SUBSURFACE AND SURFACE MICROIRRIGATION OF CORN —SOUTHERN HIGH PLAINS

Microirrigation has the potential to minimize application losses to evaporation, field runoff, and deep percolation; improve irrigation control with smaller, frequent applications; supply nutrients to the crop as needed; and improve crop yields. This study was conducted to evaluate subsurface and surface microirrigation (SUB and TOP, respectively) application methods on crop performance. The effects of irrigation frequency, amount, and application method on crop yield, yield components, water use, and water use efficiency of corn (Zea mays L., cv. PIO 3245) were investigated at Bushland, Texas, on a slowly permeable soil [Pullman clay loam (fine, mixed, thermic Torrertic Paleustoll)] in a semi-arid environment in 1993 and 1994. Irrigation frequencies were once a day and once a week; irrigation levels varied from dryland (no post emergence irrigation) to full crop water use replenishment; and application methods were on the soil surface (TOP) and 0.3 m below the surface (SUB) with emitters spaced 0.45 m apart and drip lines spaced 1.5 m apart. Irrigation frequency and application method did not affect crop yields; however, deficit irrigation affected crop yields by reducing the seed mass and the seed number. On the clay loam soil at Bushland, irrigation frequency and application method are less critical than proper irrigation management for microirrigation systems to avoid water deficits that have a larger affect on corn yields.