BANDING NITROGEN-FERTILIZER INFLUENCE ON INORGANIC NITROGEN DISTRIBUTION

Banding nitrogen (N) fertilizer increases inorganic N variability in areas between the corn rows for one or two years. Fertilizer recommendations may be improved by developing sampling systems that account for this variability. If soil samples are routinely taken from one location relative to another, then fertilizer recommendations may be biased, The objective of this study was to evaluate the impact of banding N fertilizer on N distribution in soil. Urea ammonium nitrate was applied to a Brandt silty clay loam (Fine-silty, mixed Udic Haploboroll) at the 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 sampling location. Inorganic N estimated from samples collected 22 cm from the band underestimated residual N by 30 to 40%. Inorganic N was estimated correctly when samples were collected 8 cm from the band, while it was over estimated when samples were collected from the band