In-situ Soil Nitrogen Mineralization in response to Nitrogen management for Corn and Soybean in poorly drained Soils with and without Tile-Drainage

Fabián G. Fernández1, Karina Fabrizzi1

1 University of Minnesota, 1991 Upper Buford Circle, St Paul, MN, 55801, http://www.swac.umn.edu/, [email protected]  

Abstract

Greater understanding of N mineralization is needed to improve N rate guidelines and fertilizer efficiency. Our objective was to quantify N mineralization throughout the growing season when corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] are grown under different N and soil drainage management. In-situ N mineralization incubations were conducted in drained and undrained soils with corn and soybean and different N rates over a two-year period. In the first three years of drainage installation 2.4 Mg C ha-1 yr-1 were lost. This factor combined with the effect of drainage on soil water content, N rate, and previous crop substantially influenced net mineralization and mineralization rate. However, substantial yearly differences due to moisture conditions often overshadowed the effects of these variables. Our results highlight the need to continue concerted research efforts to refine our understanding of how different factors influence the mineralization process to improve N management.