Brachypodium hybridum Plant Cover Improves Water Infiltration in Mediterranean Crop Soils

Crop plant cover may be an appropriate solution to avoid soil losses by erosion under Mediterranean climate, where traditional tillage aims to improve rainfall water infiltration, and direct evaporation from bare soil is avoided because plant water transpiration is a major limiting factor for non-irrigated crop productivity. Twelve crop lines of the three Brachypodium distachyon complex species with different chromosome number (B. distachyon, 2n=10; B. stacei, 2n=20; and B. hybridum, 2n=30) were grown in a field trial to assess water infiltrability and hydraulic conductivity across crop topsoils considering two different plant cover densities (low cover = 150 plants/m2; regular cover = 450 plants/m2), and in a control no-tillage bare soil. Results showed that superficial hydraulic conductivity was significantly higher in Brachypodium-covered soils with regular plant density (3.254 ± 0.710 cm.h-1) than in the no-tillage bare soil (1.965 ± 0.711 cm.h-1). On an extreme ranking basis, yields were 1.89 < k(h0) cm/h < 27.12 under covered soils, and 0.679< k(h0) < 4.330 in the no-tillage bare soil. In conclusion, B. distachyon ecotypes can protect soil from being eroded and improve water soil infiltration. The adaptation of B. hybridum to Mediterranean environments represents an interesting alternative as cover crop for typical woody agricultural plantations in Mediterranean soil such as olive groves, vineyards, and dry-fruit cropland.