IRRIGATION WATER MANAGEMENT VIA DETECTING ACTIVE ROOTING ZONE USING NEUTRON SCATTERING TECHNIQUE

Abstract

The aim of the study was to schedule irrigation depending on the active root depth, to object a good water irrigation management and to minimize water loss by deep percolation. To achieve this aim, neutron moisture meter was used to detect soil water content after and before next irrigation, to determine soil moisture depletion, which happened during the irrigation interval and soil moisture retention curve model for different soil depths, van Genuchten model for water retention after estimating the equation parameters , m, and n. Therefore, it was possible to predict soil moisture tension at different moisture content after and before irrigation, where it was possible to determine total hydraulic potential which was equal to soil matric suction plus gravitational potential. Total hydraulic potential through the soil profile up to active root depth it was possible to determine the loss of soil water by evaporation, water uptake by plant roots and deep percolation (under active root depth). Three water treatments (T1, T2, and T3), (100%, 80% and 60% from the active root depth) were applied, which was estimated according to the quantity of water depleted from field capacity to a certain depth. Chickpea plant was planted under trickle irrigation system, access tubes were installed close to the distance of 12.5cm around the dripper. These access tubes were used for neutron scattering meter. The results can summarized in these points - The use of neutron moisture meter was one of the simplest methods to determine soil moisture, matric potential and hydraulic potential to save time and effort. - This technique helped to study the behavior of irrigation water in the soil profile and also helped control irrigation water.