Combining Field and Simulation Studies to Improve Fertilizer Recommendations for Irrigated Rice in Burkina Faso

estimated at 4.0 to 4.5 t ha 1 (Illy, 1997; Wopereis et al., 1999), and in general two crops per year are grown. Development of improved fertilizer recommendations entirely based This compares to average yields in the Sahelian and on field experiments is time-consuming and costly. We employed a comSavannah regions of 3.0 to 5.5 t ha 1. The cropping bination of two simulation models and selected field data to develop intensity in Burkina Faso is higher than in most neighalternative fertilizer recommendations (AFR) for irrigated rice (Oryza sativa L.) in Bagré, Burkina Faso. Existing fertilizer recommendaboring countries (Matlon et al., 1996; Miézan and Sié, tions are 82 kg N ha 1 (wet season) or 105 kg N ha 1 (dry season), 1997; Wopereis et al., 2001). 31 kg P ha 1, and 30 kg K ha 1. The model RIDEV was used to imSegda et al. (2004) conducted an agroeconomic charprove timing of sowing date to avoid cold-induced sterility and timing acterization study in one of the most important rice irriof N fertilizer applications. The model FERRIZ was used to determine gated schemes in eastern Burkina Faso (Bagré irrigaAFR, based on estimations of indigenous nutrient supply for N, P, tion scheme) where development of irrigation is ongoing. and K; yield potential (Ypot); internal N, P, and K efficiency of rice; The analysis found agronomic constraints similar to the fertilizer N, P, and K recovery fractions; and fertilizer and rice prices. situation in other schemes of the region. Farmers’ net Simulations suggested decreasing P and K doses to 21 kg P ha 1 and benefits to irrigated rice cropping were mostly positive 20 kg K ha 1 but increasing the N dose to 116 kg N ha 1 in the wet in the dry season (DS) but often low or even negative in season (Ypot 8 t ha 1) and to 139 kg N ha 1 in the dry season (Ypot 9 t ha 1). Alternative fertilizer recommendations keep the P balance the wet season (WS). Yield gaps between average farmneutral, but a negative K balance was tolerated based on the high ers’ yield and best farmers’ yield were high and indicated soil K supply. Compared with existing recommendations, yield gains considerable scope for yield and profit increases in both of up to 0.5 t ha 1 were simulated at equal costs. These yield gains seasons. The observed medium to low average yields were more than confirmed in farmers’ fields during four consecutive are far below the level anticipated by authorities and growing seasons. Alternative fertilizer recommendations increased irrigation scheme planners. Limited productivity comgross returns above fertilizer costs by an average of about US$ 160 bined with high input prices cause low profit margins, per season compared with both farmers’ practice and existing recomwhich subsequently reduce savings for maintenance of mendations. infrastructure and machines and the reimbursement of credit. At current productivity levels, the economic viability of the irrigation schemes in the Sahel can be quesR is developing as a major staple food item of tioned (Bélières et al., 1997). Productivity increases are Burkina Faso. Demand has grown at an annual necessary to maintain the economic sustainability of irrirate of 3% between 1973 and 1992 compared with an angated agriculture in the region. nual population growth rate of 2.9%, which can be exBased on the agroeconomic characterization study, plained by changing consumer preferences (WARDA, Segda et al. (2004) concluded that the most promising 1996; Randolph, 1997). Currently, in-country producways to achieve higher productivity and input use effition covers about 60% of the demand, and 40% is met ciency are (i) to improve timing and quality of crop manfrom imports. While irrigated lowlands comprise only agement practices and (ii) to improve existing fertilizer about 20% of the total rice area, this system is characterrecommendations (EFR). Fertilizer recommendations ized by considerably higher yields and contributes about in Burkina Faso have not changed since introduction 50% to national rice production (INERA, 2002). Irriof irrigated rice and are presently uniform over large gated systems were introduced in the 1960s, and the areas and cut across diverse climatic and edaphic envidevelopment was accentuated from the 1970s onward. ronments. Especially the widespread use of compound Average yields of irrigated rice in Burkina Faso were fertilizers, not tailored to the needs of the rice crop, constitutes an obstacle for optimization of nutrient manageZ. Segda and M.P. Sedogo, Institut de l’Environnement et de Recherment. Other factors included problems with collective ches Agricoles (INERA), 04 BP 8645, Ouagadougou 04, Burkina and individual planning of the cropping calendar for Faso; S.M. Haefele, West Africa Rice Development Association double cropping of rice (two rice crops on the same field (WARDA), BP 96 St. Louis, Senegal (current address: International per year) and the need to also attend to rainfed crops Rice Research Institute, DAPO Box 7777, Metro Manila, Philippines); outside the scheme. M.C.S. Wopereis, An International Center for Soil Fertility and Agricultural Development (IFDC)–Africa Division, BP 4483, Lomé, Togo; To improve existing crop and nutrient management and S. Guinko, Université de Ouagadougou (UO), 03 BP 7021 Ouagadougou 03, Burkina Faso. Received 14 Nov. 2004. *Corresponding Abbreviations: AFR, alternative fertilizer recommendations; DS, dry author ([email protected]). season; EFR, existing fertilizer recommendations; FP, farmers’ practice in terms of fertilizer use; IKS, indigenous soil potassium supply; Published in Agron. J. 97:1429–1437 (2005). Rice INS, indigenous soil nitrogen supply; IPS, indigenous soil phosphorus supply; IS, indigenous soil nutrient supply; RF, recovery fraction of doi:10.2134/agronj2004.0275 © American Society of Agronomy applied fertilizer nutrients; TFC, total fertilizer cost; WS, wet season; Ypot, yield potential. 677 S. Segoe Rd., Madison, WI 53711 USA 1429 Published online September 19, 2005