Submitted to: American Society of Agronomy Meetings
Publication Type: Abstract Only
Publication Acceptance Date: 9/15/2001
Publication Date: 11/1/2001
Citation: Balkcom, K.S., Hansen, D.J., Morris, T.F., Mallarino, A.P. 2001. Early season losses of fertilizer nitrogen from iowa cornfields. American Society of Agronomy Meetings.
Interpretive Summary: not required.
Technical Abstract: Losses of nitrogen (N) from fields planted to corn (Zea mays L.) pose long-standing economic and environmental problems. Soil and tissue tests for nitrate offer potential for reducing these problems, but it is not clear how the tools are best utilized. A novel method using these tests is described and examples of the type of information generated by this method are shown. More than 3,200 samples were collected over an 11-year period to survey N-sufficiency levels attained in fields managed by farmers. Results of the surveys were analyzed to identify the major factors affecting N-sufficiency levels attained in these fields. Analyses revealed that early season rainfall associated with losses of N were a major factor affecting sufficiency levels attained. The results help to explain why farmers usually do not give recommended fertilizer credits for N supplied by animal manures. The results also explain why delaying applications of fertilizer should be expected to increase profits for farmers while substantially reducing losses of N from cornfields. The methods used enable evaluation of management practices on farms and provides feedback needed for continuous and site-specific optimization of these practices.