Dual-purpose crops for grain and fodder to improve nutrition security in semi-arid sub-Saharan Africa: A review

Addressing the challenge of food and nutrition insecurity in Sub-Saharan Africa (SSA) will require innovative agriculture production systems that support multiple objectives. In recent years, several high-yielding, and nutrient-dense varieties of cowpea (Vigna unguiculata (L.) Walp), pearl millet (Pennisetum glaucum (L.) R. Br.), and sorghum (Sorghum bicolor (L.) Moench) have been developed purposely as dual-purpose (DP) varieties in SSA to meet human nutrition and livestock feed needs. This review synthesized published data on DP varieties from cowpea, pearl millet, and sorghum. Findings showed that DP crops and varieties were largely grown by smallholder farmers in a variety of soil and climatic conditions with production systems characterized by large gaps between attainable and actual crop yields which varied significantly among regions. While the grain and fodder yield of traditional varieties (TV) of cowpea averaged 700 kg ha⁻¹ and 860 kg ha⁻¹, respectively, the reported grain yield of DP varieties was 1100 kg ha⁻¹ and 2150 kg ha⁻¹ for fodder. The average grain yield of TV millet varieties was 750 kg ha⁻¹ and 2500 kg ha⁻¹ for fodder. Similarly, average grain yield for DP millet varieties was 2000 kg ha⁻¹ and 4200 kg ha⁻¹ fodder. Dual-purpose sorghum varieties yielded greater grain (>3000 kg ha⁻¹) and fodder (3500 kg ha⁻¹) compared to TV. Little data were obtained on the nutritive qualities of cowpea, millet, and sorghum DP varieties. However, DP millet varieties were reported to be more digestible than TV varieties. Furthermore, adoption of DP varieties improves fertilizer use efficiency, profitability, environmental sustainability, and resilience of the whole farm system compared to TV. Considering fertilizer's high prices, availability, and quality in semi-arid countries in addition to farmer poverty level, economic evaluation and environmental impact assessment are critical before wide dissemination.