Changes in organic matter and nitrogen with a cereal-legume rotation trial
1997
Ryan, J. | Masri, S. | Garabet, S. (ICARDA, Aleppo (Syria)) | Harris, H.
Farming systems in West Asia - North Africa involve rotations of cereals with fallow or food/forage legume crops depending on location and rainfall. Barley (Hordeum vulgare L. subsp. vulgare) tends to dominate in the drier zones and wheat (Triticum aestivum L. subsp. aestivum, and T. turgidum L. subsp. durum (Desf.) Husn.) in the more favorable areas. Sheep and goats are integral parts of the systems, particularly those dominated by barley. ICARDA is developing improved cultivars and management practices and needs to critically examine the merits of several systems in terms of efficiency, costs and sustainability. Therefore, a long-term trial was established in the 1983/84 season at ICARDA's main research station at Tel Hadya, near Aleppo in northern Syria, to evaluate the productivity of systems in which durum wheat is rotated with vetch (Vicia sativa L.), lentil (Lens culinaris Medik.), chickpea (Cicer arietinum L.), medic pasture (Medicago spp.), wheat, watermelon (Citrullus vulgaris L.), and fallow. Various N levels (0, 30, 60, 90 kg ha-1) and intensities of grazing stubble (heavy, moderate, none) were imposed on the wheat phase. Both the wheat and the alternate phase were included each year. While seasonal rainfall, which ranged from 210 to 486 mm, and residual soil moisture after the alternate phase dictated the magnitude of wheat yields, N increased water-use efficiency. Soil N levels (mineral, total) varied with the system and were highest for medic and least for wheat and fallow. Similar differences were evident for organic matter, which also tended to increase with increasing N level. Though the trial needs to continue for several more years, the impact of some crops (i.e., medic) on soil quality is already apparent
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