Stubble Management Effects On Barley and Vetch Yield After Zero Tillage In Mediterranean Climate.

In summer-rainfall areas, crop residue cover is a major component of conservation agriculture, as stubble retention can protect the soil, increase rain infiltration, lower evaporative loss, and give higher yield. Since relatively little research has been conducted on effects of stubble retention on winter crops in areas having no summer rainfall, this study examined the effects of crop residue on crop performance in a cool Mediterranean area. The two rainfed experiments were conducted on barley stubble in central Bekaa Valley, Lebanon in RCB designs with 4 treatments and 4 replicates. Barley (Hordeum vulgare L.) and narbon vetch (Vicia narbonensis L.) was sown with a no-till drill in 2009-2010 and 2010-2011, respectively. In 2009-2010, the heavy simulated grazing treatment (all stubble cut and removed) led to the best seedling stand and early growth vigor, earliest heading and maturity, tallest plant, and highest harvest index and grain yield (1930 kg/ha), which was similar to the control (leaving stubble intact) and the 2x stubble treatment (control with added stubble from simulated grazing), but was higher than the 3x stubble treatment (control with 2 times the amount of stubble added) (340 kg/ha). In 2010-11, heavy simulated grazing gave the best seedling stand and early growth vigor, which were similar to the light simulated grazing (only standing stubbles removed) and the control, but were better than the 2x stubble treatment. The control yielded the highest amount of grain (3210 kg/ha) and straw (4700 kg/ha), which were similar to the light and heavy grazing, but were higher than the 2x stubble treatment (2260 kg/ha grain and 3200 kg/ha straw). This study shows that non-excessive cereal stubble retention under a cool Mediterranean climate may not affect seedling emergence and growth, as well as grain and straw yields of winter crops.