2008 Joint Annual Meeting (5-9 Oct. 2008): Managing Irrigated Corn with Diminished Well Capacity

73-5 Managing Irrigated Corn with Diminished Well Capacity



Wednesday, 8 October 2008: 9:05 AM
George R. Brown Convention Center, General Assembly Theater Hall C
Alan Schlegel, Southwest Research Extension Center, Kansas State University, Southwest Res. Ext. Center, 1474 State Highway 96, Tribune, KS 67879 and Loyd Stone, Dep. of Agronomy, Kansas State University, 2004 Throckmorton Hall, Manhattan, KS 66506
Limited irrigation research was initiated under sprinkler irrigation in western Kansas at the Tribune Unit, Southwest Research-Extension Center in the spring of 2006. The objectives were to determine optimal plant population and grain yield benefit for corn from preplant irrigation when in-season well capacity is diminished because of depletion of the Ogallala Aquifer. The study was a factorial design of preplant irrigation (0 and 75 mm), well capacities (2.5, 3.8, and 5 mm day-1 capacity), and plant population (55,000, 68,000, and 80,000 plants ha-1). The irrigation treatments were whole plots and the plant populations were subplots. Preplant irrigation increased grain yields an average of 0.8 Mg ha-1. Grain yields increased 15% when well capacity was increased from 2.5 to 5.0 mm day-1. The yield increase was due to increased seed weight and number of seeds ear-1. Preplant irrigation increased the number of seeds ear-1 but had little impact on seed weight. The optimum plant population varied with irrigation level. With the lowest well capacity and without preplant irrigation, a plant population of 55,000 plants ha-1 was adequate. However, if preplant irrigation was applied, then a higher plant population (68,000 plants ha-1) increased yields even at the lowest well capacity. When well capacity increased to 3.8 mm day-1, then 68,000 plants ha-1 were required to optimize yields without preplant irrigation and 80,000 plants ha-1 with preplant irrigation. With a well capacity of 5 mm day-1, a plant population of 80,000 plants ha-1 provided greater yields with or without preplant irrigation. Preplant irrigation is a viable practice when in-season well capacity cannot fully meet crop needs. Plant populations should be adjusted for irrigation level considering both well capacity and preplant irrigation.