|Doran, J - UNIV NEBRASKA|
|Ferguson, R - UNIV OF NEBRASKA|
Submitted to: Meeting Abstract
Publication Type: Proceedings
Publication Acceptance Date: October 15, 2001
Publication Date: N/A
Technical Abstract: This report details the second year of a study to determine whether differences in electromagnetic (EM) soil conductivity and available N levels during a corn growing season were linked to nutrient transformation and uptake. The study site has been treated with manure and compost for eight years at rates matching either the phosphorus or the nitrogen requirements of silage corn (Zea mays L.). The plot was split for sub- treatments of a rye (Secale cereale L.) winter cover crop and no cover crop. Soil conductivity maps of the cornfield were generated over time using a global positioning system (GPS) and EM induction methods. Based on analysis of soil cores (0-30 cm), NO3 contributed between 8-58% of total soil electrical conductivity (EC 1:1) of the samples and accounted for much of the variability in conductivity during the growing season. Nitrogen mineralization was estimated by assuming that biological activity doubles with each 10C increase in temperature and increases linearly with soil water content to a maximum at 60% water-filled pore space. Nitrate usage was estimated with a crop uptake model. The utility of the EM method for assessing soil condition and the seasonal dynamics of nitrate in the research cornfield was supported by soil chemical analyses and soil and crop models.