Submitted to: Crop Management at www.cropmanagement.org
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 30, 2012
Publication Date: February 9, 2012
Repository URL: http://Online Crop Management doi:10.1094/CM-2012-0127-01-RS.
Citation: Sorensen, R.B., Lamb, M.C., Butts, C.L., Nuti, R.C. 2012. Corn Yield and Economic Return with Nitrogen Applied Through Drip Tubing. Crop Management 11. doi:10.1094/CM-2012-0127-01-RS. Interpretive Summary: Subsurface drip irrigation (SSDI) has the potential to provide consistently high yields with non-uniform precipitation while conserving soil, water, and energy. Drip systems have the capability of frequently supplying water to the root zone while reducing the risk of cyclic water stress that is typical of other irrigation systems or nonirrigated production. Previous economic research reported that subsurface drip systems (SSDI) would be more profitable for small areas (<50 ac) because of its lower per acre investment and lower pumping costs compared to fixed or towable center-pivot system. These SSDI systems are adaptable to variations of field shape making them an important consideration in the Southeast. Drip irrigation would also be preferred in irregularly shaped fields where a full circle irrigation system cannot be installed. Nitrogen is one nutrient that most often limits corn yield. Seasonal uptake and nutrition needs of corn in the southeast indicate no increase of yield when nitrogen was applied over 200 lbs N/ac. Current recommendations in Georgia specify that nitrogen should be applied at 40 to 60 lbs N/ac before planting with the rest applied in split application of 30 to 60 lbs N per application in a bi-weekly basis until total has been applied usually in three to five applications with a total of about 200 lbs N/ac per year. The objectives of this research were to: 1) determine the yield response of corn to either SSDI or SDI, 2) determine yield response to various amounts of nitrogen applied through the drip system in conjunction with dry surface applied nitrogen, and 3) determine partial net returns for the two irrigation system types and nitrogen treatments when growing corn. This project was conducted for two years (2006 and 2007). A subsurface (SSDI) and surface (SDI) drip irrigation system was installed in the spring of 2000. The SSDI system had drip laterals buried 12 in deep and spaced at 3 ft intervals with emitters spaced at 12 in. Water flow rate was 0.44 gal/min per 100 ft of drip tubing. The SDI system had 8 mil wall thickness with emitters spaced at 12 in. The laterals were spaced at 6 ft intervals in alternate row middles. Emitter flow rate was 0.25 gal/min per 100 ft of tubing. Land preparation was the same in all zones where they were disk harrowed two times followed by an experimental bedder (USDA-ARS-National Peanut Research Laboratory, Dawson, GA) used to make 6 ft raised beds with two crop rows spaced 3 ft apart. Corn was planted in a single row orientation with a 3 ft row spacing at about 5.5 in/seed spacing for about 32,000 seeds/ac. The irrigation system was automated using an electronic datalogger connected to an onsite weather station. The datalogger calculated irrigation runtimes and controlled electronic solenoid valves for irrigation. Nitrogen was applied in three split applications at the same time period each year. This research indicates there is no yield differences with the use of either SSDI or SDI system provided nitrogen levels are the same. Corn yields were reduced when nitrogen rates were lower than recommended irrespective of the irrigation system. Applications of nitrogen through SSDI and SDI showed that three split applications totaling 200 lbs N/ac had the highest yields and were similar to yields and nitrogen levels described with overhead irrigation systems. Nitrogen rates below 200 lbs N/ac had lower yields while nitrogen application over 200 lbs N/ac did not increase in yield. This implies that nitrogen recommendations for overhead and drip irrigation systems are similar. There did not seem to be difference in yield as to whether nitrogen was applied through drip tubing or applied to the soil surface. More research would be needed to identify more precise timing of nitrogen applied (split applications) with drip irrigation. The best economic return occurr
Technical Abstract: A two year project was established to determine corn (Zea mays, L) yield response to subsurface (SSDI) and surface (SDI) drip irrigation systems at various nitrogen fertilizer rates. Nitrogen was applied through the drip system at two nitrogen levels in three split applications. Supplemental dry N fertilizer was applied on the soil surface at three nitrogen rates. Corn grain yield, test weight, nitrogen efficiency, gross and net revenue were determined for each treatment. Rainfall received during the growing season was 10.6 and 16.0 inches for 2006 and 2007, respectively. Irrigation applied during the growing season was 14.8 and 8.5 inches during 2006 and 2007, respectively. Yield was greater in 2006 (190 bu/ac) compared with 2007 (167 bu/ac). There was no yield difference between SSDI and SDI at associated nitrogen treatments. Corn yields were lower at a base of 100 lbs N/ac (177 lbs/ac) compared with a base of 200 lbs N/ac (206 bu/ac). Corn yield did not increase once 200 lbs N/ac had been applied either with drip or surface applications. Nitrogen efficiency was greater at lower nitrogen rates and decreased as nitrogen rates increased. Best yield occurred at 200 lbs N/ac with average net revenue of $706/ac.