High nitrogen fertilizer prices—again
Date
Authors
Major Professor
Advisor
Committee Member
Journal Title
Journal ISSN
Volume Title
Publisher
Authors
Research Projects
Organizational Units
Journal Issue
Is Version Of
Versions
Series
Department
Abstract
Corn N fertilization. I am often asked what N rate should be applied for corn production. I hesitate to give too simple of an answer, but actually a straightforward rate of 125 lb N/acre for corn following soybean (SC) and 175 lb N/acre for corn following corn (CC) (continuous, second-, or third-year) with good N management works well. If you have followed Iowa State University Extension publications regarding N management over the years, these rates are in the middle of suggested rate ranges provided since at least 1979 (100–150 lb N/acre for SC and 150–200 lb N/acre for CC). An analysis of recent data from many N rate trials conducted in Iowa since 1991 indicates these “straightforward” rates are still correct. Figure 1 shows the economic net return to N for SC and CC at four different price ratios of N price:corn grain price ($/lb N:$/bu corn grain). For the figure, the corn price was held constant at $2.20/bu and N prices were varied from $0.11, 0.22, 0.33, and 0.44 per lb N. These give price ratios of 0.05, 0.10, 0.15, and 0.20, respectively at the four N prices. The point of maximum return to N (MRTN) is the N rate where the greatest economic net return to N occurs. This is indicated by the solid symbols on each price ratio line. As you can see, at the 0.10 price ratio the maximum return occurs at 123 lb N/acre for SC and 174 lb N/acre for CC, at the middle of currently suggested N rate ranges.