Effects of Conservation Tillage Systems and Different Super Absorbent Polymer Rates on Soil Physical Properties and Water Use Efficiency in Grain Corn

A field study was conducted to evaluate the effects of conservation tillage systems and different super absorbent polymer (SAP) rates on soil physical properties, grain yield and irrigation water use efficiency at Darab Agricultural Research Station during two growth seasons. The experimental design was done as split-plot based on a randomized complete blocks with three replications. The different tillage systems were in three levels of conventional tillage, reduced tillage and no-tillage as the main plot and rates of SAP as the subplot include: 0, 80, 100, 120, 140 kg ha-1 super absorbentapplication. The results showed that the no-tillage and reduced tillage systems increased soil bulk density in the 0-10 cm soil layer by 19.3% and 9.2%, respectively, compared with the conventional tillage. The findings also revealed that the effect of different tillage systems and rates of super absorbent polymer on soil bulk density and cone index of soil in the surface soil layer were significant. The highest porosity, the lowest cone index and bulk density were seen in the application of 120 and 140 kg ha-1 super absorbent polymer. Corn yield and irrigation water use efficiency had a different reaction to the different rates of super absorbent polymer. The highest corn yield and irrigation water use efficiency was obtained at the combination of no-tillage with 120and 140 kg ha-1 super absorbent polymerapplication, although there was no significant difference between them. According to our findings and based on the crop yield and irrigation water use efficiency, the application of 120 kg ha-1 super absorbent in combination with no-tillage method were seen suitable in the south of Fars province and areas with similar climate.