Received for publication 2 Oct. 1986. Technical Contribution no. 2628 of the South Carolina Agricultural Experiment Station, Clemson Univ. We thank the Dow Chemical Co., Midland, Mich. for donating the nitrapyrin (N-Serve 24E) and Estech, Inc., Chicago, for the IBDU fertilizer and the micronutrient (Perk) used in these tests. A mention of a tademark does not constitute a guarantee or warranty of the product by the authors and does not imply its approval to the exclusion of other products that may also be suitable. The cost of publishing this paper was defrayed in part by the payment of page charges. Under postal regulations, this paper therefore must be hereby marked advertisement solely to indicate this fact.