Do cover crop species and residue management play a leading role in pepper productivity?

There is a growing interest in improving sustainability in Mediterranean vegetable cropping systems by using winter cover crops. A 2-year field experiment was carried out with the aim of assessing the effect of cover crops and their residue managements on the following pepper (Capsicum annuum L.) crop productivity. Treatments consisted of factorial combinations of cover crops [hairy vetch (Vicia villosa Roth.), oat (Avena sativa L.) and no cover], residue management systems [tilled (as green manure, GM), or mowed and placed in strips in the crop row (as dead mulch, M)]. Cover crops were sown in early September and mechanically suppressed in May about one week before pepper transplanting. The pepper was transplanted in paired rows which were placed in the middle of the mulch strips in M treatments, the same geometry was maintained in the other treatments. The pepper crop was not fertilized and mechanically weeded twice only in the inter-row space between the paired rows in order to minimize agronomical inputs. At cover crop suppression, hairy vetch showed the highest aboveground biomass and total nitrogen content (712 g m−2 of DM and 197 kg of N ha−1, respectively), while oat exerted the strongest weed reduction. The marketable pepper yield was higher in hairy vetch than oat and no cover regardless of residue management (on average 25.4, 9.9 and 12.0 t ha−1, respectively) probably due to an abundant availability of soil nitrate throughout the pepper growing season. This was confirmed by high and constant values of SPAD readings of pepper plants grown in hairy vetch. Cover crop residues placed in strips suppressed weeds more effectively than incorporated residues. A better nitrogen nutrition and weed control led to an increase in pepper productivity cultivated in vetch mulch strips. Therefore combining legume cover crops and a strip mulching technique to manage cover crop residues could contribute to effectively increasing the crop productivity and consequently the yield of the following pepper crop. This management package could be considered an important option for organic and conventional growers seeking a way to reduce the agronomical inputs in a winter cover crop–pepper sequence.