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ARS Home » Northeast Area » University Park, Pennsylvania » Pasture Systems & Watershed Management Research » Research » Publications at this Location » Publication #172571
Title: CORN YIELD RESPONSE TO NITROGEN RATE AND TIMING IN SANDY IRRIGATED SOILS

Author
item GEHL, R - KANSAS STATE UNIV
item Schmidt, John
item MADDUX, L - KANSAS STATE UNIV
item GORDON, W - KANSAS STATE UNIV

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/22/2005
Publication Date: 7/13/2005
Citation: Gehl, R.J., Schmidt, J.P., Maddux, L.D., Gordon, W.B. 2005. Corn yield response to nitrogen rate and timing in sandy irrigated soils. Agronomy Journal. 97:1230-1238.

Interpretive Summary: Nitrate contamination of groundwater drinking supplies is an environmental concern nationwide. When soil nitrate concentrations are high, and water infiltration exceeds evapotranspiration, the potential for nitrate leaching is high. Sandy soils planted to corn are particularly susceptible to this problem, because relatively high rates of nitrogen fertilizer are applied to corn. This study evaluated alternative nitrogen and water management strategies for irrigated corn on sandy soils along Kansas' major rivers. When nitrogen fertilizer was applied with multiple applications during the early part of the growing season, as opposed to a single pre-plant application, the nitrogen rate corresponding to maximum grain yield was 80 lb per acre less than the current Kansas State University recommendation. Any unused N fertilizer remaining in these soils after harvest will likely leach to the groundwater. Increasing irrigation by 25% did not increase grain yield nor change the grain yield response to nitrogen, but increased the likelihood of nitrate leaching during and after the growing season. Results from this study emphasize the importance of developing nitrogen fertilizer recommendations that are suited to specific soils, in this case sandy soils, and only applying the very minimum amount of nitrogen required to obtain maximum grain yield.

Technical Abstract: Efficient use of nitrogen (N) fertilizer for corn (Zea mays L.) production is important for maximizing economic return to the producer and minimizing NO3 leaching to groundwater, especially on irrigated sandy soils. The objective of this study was to evaluate grain yield response to alternative N and water management strategies for irrigated corn in the sandy soils along major Kansas tributaries. Field studies were conducted in 2001 and 2002 (ten site-years) at irrigated corn sites along the Republican, Kansas, and Arkansas Rivers. Nitrogen treatments were surface applied as NH4NO3 at 300 and 250 kg N ha-1 applied pre-plant; 250, 185, and 125 kg N ha-1 applied pre-plant and sidedress; and 0 kg N ha-1. At one site, the N treatments were duplicated, one for each of two irrigation treatments (IS): 1.0X (optimal) and 1.25X (25% > optimal). Grain yield was determined for all plots, and soil samples were collected in 30-cm increments at preplant and post-harvest to 240 cm. A split application of 185 kg N ha-1 was sufficient to achieve maximum corn yield at every location, and in most instance 125 kg N ha-1 was sufficient. These rates were on average 88 kg N ha-1 less than the current N recommendation for corn in Kansas, indicating that N rates could be reduced for these soils by an average of about 40% of the current N recommendation when N is split applied. The environmental risk associated with irrigated corn production on these sandy textured soils, i.e. NO3 leaching to groundwater, will be minimized only when N fertilizer and irrigation inputs do not exceed crop requirements and N fertilizer is applied to more closely match crop demand (e.g., in-season applications).