EFFECT OF SOIL SURFACE TREATMENTS ON RUNOFF AND WHEAT YIELDS UNDER IRRIGATION

In arid and semi-arid regions, where soil structure is unstable, surface runoff due to seal formation reduces irrigation water use efficiency. This study was conducted to determine the efficiency of surface treatments in reducing runoff and increasing wheat crop productivity. Surface runoff from wheat plots on a non-sodic, silty clay loam soil (Rhodudalf silty clay loam), sprinkler irrigated with a good quality irrigation water, was collected using flumes and collection boxes. Percentages of runoff were 36.1% of the total irrigation during the growing season for the control (Ct), 12.8% for phosphogypsum (PG), 1.4% for polyacrylamide plus PG (PAM), and 1.1% for pitting plus PG (Pt) treatments. The mulching effect of the growing canopy did not reduce runoff during consecutive irrigations as the season progressed. Water content in the profile was correlated with the amount of water that infiltrated into the soil. The crop biomass production in the Pt and PAM treatments was significantly higher than the PG and Ct treatments (8.81 and 7.91 vs. 6.41 and 5.47 Mg ha-1, respectively). The Pt and PAM treatments also gave significantly higher grain yield (3.66 and 3.02 vs. 2.25 and 2.12 Mg ha-1, respectively). The Pt, PAM, and PG treatments resulted in significantly higher irrigation water use efficiency (IWUE) than the Ct. The PAM is the least known treatment and is given special attention in this study. In regions where water is scarce and costly, improving the efficiency of irrigation by tillage or soil ameliorants should be considered.