Determination of Irrigation Lengths in Vertisol Soils Using the Two-Point Infiltration Method and Kostiakov-Lewis Equation

Abstract

Vertisol soils, which cover large lands in irrigated areas in Turkey and the world, swell when wet and form deep cracks when dry. These properties of Vertisol soils cause a significant decrease in irrigation efficiency when irrigating with surface irrigation methods, thus causing water insufficiency and drainage problems. If appropriate irrigation time, flow rate and furrow-border lengths are used, water application efficiency can be increased in these soils. For this purpose, two-point infiltration tests were carried out using 120 m long, 0.5-0.6% slopping furrows. A constant water level orifice was used to keep the flow rate unchanged during the tests. Water advanced and recession times were observed and recorded at stations created at 20 m intervals. Before and after the test, the cross-sectional area of the furrow was measured with a rill-meter. By evaluating the obtained data, the Kostiakov-Lewis infiltration equation, which is expressed as Z = 0.00822 τ 0.27695 + 0.00048 τ equation, was obtained. With the determined equation, the optimal irrigation length was estimated to be approximately 85 m for 90% water application efficiency and 115 m for 80% water application efficiency, using the advance and recession curves.