Yield Response of Potatoes to Surface and Subsurface Drip Irrigation

Expansions in irrigated areas and population growth have led to groundwater depletion, lowering of water tables and seawater intrusion in coastal areas of the Sultanate of Oman. Modern irrigation systems were introduced as part of an integrated conservation-augmentation effort to conserve water resources. The effects of drip irrigation on potato yields were investigated in this study. One or two plants per emitter have been irrigated through surface and subsurface water applications of 4 and 8 mm / day. Throughout the experiments, soil water content and salinity changes were monitored with time at two depths using tensiometers and a special Sigma Probe, respectively. The Statistica program was used to draw contour lines indicating salt redistributions in a soil profile grid. Subsurface applications of water conserved soil water and produced significantly higher ECSW values near the soil surface away from the tuber and roots, whereas surface applications produced higher ECSW values at greater depths. Elevated number of tubers and reduced total weight for surface irrigation methods resulted in a significantly higher weight per tuber (marketable tubers) and water use efficiency for the subsurface irrigation methods. Higher water application rates resulted in higher tuber numbers and significantly higher total yields with significantly better quality (marketable) tubers, whereas lower water application rates gave significantly higher water use efficiencies by virtue of the limited amounts of water applied. Two plants per emitter resulted in significantly higher number of tubers, total yields and water use efficiencies with subsurface irrigations. However generous subsurface supply of water resulted in poor development of tubers and water use efficiencies with one plant per emitter.