Does the use of cowpea in rotation with a vegetable crop improve soil quality and crop yield and quality? A field study in SE Spain

Abstract

Abstract Information on the effect of cowpea-based rotations in horticulture under arid and semiarid environments are scarce despite the potential for increasing soil quality and fertility. Cowpea is a suitable legume in rotated cropping systems due to its relative tolerance to drought. The main goal of this study was to assess the effect of two cowpea cultivars, Feijao frade de fio preto (FP) and Feijao frade de fio claro (FC), during three crop rotation cycles, on soil fertility, yield, crop quality and nutritional composition of subsequent broccoli crops grown using mineral and organic fertilizers while decreasing fertilization rates by 20% compared with a broccoli monocrop. A cowpea crop was seen to contribute to increasing subsequent soil available P after three crop rotations compared to monocrop, using both fertilizers type (an increase of 30% and 120% using mineral and organic fertilizers, respectively). The use of mineral fertilizers increased broccoli head diameter (13–41 %) and yields (33–80 %), while the use of organic fertilizer increased soil aggregate stability (23–36 %) and soil enzyme activities (40–110 %). The use of organic fertilizers improved broccoli crop yield with time, with similar values than those obtained from mineral fertilizers at the end of the experiment. Thus, the introduction of cowpea in rotation under Mediterranean conditions was seen to be a good strategy for crop diversification and for reducing current N fertilizer dependency.