Alternative crop rotations under Mediterranean no-tillage conditions: Biomass, grain yield, and water-use efficiency

Abstract

In Mediterranean semiarid areas, barley (Hordeum vulgare L.) and wheat (Triticum aestivum L.) are major crops because they are well adapted to limited-water environments. In this study we tested the performance of alternative rotations to the typical barley and wheat monocultures in a rainfed Mediterranean semiarid area of northeastern Spain under a no-tillage (NT) system. Four rotations were established and maintained over 6-yr period (1999-2000 to 2004-2005): a wheat monoculture (W-W-W), a barley monoculture (B-B-B), a wheat-barley-rapeseed (Brassica napus L.) rotation (W-B-R), and a wheat-barley-vetch (Vicia sativa L.) rotation (W-B-V). Aboveground biomass, grain yield, water use (WU), and water use effi ciency (WUE) were measured several times every season during the study period. All the parameters studied had a strong dependence on the rainfall variability found between growing seasons. Barley under rotation performed better than barley under monoculture in yield and WUE terms. However, wheat performed as well in a monoculture production system as it did in rotation. Rapeseed and vetch failed the 80 and 35% of the growing seasons, respectively. However, in semiarid Mediterranean agroecosystems of northeastern Spain, despite the benefi cial rotation eff ect of theses alternative crops on barley performance, economical benefi t of the overall rotation is doubtful since vetch failed in 2 out of 6 yr and rapeseed failed 5 out of 6 yr.