Evaluation of Soil Nitrogen Tests for Predicting Corn Nitrogen Needs. (5382)
Authors:
J.T. Osterhaus* - Univ. of Wisconsin L.G. Bundy - Univ. of Wisconsin
Abstract:
The use of soil tests to more accurately predict the nitrogen (N) need of corn (Zea mays L.) could reduce costs to producers and limit environmental impacts
associated with N losses from cropland. Soil samples (0-30cm depth) collected from more than twenty N response experiments in Wisconsin over the past two decades were analyzed using several soil N tests including the pre-plant nitrate test (PPNT), the pre-sidedress nitrate test (PSNT), and the Illinois soil nitrogen test (INST). Experiments included a range of soils, management histories, and observed economic optimum nitrogen rates (EONR). Regression analysis was used to
compare N test results with the EONR identified in each of the experiments. These relationships were used to evaluate the ability of these tests to predict crop N need.
Results from these tests show that PPNT and PSNT were more strongly correlated to EONR than the INST results. INST values were not well correlated with
observed EONR. However, the INST results were strongly correlated with soil organic matter content (r2=0.75) suggesting that the INST measures a constant fraction of soil organic N rather than a variable, readily available N pool.
Speaker Information: Jeffrey Osterhaus, Univ. of Wisconsin, Department of Soil Science 1525 Observatory Drive, Madison, WI 53706; Phone: 608-263-3878; E-mail:
Session Information: Tuesday, November 2, 2004, 1:00 PM-5:00 PM Presentation Start: 1:00 PM (Poster Board Number: 2650)
Keywords: Illinois soil nitrogen test; amino sugars; preplant nitrate test; presidedress nitrate test
