Estimating water consumptive use for some crops under stress conditions using neutron scattering method

Field experiment was conducted to study the influence of different levels of irrigation water salinity on actual evapotranspiration, water stress coefficient, yield and water use efficiency of both groundnut and wheat crops growing on sandy soil under trickle irrigation system located at 30º 24 N latitude, 31º 35 E longitude while the altitude is 20 m above the sea level,Four irrigation water salinity levels were used for both crops, they are; 2.4 (S1), 2.7 (S2, 3.3 (S3) and 4.4 (S4) dS m-1, for groundnut and 4.9 (S1), 6.3 (S2), 8.7 (S3) and 13 (S4) dS m-1, for wheat respectively besides a fresh water (FW) as a control treatment (0.5 dS m-1). Cattle manure was added as a soil amendment at a rate of 48 m3 ha-1. Neutron moisture meterwas used to determine soil moisture content and depletion through the soil depths of 30, 45, 60, 75 and 9Ocm, Soil moisture content at 15 cm soil depth was determined gravimetrically. The applied irrigation water was 700 mm/season for groundnut and 550 mm/season for wheat based on 100 % of the recommended crop water requirements according to F AO No.33. (1979). The obtained results showed that the actual evapotranspiration (ETa) and water stress coefficient (Ks) were slightly deceased by increasing the salinity of irrigation water especially under (S4) irrigation salinity treatment for both crops. Regarding the yield, water use efficiency (WUE) and irrigation water use efficiency (IWUE) of groundnut and wheat, results showed that the high salinity of irrigation water decreased both yield; WUE and IWUE. The yield of groundnut follows the order FW (3.89 ton ha-1) S1 2.19ton ha-l) S2 (1.63 ton ha-l) S3 (1.54 ton ha-l) S4 (1.19 ton ha-l)whereas wheat yield follows the order FW (6.05 ton ha-l) S1 (4.99 ton ha -l) S2 (4.91 ton ha-l) S3 (4.63 ton ha-l) S4 (2.91 ton ha-1 )Concerning soil chemical properties; the salinity of irrigation water significantly increased the total soluble salts of soil (ECe)).