Pierre Akponikpe

Integrated nutrient management of pearl millet in the Sahel combining cattle manure, crop residue and mineral fertilizer

In the Sahelian zone of Niger, there is a need to develop guidelines fir integrated nutrient management, which relies on the potential nutrient sources of manure, pearl millet residue and mineral fertilizers. A fully factorial on-station experiment was conducted during the 1994 and 1995 rainy seasons at Sadore, Niger, combining application of: (i) broadcast millet residue (300, 900 and 2700 kg ha(-1)), (ii) broadcast cattle manure (300, 900 and 2700 kg ha-(1)) and (iii) mineral fertilizer (unfertilized control, 15 kg N ha(-1) + 4.4 kg P ha(-1) and 45 kg N ha(-1) + 13. l kg P ha(-1)). Manure and fertilizer increased millet yields in both years whereas residue was effective in 1995 only: The effect of manure and residue were additive, as was the effect of manure and fertilizer but only up to 50 kg N ha(-1). However in 1995, the response to fertilizer was approximately doubled in the presence of 900 or 2700 kg residue ha(-1) compared to fertilizer with 300 kg ha(-1) residue, indicating a strong synergistic effect. This synergistic effect was reflected in the partial factor productivity of nitrogen and phosphorous in both years. Two treatment combinations stand out as particularly relevant based on yield, partial factor productivity and nutrient balance criteria: 2700 kg manure ha(-1) combined with (i) 300 kg residue and no fertilizer (95% grain yield increase); (ii) 900 kg residue ha(-1) and 15 kg N + 4 kg P ha(-1) (132 % grain yield increase). There is a need for similar, long-term experiments to confirm the present results.

Soil water crop modeling for decision support in millet-based systems in the Sahel: a challenge

Food insecurity in the Sahelian environment was extensively shown to be a result of low soil fertility and high climate risks. But decisions and recommendations made from the great wealth of research have little been adopted by farmers. Soil water crop models (SWCM) can assist researchers and development actors in this environment if they can appropriately deal with the constraints and mainly farmers agricultural development goals.

Efficient use of nutrients and water through hill-placed combination of manure and mineral fertilizer in smallhoder maize farming system in northern Benin

Maize, a major staple food in many farming systems in sub-Saharan Africa, is characterized by low productivity due to the scarce availability and use of external inputs and recurrent droughts exacerbated by climate variability. Within the integrated soil fertility management framework, there is thus a need for optimizing the use of fertilizers and manure for the efficient use of limited nutrient resources and rainfall, and to increase crop yield and farmer income. On-station experiments were conducted in Northern Benin over a 4-year period using a split-plot design with three replications to evaluate the effect of hill-placed mineral fertilizer and manure on yields and soil chemical properties. The treatments consisted of the combination of: (i) three rates of manure (main plot): 0, 3 (3M) and 6 (6M) t ha−1; and (ii) three levels of fertilizer (sub-plot): 0%(NF), 50% (50F) and 100% (100F) of the recommended rate (76 kg N + 13.1 kg P + 24.9 K ha−1). Hill-placement of manure and/or fertilizer significantly improved soil organic carbon content, available P and exchangeable K in the vicinity of the planting hills. As a result, yields increased steadily over time for all manure and fertilizer combinations, with yields up to 5 times higher than the control for the 6M-100F treatment. Value-cost ratios and benefit-cost ratios were >2 and generally as good or even better for treatments involving 50F compared to NF or 100F. Although applying half the recommended rate of fertilizer is performed by many farmers and appears to make economic sense, this practice is unlikely to be sustainable in the long run. Substituting 50F for 3M or complementing 50F with 3M are two possible strategies that are compatible with the precepts of ISFM and provide returns on investment at least as good as the current practice. However, this will require greater manure production, made possible by the increased stover yields, and access to means of transportation to deliver the manure to the fields.