Studies were conducted in a field planted to corn following corn and managed by a producer using
his normal practices. Anhydrous ammonia was injected in early April of 2004 at a rate of 105 kg N ha−1
by using an applicator with knives separated by 76 cm. Due to the unexpected applicator malfunction,
two adjacent knives accidentally applied no fertilizer and produced a non-fertilized strip that went the
length of the field. The strip could be easily identified by visual examination of plant height and color
in early June. The effects of fertilizer were not confused with planting pattern because the ammonia
was applied about 15◦ diagonal to the corn rows that were planted about one week later. In accordance
with the producer’s practice, an additional 125 kg N ha−1 was injected as a urea-ammonium-nitrate
solution (28% N) to a depth of 10 cm in bands located midway between all corn rows on June 4