Effect of Treated Wastewater by Binary Irrigation on Soil Physical Properties

Abstract

A field experiment was conducted to determine water requirements for mays crop for fall season of 2013 in the field of Zafaraniyah Station – Ministry of Agriculture, 30 km south of Baghdad, 44.4˚ longitude, 33.14 latitude and 34 m elevation. The experiment was designed according to RCBD with three replicates and treatments were distributed randomly on experimental plots. The field was divided into experimental units and the statistical program Genstat (2012) was used for statistical data analysis under probability level of 0.05 to compare treatments means. The experiment consisted five irrigation treatments: T1 (100 wastewater), T2 (75% wastewater +25% river water), T3 (50% waste water + 50% river water), T4 (25% wastewater + 75% river water) and T5 (100% river water). Irrigation with treated wastewater and binary irrigation had significant effects on soil bulk density at probability level 0.05 for three depths, soil bulk density decreased with increasing of irrigation with treated wastewater rate, and it decreased with increasing of river water irrigation rate and higher increment was in T5 (100% river water only). Irrigation with treated wastewater and dual irrigation had non-significant effects on soil bulk density below probability level 0.05 for three depths, whereas soil bulk density decreased with increase of irrigation rate with treated wastewater, and it decrease with increase of river water irrigation rate and most increase in fifth treatment (100% river water only). Total porosity increased with increasing of mixing rate with treated wastewater and binary irrigation in 1.90, 2.70, 6.44 and 9.07% for 0-15 cm soil depth, and 1.86, 2.73, 5.88 and 6.12 for 15-30 cm soil depth, and0.79, 1.10, 4.22, and 3.44% for 30-60 cm soil depth for 25, 50, 75, and 100% mixing rate for irrigation with treated wastewater. Rate of soil aggregation more than 20 µ for soil sample that taken from 30-15 cm soil depth for T1, T2, T3, T4, and T5 were 33.76, 28.24, 26.40, 27.44, and 24.16% respectively. Increased mixing rate with treated wastewater and river water and binary irrigation increased mean weighted diameter (MWD) for two depths 0-15 and 15-30 cm, were 3.23, 2.01, and 1.74 and 1.40 times for treatment T2 and T3 and T4 and T5 respectively, while increase for second depth (15-30 cm) were 1.62 and 1.33 and 1.25 and 1.07 times respectively, compared with T1 treatment. Infiltration rate decreased with increasing mixing rate with treated wastewater were 10.03, 22.58, 29.26 and 43.48% for treatments T3 and T4 and T2 and T1 compared with T5 treatment, respectively.