Improving the productivity and profitability of irrigated rice production in Mauritania

Yield, input use, productivity and profitability of irrigated rice in Mauri tania were analyzed during the 1997 wet season (July-December) in the Seneg al river delta and middle valley, in collaboration with 42 large farmers an d extension staff. Objectives were to determine agronomic constraints to ri ce 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 potent ial in farmers' fields was estimated at 8.6 t ha(-1) indicating considerabl e scope for increased yields. Our survey identified the following main agro nomic 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 du e to non-availability of combine harvesters. Based on these results we test ed improved nutrient and weed management practices with farmers during the 1998 wet season. Improved nutrient management (i.e. T1: application of 20 k g 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 man agement (i.e. T2: application of 6.0 L propanil ha (1) and 2.0 L 2,4-D-amin e 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 yield s by 1.8 t ha (1) over average farmers' yields of 3.9 t ha (1), i.e. an inc rease of almost 50%. The improved crop management practices were highly pro fitable: compared to farmers' practice, net benefits increased by 40% for T 1 and T2 and by about 85%, for T3, with minimal additive investments. Input s used for T3 are relatively easily available in Mauritania. We concluded t hat increased farmer awareness of the profitability of improved nutrient an d weed management may have a tremendous impact on the competitiveness of ri ce production in Mauritania (C) 2001 Elsevier Science B.V. All rights reser ved.