Eritrea, a largely arid or semi-arid country in north-east Africa, lies on the western side of the Red Sea between about 12 and 18° N, and has an elevation ranging from -75 m to 3,018 m asl. Soils span from shallow, often infertile stony soils in steeper areas to fertile clays and clay loams on the flats. Soil pH ranges from slightly acid to moderately alkaline. About 80% of the population is engaged in subsistence mixed farming, with livestock being used for meat, milk, draft and fiber, as well as serving as a financial reserve. Average farm size in the most intensively populated area (central highlands) is about 0.2 ha, and about 2 ha in the less populated western lowlands. In extensive farming systems, the rangelands that account for more than 90% of livestock feed, have a carrying capacity ranging from about 20 ha/Tropical Livestock Unit (TLU one bovine with a body weight of 250 kg) in the 100 mm rainfall zone to about 4 ha/TLU in the 600 mm rainfall zone (Kayouli et al. 2002). Crop residue is the second largest source of feed for livestock, with sorghum residue being the most important by a large margin. In the more intensive dairy systems, perennial forages such as Medicago sativa cvv. Hunter River (uplands) and Hairy Peruvian (lowlands) and Pennisetum purpureum are used by some farmers. Columbus grass (Sorghum x almum) has been introduced in limited areas in recent years. The combination of an extensive and diverse livestock population, and unreliable and strongly seasonal rainfall, has contributed to widespread overgrazing, which in turn has led to significant loss of ground cover and soil erosion. Much of the native grassland is now severely degraded, and more productive endemic species largely lost.
