Rice production with less irrigation water is possible in a Sahelian environment uri icon

abstract

  • We investigated the possibility of saving irrigation water in rice production in a Sahelian environmentwith different nitrogen rates and weed control treatments. A series of field experiments was conductedat Ndiaye (shallow water table, dry and wet season) and at Fanaye (deep water table, wet season) inSenegal with four irrigation treatments, involving three water-saving regimes using alternate wetting and drying (AWD) and a flooded control, and three weed management treatments. This was followed bytwo experiments with the same four irrigation treatments in combination with three nitrogen (N)application rates, at the same locations. Hence four irrigation regimes were tested over three seasons.Between 480 and 1060 mm of irrigation water was used in the water-saving treatments compared with800–1490 mm in the flooded-rice treatment. Rice yields ranged from 2.3 to 11.8 t ha_1 in the watersavingtreatments, whereas in the flooded control the yields ranged from 3.7 to 11.7 t ha_1. In the wetseason (WS), the treatments in which AWD was applied during part of the season resulted in the highestyields at both sites. In the dry season (DS), the continuously flooded treatment out-yielded othertreatments, with the exception of AWD in Fanaye.At the Ndiaye site, the control of weeds increased yields from on average 2.0 to 7.4 t ha_1 in the DS and from 1.4 to 4.9 t ha_1 in the WS. No weed control in combination with AW D during the vegetative stagereduced yields to below 1.0 t ha_1. However, when weeds were controlled, crop yields obtained with acombination of AWD and flooding were comparable with those obtained in fully flooded plots receivingthe same weed management at both sites in the 2005 WS. Increasing rates of N significantly increasedgrain yield. Internal N efficiency was poorer at Ndiaye than at Fanaye suggesting that yields in Ndiaye areconstrained by other factors than N. In Ndiaye, agronomic N use efficiency was smaller in the AWDtreatments compared with fully flooded conditions.This study demonstrates that it is possible to save irrigation water and improve water productivity inrice grown in a Sahelian environment. An irrigation regime for rice that starts as conventional (flooded),and then changes to AWD can save water with little or no yield loss, while maintaining low weedpressure and efficient use of N

publication date

  • 2012