IRRIGATION MANAGEMENT-PRACTICES FOR CORN PRODUCTION IN NORTH CENTRAL KANSAS

Surface water shortages plus declining groundwater reserves in many ar eas of Kansas require that farmers develop strategies to manage limite d irrigation for maximum profit. The objective of studies conducted fr om 1975-1991 was to evaluate effects of timing and number of irrigatio ns on corn (Zea mays L.) grain yield. The soil is a Crete silt loam (f ine, montmorillonitic, mesic Pachic Arguistoll) on the Irrigation Expe riment Field located in the Bostwick Irrigation District near Scandia, Kansas. Treatments varied over the years but generally included irrig ations timed from pre-tassel to 2 weeks after tasseling. Irrigations t hat were scheduled on soil water depletion levels also were included. Irrigating before tassel emergence did not improve corn grain yields a s compared with irrigation started at tasseling. Irrigating at tasseli ng and again 1 and 2 weeks later (total of three irrigations) produced yields equal to those obtained by scheduling with planned soil water depletion levels. For the period 1981-1991, one irrigation at tasselin g produced 82% of maximum yield. Two irrigations (at tasseling and 1 w eek later) produced 94% of maximum yield. Very little water was deplet ed below the 75-cm (30 in) soil depth, indicating little root activity below this depth. Maximum crop evapotranspiration rate occurred betwe en the silking and blister kernel growth stages. Acceptable corn yield s can be achieved with minimum irrigation imputs if the irrigations ar e properly timed.