Effects of soil conditioner on water content of sandy soil and peanut production under different irrigation rates were investigated during the two growing summer seasons of 2015 and 2016 at Abdel Moniem Reyad Village (Latitude 30°41'8" N, Longitude 30°18'0" E, and altitude of 7m above sea level), Al-Bustan area, El-Beheira Governorate, Egypt. Also, the validity of a simulation model to predict changes in soil moisture contents with time as well as moisture distribution within the soil profile was tested. Four soil conditioner levels (SC0: control, SC1: 1 ton/fed, SC2: 2 ton/fed, and SC3: 3 ton/fed), and three irrigation rates (full irrigation: 100% ETo, moderate deficit: 75% ETo and severe deficit: 50% ETo) were tested. Reference evapotranspiration (ETo) values were based on class A pan measurements. Peanut (Ismailia 2 cultivar) was used in the experiments. Results indicated that, the performance of the sprinkler irrigation system at the experimental site is considered acceptable. The additions of soil conditioner to the sandy soil led to decreasing the bulk density and saturated hydraulic conductivity values and increasing the saturated soil moisture contents, field capacity, welting point, available water, and air entry values. The tested simulation model proved to be accurate to predict changes in soil moisture contents with time as well as moisture distribution within the soil profile. Average seasonal values of applied irrigation water were 2986, 2240, and 1506 m3/fed for the 100, 75, and 50% ETo treatments, respectively. The tested treatments significantly affected peanut yield and yield components parameters tested under the experimental conditions. Applying amount of irrigation water equals to 100% ETo with 2 ton/fed of hydro-gel soil conditioner produced the highest pod yield of 1.83 and 1.89 ton/fed and straw yields of 1.33 and 1.32 ton/fed from the peanut crop grown in sandy soil.
Results indicated also that, an average water productivity value of 0.65 kg pod/m3 and 0.43 kg straw/m3 can be achieved from the interaction between 100% ETo * SC2 treatment. The results indicated that, in sandy soils of poor water retentive capacity, high yields of peanut crop can be obtained with the application of 2-3 ton/fed soil conditioner and irrigating with amount of water equals to 100% ETo.