Forage and Food Legumes in a Multi-Year, Wheat-Based Rotation Under Drought-Stressed Conditions in Northern Syria’s Medium Rainfall Zone

Abstract

Long-term crop rotation trials were designed to assess sustainability of alternatives to traditional fallow and monocropping. The trial described here (6 years) involved wheat (Triticum aestivum L.) in rotation with lentil (Lens culinaris L.), forage vetch (Vicia sativa), pasture medic (Medicago spp.), fallow and watermelon (Citrullus vulgaris). Barley (Hordeum vulgare L.) was compared with wheat for an additional 2 years. Cereal grain and straw yields were highest with fallow and watermelon followed by vetch, lentil and medic; the latter showed no differential effect of variable grazing intensity. Fertilizer N increased yields except in the low-rainfall years (less than 250 mm). Barley out-yielded wheat in terms of grain, but not straw. Medic yielded highest in dry matter, whereas lentil produced highest seed yield. Despite the difficulty of assessing crop and animal-oriented rotations because of non-commonality of outputs, economic considerations are foremost, but other benefits of rotations (soil quality, water-use relations) are also relevant to the overall assessment of cereal-based Mediterranean rotations. The study suggested barley rather than wheat as the desired cereal in rotation with legumes in this marginal-rainfall (350 mm) environment and provided support for the viability of vetch and lentil in the cropping system. Given the importance of sheep in the region's farming system, vetch is likely to have a major role in crop rotations.