Saturday, 15 July 2006
153-17

Soil Matric Potential under Two Moisture Levels with Surface Irrigation.

Rafael Figueroa, Antonio Gallegos, Cirilo Vazquez, Salvador Berumen, Enrique Salazar, and J. Dimas Lopez. Univ Juárez del Estado de Durango, Dom. Conocido, Venecia, Dgo., Gomez Palacio, Dgo., Mexico

Efficient use of water during irrigation is very important to achieve both water saving and higher crop productivity in regions like the Comarca Lagunera, Mexico, where water is an scarce and expensive resource. A better water use efficiency is achieved through several strategies among which is the monitoring of the level of water energy in the soil during the irrigation interval. This measurement is useful for both irrigation scheduling and irrigation application evaluation and it is considered one of the most reliable (Samani, 2003). The variable which represents the energy status of water in the soil is the matric potential (Ψm) and it was measured in this study to determine the behavior of water level in a soil irrigated with two types of surface irrigation. Matric potential readings were taken at an experimental plot where two types of surface irrigation were being evaluated. In one of them, irrigation was applied based on water deficit in the soil and measuring the water applied to the field through 0.075 m aluminum pipes, which was called “Measured irrigation”; whereas the other treatment consisted of measuring both irrigation time and water applied as the farmer uses, which was called “Conventional irrigation”. Matric potential was measured at three depths, 30, 60 and 90 cm during the irrigation interval. Average values of Ψm were contrasted using a T- Student test doing the following comparisons: between soil depths, between irrigation times (after versus before irrigation) and between irrigation methods. The level of Ψm varied with the timing of sampling (before or after irrigation). Likewise, it decreased along the irrigation interval. In regard to the difference between soil depths, the upper layer (0-30 cm) showed a lower value in comparison to the other depths (30-60 and 60-90 cm). Differences were higher in the Conventional irrigation (CI) with respect to the Measured Irrigation (MI) varying from 13.9 cbar to 37 cbar, which is equivalent to 26.6 to 84.8 % and occurred at the comparisons 60 vs 90 and 30 vs 90 cm, respectively. A highly significant difference (< 0.01) resulted when the Ψm obtained before irrigation was compared to that resulted after irrigation.

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