Analysis for Improved Sowing Date for Winter Faba Bean in Morocco

Faba bean (Vicia faba L.) is a useful grain legume for production in Mediterranean climates due to its consumption as food for humans and feed for animals, and its ability to symbiotically fix atmospheric nitrogen. Currently, in Morocco a substantial fraction of faba bean is sown under a rainfed management scheme in which the crop is sown after about a 15-day delay following the first rains after the dry season. The 15-day delay allows weed seeds to germinate and be killed during land tillage prior to sowing of faba bean. However, the 15-day delay shortens the growing season and may negatively impact seed yield. Two alternate sowing date criteria were simulated for faba bean sowing date in Morocco as approaches to increase production. In addition to the 15-day delay management by farmers, sowing was simulated to occur immediately following accumulation of 10 mm or 25 mm of water in the soil. A geospatial analysis was undertaken using the SSM-faba bean model to simulate production on a 1° × 1° grid across Morocco. Eighty three locations were each simulated for 30 growing seasons of weather input. The simulation results for the 25-mm sowing date criteria resulted in decreased geographical area in which faba bean could be grown while the 10-mm sowing date criteria resulted in an expanded geographical area for faba bean production. The average yield based only on seasons in which sowing was achieved, was fairly stable among the sowing-date criteria. The probability of yield increase of the 10-mm sowing date criterion as compared to the 15-day delay sowing was greater than 50% in much of the area found suitable for faba bean production. Assuming an acceptable method for weed control for the 10-mm sowing date criterion, this alternate management could expand faba bean production in Morocco as compared to the current practice of a 15-delay in sowing date.