Improving the productivity and profitability of irrigated rice production in Mauritania

Yield, input use, productivity and profitability of irrigated rice in Mauritania were analyzed during the 1997 wet season (July-December) in the Senegal river delta and middle valley, in collaboration with 42 large farmers and extension staff. Objectives were to determine agronomic constraints to rice cropping and to evaluate alternative crop management strategies aimed at overcoming these constraints. Grain yields ranged from 0.9 to 8.5 t ha(-1) and averaged 4.4 t ha(-1). Based on crop simulations, average yield potential in farmers' fields was estimated at 8.6 t ha(-1) indicating considerable scope for increased yields. Our survey identified the following main agronomic constraints: (i) mismatches between timing of nitrogen (N) fertilizer applications and critical N demanding growth stages of the rice plant; (ii) non-use of phosphorus (P) fertilizer on P deficient soils; (iii) largely neglected or inefficient weed management and (iv) late harvesting, often due to non-availability of combine harvesters. Based on these results we tested improved nutrient and weed management practices with farmers during the 1998 wet season. Improved nutrient management (i.e. T1: application of 20 kg P ha(-1) and 150 kg N ha(-1) in three splits at start tillering, panicle initiation and booting) increased yields by 0.9 t ha(-1). Improved weed management (i.e. T2: application of 6.0 L propanil ha (1) and 2.0 L 2,4-D-amine ha (1) at :2-3 leaf stage of weeds) also raised yields by 0.9 t ha(-1) as compared to farmers' practice (TP). The combined effect of T1 and T2 (i.e. T3) was additive: improving both nutrient and weed management raised yields by 1.8 t ha (1) over average farmers' yields of 3.9 t ha (1), i.e. an increase of almost 50%. The improved crop management practices were highly profitable: compared to farmers' practice, net benefits increased by 40% for T1 and T2 and by about 85%, for T3, with minimal additive investments. Inputs used for T3 are relatively easily available in Mauritania. We concluded that increased farmer awareness of the profitability of improved nutrient and weed management may have a tremendous impact on the competitiveness of rice production in Mauritania (C) 2001 Elsevier Science B.V. All rights reserved.