Document Type : Research Paper
Authors
1 Assistant Professor of Agricultural Engineering Research Department, Agriculture and Natural Resources Research and Education Center of Semnan (Shahrood), Agricultural Research, Education and Extension Organization (AREEO), Shahrood, Iran
2 Expert, Department of Agricultural Engineering Research, Agriculture and Natural Resources Research and Education Center of Semnan (Shahrood), Agricultural Research, Education and Extension Organization (AREEO), Shahrood, Iran.
Abstract
Abstract
One of the methods of optimal management of water consumption in the agricultural sector is subsurface drip irrigation. The aim of this study was to investigate the technical performance and soil salinity in the subsurface drip irrigation systems implemented in Semnan province during the years 2019 to 2020. Five systems were evaluated in Shahroud, Damghan and Semnan. For this purpose, the hydraulic characteristics of the system, soil moisture and soil salinity were investigated. In general, the results of the evaluation showed that the coefficient of flow variations (Vqs) varied from 4 to 8 percent, the statistical uniformity coefficient (Us) varied from 85 to 90.7 percent, and the emitter discharge coefficient of variation (Vpf) varied from 0.09 to 0.15. The hydraulic performance of the systems was relatively good. The evaluation results showed, the pressure at the end of the laterals was less than necessary in some parts, but the use of pressure compensating emitters adjusted the flow in these parts. In the studied orchards, the installation depth of the laterals was non-uniform and between 15 and 45 cm. The amount of moisture increased from the soil surface to the depth. Examination of salinity profile of soil saturated extract showed that with increasing horizontal distance from the lateral, the amount of salinity has increased but with increasing depth it has decreased. In the installation depth of 30 and 40 cm salinity was highest at 0-30 and 30-60 cm depths. The reason for the increase in salinity in this area was the decrease in soil moisture due to the capillary rise of moisture and its evaporation from the soil surface and faster absorption of moisture by the roots. The most important factors to improve the performance of systems are: proper implementation of systems and providing the necessary pressure in the manifolds and laterals, soil leaching in winter with heavy flood irrigation and installation of the laterals evenly at the appropriate depth.
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