BANDING NITROGEN-FERTILIZER INFLUENCE ON INORGANIC NITROGEN DISTRIBUTION

Banding nitrogen (N) fertilizer increases inorganic N variability in a reas between the corn rows for one or two years. Fertilizer recommenda tions may be improved by developing sampling systems that account for this variability. If soil samples are routinely taken from one locatio n relative to another, then fertilizer recommendations may be biased, The objective of this study was to evaluate the impact of banding N fe rtilizer on N distribution in soil. Urea ammonium nitrate was applied to a Brandt silty clay loam (Fine-silty, mixed Udic Haploboroll) at th e six leaf growth stage in 1992. Soil samples were collected from grid points (0, 8, 22, and >35 cm from fertilizer band) between the corn ( Zea mays L.) rows in the fall of 1992: Soil samples were analyzed for inorganic N. In unfertilized plots, inorganic N distribution at all of the sampling locations followed lognormal distributions. However, in band fertilized plots inorganic N distributions were influenced by sam pling location. Inorganic N estimated from samples collected 22 cm fro m the band underestimated residual N by 30 to 40%. Inorganic N was est imated correctly when samples were collected 8 cm from the band, while it was over estimated when samples were collected from the band