Study on effect of increasing ratio of cultivated to uncultivated strip width on root zone salinity reduction in Dry Drainage

High volume of drained water and low quality are two major challenges of subsurface drainage systems’ operators. Dry Drainage (DD) can solve these problems with low cost and environmental considerations where the irrigation water is much less than the amount to satisfy the extent of the available land. Results of previous studies showed that by DD, we can control salinity of root zone with leave half of land. In this study, ratio of cultivated strip width to uncultivated strip width was investigated as a major effective parameter on DD efficiency. This study was conducted with two lysimeters at research field located in University of Teharn, Abouraihan College on 2015, by considering of two different ratios of cultivated strip width to uncultivated strip width (1:1 and 2:1). Sport grass was used in cultivated strip as reference crop. Soil texture was Loam and irrigation water salinity was 3 dS/m. Irrigation water was produced by mixing of tap water and saline water of Qazvin’s Marshland. Results showed that, salt balance in root zone can be maintained by increasing amount of cultivated strip width. Though ratio of 2:1 will be accepted but we should consider that by increasing this ratio, amount of accumulated salt at uncultivated strip will be increased, therefore we need better management to remove salt in this condition. Also results of each lysimeters showed independently that, Dry Drainage has ability of transporting salt from cultivated areas to uncultivated areas and after a while, root zone salt concentration will be balanced. Soil salinity of cultivated strip did not exceed 6 dS/m at end of test; nearly twice the salinity of the irrigation water.