|Renier, Robert -|
|Yost, Matt -|
|Coulter, Jeff -|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: June 30, 2012
Publication Date: September 17, 2012
Citation: Renier, R., Yost, M., Russelle, M.P., Coulter, J. 2012. Evaluating the accuracy of the presidedress soil nitrogen test when manure is applied during the rotation from alfalfa to corn [abstract]. Proceedings of the 30th Brazilian Meeting of Soil Fertility and Plant Nutrition Conference, September 17-21, 2012, Maceio, Alagoas, Brazil. Technical Abstract: Alfalfa has a great capacity to fix nitrogen (N), and it increases the amount of soil N available for the next crop. However, prediction of fertilizer requirement for corn after alfalfa is complicated because N release from organic sources varies with soil temperature and moisture. Furthermore, many producers apply manure to the terminated alfalfa field, which can increase or even decrease the amount of N available during the next growing season. The Pre-Sidedress Nitrogen Test (PSNT) provides early-season information on the amount of N mineralized before the corn crop enters the phase of rapid N accumulation. The objective of this study was to evaluate the accuracy of the PSNT in corn after alfalfa when manure was applied during fall alfalfa termination. Experiments were established in a randomized complete block design with four replications on 10 farms in Minnesota. Treatments consisted of control plots (no fertilizer N) and 45 kg N/ha applied as a sidedressing. Soil nitrate concentration was determined on samples of composited soil cores from the upper 30 cm in each plot. Corn grain yield was determined from hand-harvested samples taken after physiological maturity. Corn yield was not improved by sidedressed fertilizer N except at two of the 10 sites, which produced 1.5 and 2.4 Mg/ha more yield with 45 kg N/ha than with no fertilizer N. However, the PSNT correctly predicted the response or non-response of grain yield to sidedressed fertilizer N at only 4 of 10 farms. The PSNT did not provide reliable predictions of fertilizer N requirement in fields of first-year corn after alfalfa with additional manure N.