SUBSURFACE AND SURFACE MICROIRRIGATION CORN - SOUTHERN HIGH-PLAINS

Microirrigation has the potential to minimize application losses to ev aporation field runoff and deep percolation; improve irrigation contro l 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) app lication methods on crop performance. The effects of irrigation freque ncy, amount, and application method on crop yield, yield components, w ater use, and water use efficiency of corn (Zea mays L., cv. PIO 3245) were investigated at Bushland, Texas, on a slowly permeable soil [Pul lman 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 em ergence irrigation) to full crop water use replenishment; and applicat ion 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 a part. Irrigation frequency and application method did not affect crop yields; however deficit irrigation affected crop yields by reducing th e seed mass and the seed number On the clay loam soil at Bushland, irr igation frequency and application method are less critical than proper irrigation management for microirrigation systems to avoid water defi cits that have a larger affect on corn yields.