Water Requirement and Water Productivity of Cowpea (Vigna unguiculata [L.] Walp.) Crop in Two Agro-ecological Zones of Sennar State, Sudan

Abstract

A field experiment was conducted in two agro-ecological zones in Sennar State, Sudan during seasons2014/2015 and 2015/2016to estimate crop water requirement and water productivity of cowpea (Vigna unguiculata L. Walp) under three farming systems (conventional farming (CF), conservation agriculture (CA) and Water Harvesting (WH).The agro-ecological zones were semi-arid zone (Sennar Research Station Farm) and semi-humid zone (Abu Naama Research Station Farm). The Weather and crop data were collected during the study period. CROPWAT 8.0software was used to compute reference evapotranspiration (ET_O), crop factor (K_c) and the crop water requirement

(ET_C). The analysis showed that the average values of ET_O rangedbetween1.2 and5.0 mm/day in semi-arid zone, and between1.56and4.86 mm/day in the semi-humid zone. The average K_c values during the initial, development, mid-season and late-season stages were 0.45, 0.79, 1.08and 0.84, respectively, while the average values of cowpea water requirements during initial, development, mid-season and late-season stages were 37.4, 71.3, 149.5 and 77.0 mm for the semi-arid zone and 34.1, 65.8, 130.6 and 77.3 mm for the semi-humid zone. The average water requirement was 3350 m³/ha and 3050 m³/ha in the semi-arid and semi-humid zones, respectively. The water productivity for cowpea crop in the semi-arid zone was 0.33 kg/m³ and 0.35 kg/m³ in semi-humid zone. The WH and CA farming system gave better results compared to the CF for cowpea production in dryland areas of Sennar state