Improving yields and reducing risks in pearl millet farming in the African Sahel

Over 40 years of research on pearl millet farming in the semi-arid Sahel has not been extended to farmers successfully. The recommendations for proper planting density, inorganic fertiliser application, and short cycle varieties have not been followed by the farmers. The difference in priorities between researchers, who aim to improve yields in average years, and Sahelian farmers, who seek to reduce the frequency of crop failure, could explain the non-adoption of most innovations because the risks of yield losses were not reduced. Innovations and conventional techniques were tested in farmers' fields in Niger over 5 years in two experiments. The first experiment (3 years) compared four hill densities with and without nitrogen and phosphorus (NP) fertilisation. Soil water was monitored with neutron probes. Grain yield, biomass, and tillering were modified profoundly by rainfall distribution, and treatment effects were statistically significant in two out of three years. The conventional low density planting did not produce high yields as frequently as higher densities under favourable conditions; however, there was less crop failure under harsh conditions with low density farming, although lower average grain yields were realised. Risks to crop yields were reduced mainly by the staggered development of main stem and tiller panicles. The tiller contribution to yields was reduced from about 60% in conventional wide spacing (5000 hills ha⁻¹) to 20% in recommended spacing (10,000 hills ha⁻¹). The second experiment (3 years) compared NP fertilisation versus no inorganic inputs in 11 fields of variable nutrient status under conventional low density planting. Grain yields improved with NP application in all fields because of the increase in panicle number. But contribution of the tillers to yields did not increase in the poorest soils because higher yields were obtained by reducing the number of sterile hills. This study allowed the grouping of farming practices according to their potential to improve yields or reduce risks. The practices that increased yields and reduced risks were: conventional low density planting with or without inorganic fertiliser, planting of late and early maturing varieties during the same season, and manuring. The practices that increased yields but did not reduce risks were: dense planting with inorganic fertilisation, mono-cropping of early maturing varieties, and incorporating inorganic fertiliser in very poor soils. Under the marginal conditions of the Sahel, farmers are likely to accept practices that increase yields and reduce risks.