Field experiments were conducted during the season (2018-2019), and located at Grace village, Ashmun center, Menoufia governorate. The soil was clay loam in texture and classified as old alluvial soil of the Nile Delta. The main objective of this study was to determine the optimum depth of lateral irrigation beneath the soil surface of the subsurface drip irrigation system line of maize crop. Three levels of water application rate were 60%-70% and 80% of potential evapotranspiration (ETp). The study also aimed to determine water use efficiency (WUE) of maize (High tech 2031) in the case of using subsurface drip irrigation (SSDI). Also, the study aimed to drive the effect of using polymer (PAM) on maize yield.
The contour maps of soil moisture content distribution showed that it reached to about 90.4% at 25 cm of lateral depth with polymer addition (PAM) case at 80% ETp. The higher values of electrical conductivity (Ec) were 3.3 ds/m and 3.7 ds/m recorded at 15 cm of lateral depth by irrigation without polymer addition (N.PAM) and irrigation with polymer addition (PAM), respectively at 60% ETp. The higher value of total root weight was 6.3 g occurred at 80% ETp and increased by about 4.9%, at 25 cm of lateral depth with (PAM) compering with (N.PAM). The higher values of water use efficiency (WUE) at a lateral depth of 25 cm with polymer addition (PAM) case at 80% ETp.
Irrigation at 80% of reference evapotranspiration (ETp) with subsurface drip irrigation system at 25cm of lateral depth increased significantly vegetative growth (plant height, leaves area, and ears no/plant, as well as the weight of ears and weight of grain yields (Mg/fed). While irrigation at 60 or 70% of reference evapotranspiration (ETp) with subsurface drip irrigation system at the two tested depth of lateral line beneath the soil surface resulted the lowest values of the growth parameters of maize.