WILKO SCHWEERS1, THEIB OWEIS1, ARMIN RIESER2
1ICARDA, Natural Resource Management Program, Syria
2University of Bonn, Institute for Irrigation, Drainage, and Land Improvement, Germany
Groundwater is a scarce resource in Khanasser valley, northwest Syria. Its use is limited by groundwater yield and salinity. About 50 per cent of the total groundwater abstractions are applied to wheat, predominantely bread wheat (Triticum aestivum L.) by sprinkler irrigation (average EC: [5.8]dSm) and basin irrigation (average EC: [10.0]dSm). In order to investigate the potential for increasing groundwater use efficiency in Khanasser valley or similar dry areas, the effects of different application rates on yield and income of wheat were evaluated. Two experiments were conceived, one using sprinkler irrigation (Trial A), the other basin irrigation (Trial B). Each trial with 4 replications included the following treatments: Full supplementary irrigation, farmers' treatment and rainfed control. These were compared with deficit irrigation (Trial A) and leaching (Trial B). The experiment was managed in cooperation with the farmers. Soil salinity was recorded before and after the experiments; soil moisture was monitored with the neutron probe at regular intervals. Due to high evaporation rates in the spring, the farmers (Trial A) had difficulties to bring the soil moisture back to field capacity as this delayed their irrigation schedule. The use of different application rates in the basins (Trial B) was constrained by insufficient land levelling. Frost in early April 2004 (-7°C) severely damaged the emerged ears in one field, which had been planted 10 days earlier than the rest. Apart from this specific effect, yield differences between the sites were due to water applications, the salinity of the irrigation water and the irrigation method. The experimental approach and the results were discussed with the farmers and conclusions were drawn for the design of consecutive trials.
Keywords: Dry areas, groundwater resources, soil salinity, supplementary irrigation, Syria