Water use Efficiency of Maize Crop under Deficit Irrigation Scheduling using Gravity Drip System in Samaru, Nigeria

Abstract

The use of gravity fed drip irrigation systems is fast gaining popularity in Northern Nigeria. The drip kit uses gravity instead of a pump to provide the head (energy) for its operation. The water source (a tank or bucket) is usually place some meters above the ground to provide the pressure head. In the study reported herein, a field experiments were carried out at the Institute for Agricultural Research (I.A.R) irrigation farm Samaru-Nigeria during 2012/2013 irrigation season to evaluate the effect of deficit irrigation scheduling, using the gravity drip kit, on yield and water use of a maize (SAMAZ 14 variety) crop. The field experiment consisted of eight treatments replicated three times. The treatments comprises of a control treatment which was given full irrigation (irrigated at 100 % water requirement) and a full deficit treatment which was irrigated at 50 % water requirement. The other treatments were irrigated at 50 and 75 % of water requirement at different growth stages of the maize crop. The irrigation interval was alternated between three and four days. The drip system layout consisted of three drip lines of 5 m long each per treatment, given a total of 72 lines for the entire field. The drip tape was 16 mm diameter with in-built emitters spaced 30 cm interval. The drip lines were spaced 60 cm apart in each treatment, and a 2000 litres capacity GeePee tank placed 3 m above the ground was used to supply water. The hydraulic performance was drip system was evaluated, grain yield and crop water use were measured and crop water productivity was computed. The average variation of the emitter flow rate was found to be 19.7 %, the emission uniformity was 92 %, while the distribution uniformity was 91.9 %; which implies even distribution of water through the drip system. The average discharge coefficient of variation was 6.34 % and the average coefficient of variation uniformity was calculated as 93.6 %. The overall application efficiency of the system was 92.2 %. The overall average dripper discharge was found to be 0.557 liter/hr. Grain yield ranged between 1.56 and 3.39 t/ha, seasonal crop water use varied from 320 to 483 mm and crop water productivity ranged between 0.41 and 0.63 kg/m3. The drip system was found to be very effective in administering deficit scheduling with high water application efficiency. The highest crop yield, seasonal water use and water productivity were obtained in the treatment that was fully irrigated, which implies that the deficit irrigation did not improve the crop response or water use efficiency. The results suggest that with gravity drip irrigation system, deficit irrigation practice will not lead to higher crop water use efficiency of the maize crop.