ABSTRACT
Nitrogen (N) management can elicit changes in soil organic matter levels by affecting crop productivity and the return of unharvested residues to the soil. Field research on urea and ammonium nitrate management was initiated in 1960 at the Southwest Experiment Station (SWES), Lamberton Minnesota, to evaluate the effects of N form, placement, rate, and time of application on corn yields. Field research on urea and ammonium nitrate management was initiated in 1960 at the SWES, Lamberton Minnesota, to evaluate the effects of N form, placement, rate, and time of application on corn yields. The field study is located in southwest Minnesota on the University of Minnesota, Southwest Experiment Station near Lamberton. Native vegetation was tall-grass prairie and the soil is currently classified as Normania loam with minor inclusions of Webster clay loam. Several studies have indicated a linear relationship between changes in soil C and the amount of unharvested carbon inputs.
