Submitted to: Agronomy Abstracts
Publication Type: Abstract only
Publication Acceptance Date: 9/1/2004
Publication Date: 11/1/2004
Citation: Wilhelm, W.W., Ruwe, K.J., Johnson, B.E., Mounsey, K.L. 2004. Assessing the stalk nitrate test as an n-management tool for hybrid seed production. Agronomy Abstracts #4178. Interpretive Summary:
Technical Abstract: The end-of-season stalk NO3 test is a tool useful for determining if yield-limiting (less than 700 mg NO3 kg stalk-1) or excessive (greater than 2000 mg NO3 kg stalk-1) N was applied to hybrid corn (Zea mays L.). Growers attempt to maximize production in seed production fields by applying N fertilizer at rates that do not limit yield. However, application of excessive N-fertilizer may degrade groundwater quality. The experiment was conducted to evaluate the applicability of the stalk NO3 test for N management for hybrid seed production and ascertain if critical values for hybrids are appropriate for inbred lines. At physiological maturity, yield and nitrate concentration of the lower portion of stalks was determined for three inbred lines grown at six N-fertilizer application rates in rotation with soybean [Glycine max (L.) Merr.] or in continuous corn production over three years. Inbred and fertilizer-N application, but not their interaction, were significant sources of variation for both grain yield and stalk NO3 concentration with continuous corn production. Variation among inbred lines and years made confirmation of critical values for inbred lines difficult. However, in all cases, the critical values for excessive N application in hybrids was well within the plateau portion of the yield response curve for the inbred lines suggesting that a lower critical value maybe appropriate.