Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 27, 1998
Publication Date: N/A
Interpretive Summary: The Management Systems Evaluation Area (MSEA) program was established to identify and evaluate agricultural management systems that can protect water quality in the Midwest. Our objective within this program was to evaluate the effects of single and split nitrogen fertilizer application strategies on subsurface drainage water quality and nitrogen uptake by corn in northeast Iowa. For the single application, 110 kg N/ha were applied before planting corn. The split application consisted of 30 kg N/ha applied before planting with additional nitrogen applied based on a soil nitrate test taken 4 to 6 weeks after planting. Corn yields from research plots with split applied nitrogen fertilizer were equal to or greater than yields from plots that received single, pre-plant fertilizer applications. Split applying fertilizer also decreased the amount of nitrate-nitrogen lost through subsurface drains when corn was seeded directly into soybean residue (no-till). Our results indicate that combining no-tillage and split nitrogen fertilizer application management can have positive environmental benefits while maintaining or increasing corn yield.
Technical Abstract: Demonstrating positive environmental benefits of alternative N management strategies, without adversely affecting crop growth or yield, was a major goal for the Midwest Management Systems Evaluation Area (MSEA) program. Our project objectives within this program were to quantify the effects of split- and single-N fertilization strategies on NO3-N concentration and loss in subsurface drain effluent and N accumulation and yield of corn (Zea mays L.) and soybean [Glycine max (L.) Merr.]. The study was conducted on glacial till soils in northeast Iowa from 1993 through 1995 using no-till and chisel plow tillage treatments. One-third of the 2611 effluent samples had NO3-N concentrations greater than 10 mg/L. Split applying fertilizer N using the pre-sidedress soil nitrate test(PSNT)increased corn yield for both tillage treatments in the extremely wet 1993 without increasing NO3-N loss in drain effluent. When fertilizer N was applied based on the PSNT, no-till and chisel treatments had similar NO3-N losses and concentrations in drain effluent. Average NO3-N concentrations in drain effluent were not increased when larger amounts of fertilizer were applied based on PSNT. However, prior crop and tillage practices and differences in drain flow volume caused significantly differences in NO3-N losses and concentrations. These results suggest that spatial differences in flow volume are a major factor determining NO3-N loss in drainage effluent. Significant differences in drainage water quality and crop uptake suggest that combining no-tillage practices with a split N fertilizer management strategies can have positive environmental benefits without reducing corn yield.