Determining Yield and Profitability of Different Corn Irrigation Strategies

The number of pivot irrigation systems in Kentucky has increased since the 2012 drought. In general, most producers with pivot irrigation systems have developed irrigation strategies specific for their needs with the main driving factor that you should never gget behindh with the irrigation applications. Fortunately, researchers at the University of Kentucky, such as Dr. Ole Wendroth, have spent considerable effort to identify that once soil water suction reaches 85 to 93 kPa (as measured by a water mark soil moisture sensor), water should be applied with the irrigation system. However, most producers rely on a gcheck]bookh, water balance]based method to determine irrigation events. Limited replicated research trials have investigated the yield and profitability of the different corn irrigation strategies (sensor]based vs. water balance]based) in Kentucky under a pivot]type irrigation system. The objectives of this study are to determine the differences in yield and profitability among six check]book irrigation treatments, one sensor]based irrigation treatment, and one nonirrigated control treatment. The six check]book treatments will include all combinations of three different growth stages at which irrigation will begin (V6, V12, VT/R1) and two growth stages that irrigation will be terminated (3/4 milk line and R6). The sensor]based irrigation treatments will not be initiated until the soil water suction reaches 85 to 93 kPa with water mark soil moisture sensors. In order to determine whether any yield differences that are detected are due to irrigation strategy the following data will be measured: initial plant population (approximately V2 growth stage); soil moisture (as measured with water mark sensors in all experimental plots); date of emergence, V6, VT/R1, R3, R5, and R6; leaf tissue analyses each week; total amount of water applied and number of irrigation events; number of rows of kernels per ear; number of rows of kernels per ear; 100]kernel weights; final harvest plant population (immediately prior to harvest); yield; and profitability. Currently we have initiated a similar project examining the implementation of the six checkbook treatments listed above and non]irrigated control treatments. This has allowed us to understand some of the logistical challenges that may be encountered, particularly with installation of the water mark sensors. This will allow us to initiate the proposed work with as few challenges as possible. We are requesting a total of $78,571 to support this work. Funds will be used to support 100% of the PhD studentfs salary, tuition, health insurance and fringe benefits ($42,513); supplies to complete the project ($3,500); undergraduate students and field technician to assist with planting, harvest and data collection ($4,987); combine usage fees ($1,100); irrigation usage fees ($5,940); travel ($2,000) for the student to travel to Princeton to complete the proposed research and travel to a national conference to present results of this research; purchase of 20 water mark sensors ($13,000); and fees for weekly tissue sample analyses ($5,531). The water mark sensors will be a one]time investment; we are only requesting funds for 20 sensors (of the 32 total needed) because C. Knott has an additional 12 that will be incorporated into this project for no cost.