INFLUENCE OF VERTICAL SAND COLUMN AND SUPPLEMENTAL IRRIGATION ON BARLEY YIELD IN ARID SOILS AFFECTED BY SURFACE CRUST

A field experiment was conducted during the 1996/1997 season at the Un iversity of Jordan Research Station near Al-Muwaqqar village to invest igate the effects of sand columns, sand column spacing, soil ridges, a nd supplemental irrigation on soil water storage, redistribution, and barley yields. The experimental site represents a typical Jordanian ar id environmental soil suffering from surface crust formation overlayin g impermeable material. In the 600-mm-depth soil profile, soil water s torage was improved significantly by 59%, 45%, and 38% in the l-m, 2-m , and 3-m sand column spacing treatments, respectively, compared with soil water storage in the control treatment (no sand columns). Sand co lumns increased the moisture stored in all four soil layers (0-150, 15 0-300, 300-450, and 450-600 mm). Moisture stored in the 450-600 mm soi l layer increased significantly by about 188%, 147%, 88%, and 29% in t he I-In, 2-m, 3-m, and 4-m sand column spacing treatments, respectivel y, compared with moisture stored in the same soil layer of the control treatment. Increasing soil water storage also increased barley consum ptive use significantly from 130 mm in the control treatment to an ave rage of about 185 mm in sand column treatments. Without supplemental i rrigation, barley grain and straw yields were negligible and almost ze ro. Barley yields in the control treatment, with 167 mm supplemental i rrigation were low, being 0.19 ton/ha and 1.09 ton/ha of barley grain and straw, respectively. Sand columns increased bar ley grain and stra w yields significantly compared with the control treatment to a maximu m of 0.68 ton/ha and 3.97 ton/ha, respectively, with the l-m sand colu mn spacing. Soil ridges perpendicular to the land slope had no signifi cant effect on increasing soil water storage due to lateral runoff and loss along the ridge. In general, sand col columns minimize surface r unoff and evaporation by allowing water to infiltration through the st rong surface crust. Sand columns act as a sink for surface water, enha nce subsurface lateral water movement, and reduce the possibility of s urface crust formation in the vicinity of the sand column opening by p reventing surface pending.