Submitted to: American Chemical Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 8/30/2001
Publication Date: 8/30/2001
Citation: OLNESS, A.E., LOPEZ, D., SWEENEY, C., MATTSON, N., CORDES, J., VOORHEES, W.B. TAILORING FERTILIZER NITROGEN APPLICATIONS TO CROP NEEDS. AMERICAN CHEMICAL SOCIETY. 2001. ABSTRACT PAPER NUMBER 125. Interpretive Summary:
Technical Abstract: Nitrogen use efficiency is affected by crop uptake potential, natural microbial N mineralization, applied fertilizer N, and climatic events. Plant uptake of N is well correlated with soil nitrate-N in the upper 60 cm of the profile. When concentrations are > 20 ug g**-1, maize yields are unaffected by additions of N fertilizer. Nitrogen mineralization is variable and largely determined by soil aeration. Relative soil aeration i determined by soil clay content, soil bulk density, and rainfall. In addition, soil pH and soil temperature directly affect microbial activity. Soil aeration, pH, and temperature are described by the General Energy Model for Limited Systems, the mathematical engine of the N-Fertilizer Decision Aid. By determining nitrate-N in the profile and monitoring climatic conditions, the rate of soil nitrate-N formation is determined and appropriate additions of N fertilizer are made. Use of this approach results in a measurable improvement in N fertilizer use efficiency.