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are low despite the potential for increased production. One of the reasons for low
productivity in Kurdistan is the dependence on rain for watering the crop. Most of
the wheat in the region is rainfed and moisture stress adversely affects yields. The
region is, however, blessed with hills and valleys which generate ample runoff dur-
ing the wet season which could be captured for use during dry spells.
ICARDA, the General Directorate of Agriculture Research & Extension of IKR
and Japanese International Cooperation Agency (JICA) implemented a study in
Zurgaziraw near Erbil City in IKR in 2014–2015 on the use of water harvesting
techniques to provide supplemental irrigation to wheat crops. The site has an aver-
age annual rainfall of 250 mm and is located at the foothill of a series of mountains
which allows ample runoff from the mountains to flow through the site. Simeto
wheat cultivar was sown on November 21, 2014, at a rate of 128 kg ha−^1. Due to the
very low rainfall, three treatments were tested: (1) 0.25 ha (plot A) with 200 mm
supplemental irrigation; (2) 0.25 ha (plot B) with 100 mm supplemental irrigation;
and (3) 0.25 ha (plot C) under rainfed (control).
An important constraint to SI is the availability of water resources when irriga-
tion is needed. Groundwater or surface water may be available in some places but
often not. In these situations, rainwater harvesting can be used to collect runoff
water and store it for use as SI. In Iraq, a six-step process (Fig. 1 ) was followed: (1)
selection of a suitable site with steep, sloped, barren land generating non-beneficial
runoff; (2) design and excavation of a water harvesting reservoir; (3) reservoir lined
to prevent seepage and reinforced with a spillway and rocks to prevent rupture; (4)
reservoir monitored for water collection and maintenance during the wet season; (5)
sprinkler system designed and installed in the field towards the end of the wet sea-
son; and (6) soil moisture monitored using a measuring device with supplemental
irrigation applied to both treatment plots (plot A: 200 mm SI; plot B: 100 mm SI)
each time the moisture level dropped below 30 % of field capacity. At maturity, the
crop was harvested from three 1 m^2 plots in each treatment (nine plots in total) to
calculate yield, spikes and grains per unit area.
Ten supplemental irrigation doses were applied to both treatment plots (A and
B). Since the total amounts were set at 200 and 100 mm for plots A and B, respec-
tively, the amount received in each irrigation application operation for plot B was
half of plot A.
Crop yield increased, on average, by 91 % (0.75 t ha−^1 under rainfed versus 1.43
t ha−^1 under 100 mm SI treatment) with the addition of 100 mm supplemental irriga-
tion, compared with rainfed only plots. With 200 mm of supplemental irrigation,
crop yield increased, on average, by a further 112 % (3.03 t ha−^1 under 100 mm SI
treatment versus 1.43 t ha−^1 under 100 mm SI treatment) on top of the 91 % increase
achieved by switching from rainfed to 100 mm SI (Table 2 ).
V. Nangia and T. Oweis