Abstract

The purpose of this study was to determine the comparison of salt accumulation in soil profile and crop yields under drained and un-drained conditions. Current field conditions were used to represent poorly drained conditions where drainage system was not installed yet. Simulations were performed to illustrate well drained condition using the water management simulation model while controlling soil salinity in root zone. To put forward drainage system impacts; soil salinity and relative crop yields for well drained conditions were compared to poorly drained conditions. Soil, crop and site parameters were obtained from coordinated 40 soil sampling locations where dry bean, winter wheat and fallow crop rotations were applied. Results of the study showed that water table decreased rapidly after installing proper drainage system. Percentage of salt decreases in soil profile occurred by 24.1, 37.9 and 14.4% for wheat, bean and fallow locations respectively with adequate drainage conditions. On the drained soils, the relative yield of the winter wheat was higher by 11.2%, on the average, whereas that of bean was higher by 24.7%. Overall the net impact of yield enhancement due to drainage was about 36%. This shows the positive impact of drainage system on crop yields in this area.

Key words: Drainage, soil salinity, crop yield, water table, computer model.