Distribution of wild annual legume species in Morocco and relationship with soil and climatic factors

Abstract

Pods and seed of all annual legume species and a soil sample were collected within a 1 m2 sample area at each of 161 sites in Morocco, and the surrounding area of approximately 0.5 ha intensively searched for all species. This paper reports findings for all genera except Medicago and Trifolium which are the subject of separate papers. Annual legumes were found at 138 sites and 15 genera and 31 species were identified. Scorpiurus sulcata, the most prolific species, was found at 117 sites, followed by Astragalus hamosus (52 sites) and Hippocrepis unisiliquosa (30 sites). The distribution of the genera was related to pH, sand and clay content, altitude and rainfall, but very little to soil nutrient status. The highest pod yield was 890 kg/ha for Scorpiurus sulcata whilst Hedysarum coronarium had the highest average pod yield of 392 kg/ha but occurred at only 3 sites. Scorpiurus had the highest average pod yield of any genus that occurred at more than just a few sites. Overall pod yields were strongly related to sand and clay content of the soil, rainfall and minimum temperature and to a lesser extent, to altitude and soil potash. The most significant finding was the widespread distribution of Scorpiurus sulcata which did not appear to have any specific requirements for soil type, soil nutrient status, altitude or climate. The need to assess Scorpiurus sulcata as a potential pasture plant for Morocco and other areas of similar climate is clearly indicated.