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Book: Challenges and Strategies of Dryland Agriculture
Published by: Crop Science Society of America and American Society of Agronomy



  1.  p. 219-227
    CSSA Special Publication 32.
    Challenges and Strategies of Dryland Agriculture

    Srinivas C. Rao and John Ryan (ed.)

    ISBN: 978-0-89118-611-3


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Sustainable Barley-Legume Rotations for Semi-Arid Areas of Lebanon

  1. Sui-Kwong Yau,
  2. Mustapha Bounejmate,
  3. John Ryan and
  4. Adel Nassar
  1. American University of Beirut, Beirut, Lebanon
    ICARDA, Aleppo, Syria
    ICARDA, Terbol, Bekaa, Lebanon


In semi-arid areas of West Asia and North Africa with a Mediterranean-type climate merging into a continental one, farmers have been increasingly practicing more continuous barley (Hordeum vulgare L.) cultivation, which is likely to be unsustainable in the long run. The objectives of the study were to: (i) determine if barley monoculture is really unsustainable, (ii) ascertain if barley and total dry matter yields can be increased and sustained by including a legume in the rotation, and if so, (iii) determine which barley-legume rotation is more productive in terms of dry matter. A long-term rainfed cropping trial, which was the first of its kind in Lebanon, was conducted at the Agricultural Research and Education Center in Lebanon's Bekaa Valley (512 mm annual precipitation). Eight different two-phase, barley- based rotations were compared. Thus, barley was grown after: barley, lentil (Lens culinaris Medik.), common vetch (Vicia sativa L.), bitter vetch [V. ervilia (L.)Willd.], common vetch for grazing, medics (Medicago spp.) for grazing, common vetch for hay, and common vetch with barley for hay. Seed and straw yield under barley monoculture declined after 3 yr to about 50% of the trial mean yield due to severe infestation of wild barley [Hordeum spontaneum (C. Koch) Thell.]. In the barley phase, barley-legume rotations yielded more seed and straw, and had higher stability than the barley monoculture. In the legume phase, all the legume treatments, except medics, yielded more dry matter than barley monoculture. For total dry matter per rotation cycle, barley in rotation with common vetch for seed and straw gave the highest yield and the lowest coefficient of variation (CV). In conclusion, the study showed that barley monoculture is unsustainable, and that barley and total drymatter yields could be sustained by including a legume in the rotation. Thus, farmers in the semi-arid areas of Lebanon should adopt a barley-legume rotation, such as barley-common vetch.

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