Introducing forage legumes into cereal crop rotations can have a number of benefits. In addition to providing nutritious fodder, soil fertility improves and cereal yields are maintained, resulting in a more sustainable production system. ICARDA recently completed a long-term collaborative study of the use of legumes in barley rotations in WANA. As a result, researchers have identified barley/legume rotations that increase crop yields and reduce weed problems. These were found to be agronomically efficient alternatives to unsustainable continuous barley cropping, in which yields declined. The higher yields of both grain and feed in the new rotations will greatly improve the net incomes of farmers in the region.

Barley/legume rotations for semi-arid areas of Lebanon

In the arid and semi-arid areas of WANA, continuous barley cultivation is increasing. In such environments, barley is the dominant winter crop, as it tolerates dryness, poor soils and salinity better than wheat, and usually gives a higher grain yield. Sheep husbandry and barley cropping are the most important agricultural activities in the region, and barley grain is the traditional, and most used, sheep feed. After the grain harvest, barley straw and stubble are also important feed sources in the summer. In years when barley production is poor, farmers often do not harvest their mature barley, but simply let their sheep graze the crop in the field instead.
Inadequate feed supplies and high feed prices are some of the main problems reported by farmers in the region, where the number of sheep and goats being kept has increased rapidly. The increased demand for feed has led farmers to grow barley continuously, rather than using their traditional barley/fallow rotations. Though this practice can provide short-term economic benefits, there are concerns regarding its long-term sustainability, as cereal monocultures can deplete soil nutrients and increase pest and weed populations, leading to reductions in yields and farmers' returns. A sustainable and productive option to replace barley monoculture is urgently needed.
Crop rotations have been widely used to increase the sustainability of farming systems, and the planting of legumes in rotation with cereals has been beneficial in many semi-arid areas. However, feed legumes have not been widely adopted by farmers in WANA. Therefore, in order to identify sustainable, more profitable, and more environmentally friendly alternatives to cereal monoculture, researchers from ICARDA and the American University of Beirut designed a long-term rotation trial in Lebanon. The objectives of the study were (1) to determine whether continuous barley monoculture is unsustainable, (2) to ascertain whether barley and total dry matter yields can be increased and sustained by including a legume crop in the rotation, and (3) to determine which barley/legume rotations are most productive. The trial was initiated, under rainfed conditions, in the 1994/95 growing season, at the Agricultural Research and Educational Center in Lebanon, in collaboration with the Lebanese Agricultural Research Institute (LARI).
Eight two-phase barley-based rotations were compared. These comprised barley in rotation with crops grown for their seed (lentil, common vetch, bitter vetch); crops grown specifically to be grazed in situ (common vetch, medics) and crops grown for hay (common vetch and common vetch mixed with barley). The eighth rotation, barley/barley, represented the continuous barley monoculture currently used by many farmers to produce seed (and straw).

and because of the lower N content of the soil and the higher yield instability associated with continuous barley cropping, farmers in the northern Beka'a Valley, Lebanon, should discontinue barley monoculture and adopt a barley/legume rotation. Barley monoculture has been found to be unsustainable, but barley yields could be increased and sustained by including legumes in the rotation. Because of the higher yields they provide, the net incomes from barley/legume rotations would be much higher than those obtained from barley monoculture.