Vegetation cover reduces erosion and enhances soil organic carbon in a vineyard in the central Spain

Land degradation, and soil and nutrient loss, are significant environmental problems in semi-arid agricultural environments in the Mediterranean Basin. One land use that is particularly associated with the highest rates of erosion in Spain is extensive vineyards. We examined the effectiveness of two cover crops for improving soil physical properties and reducing erosion in a vineyard located in the Henares River basin southeast of Madrid, Spain. We assessed erosion from three replicate plots of 2 m(2) each with three treatments that comprised: traditional tillage, permanent cover of Brachypodium distachyon and spring-mown crop of Secale cereale. Erosion plots under traditional tillage yielded substantially more erosion (5.88 t ha(-1) yr(-1)) than Brachypodium (0.78 t ha(-1) yr(-1)) or Secale (1.27 t ha(-1) yr(-1)). While the concentration of SOC in sediments was greater for the cover crops, the mass-corrected loss of SOC was greater under tillage (0.06 t ha(-1) yr(-1)) than under Brachypodium or Secale (0.02 t ha(-1) yr(-1)). Root biomass was two- to four-times greater under the vegetation treatments. Our measure of aggregate stability for the tillage treatment remained between 7.9 and 5.4 drops over the four years of study and values for both cover crops exceeded that for Tillage by the end of the second year. The vegetation cover treatments increased SOC by 1.2% and intrapedal SOC by 10-60% compared with Tillage. By the end of the study, steady-state infiltration in the cover treatments was 45% greater than that under tillage, with the largest increase under Brachypodium. We attribute the greater infiltration on cover treatments to a greater abundance of larger pores on vegetated compared with tilled plots. Our study reinforces the notion that there are considerable benefits of using cover crops in rainfed vineyards, not only for prevention of soil erosion, but to enhance soil condition and potentially reduce the heavy reliance on industrial fertilisers. (C) 2012 Elsevier B.V. All rights reserved.