was significantly higher under NT than under CT only for pea and chickpea, but the differences between the two tillage techniques were consistent only when rainfall was very scarce. The percentage of N fixed differed by species in the order faba bean > chickpea > pea > lentil. The effects of tillage on the N2 fixation process varied significantly by species and year. Nitrogen balance was positive for faba bean and lentil and negative for chickpea and pea, with no differences by tillage. The results indicate that in cereal-dominated Mediterranean agro-ecosystems, NT can be a valuable option for producing grain legumes, as it can improve productivity, particularly under conditions of deficient soil moisture.