AbstractVery few experiments have been conducted to evaluate N‐Serve [2‐chloro‐6‐(trichloromethyl) pyridine] formulated with N fertilizer for sugarcane (Saccharum officirarum L.). N‐Serve when fomulated with N‐fertilizer increased sugarcane yields in the Philippines and in Louisiana but failed to do so in Puerto Rico and in Mauritius. In view of the relatively few experiments conducted with N‐Serve for sugarcane and the conflicting nature of the results, a pot experiment in drums and a field experiment were conducted to study the effect of N‐Serve formulated with solid ammonium sulfate (AS) on sugarcane (‘HJ 5741’) yield, leaf N content, tillering, and on soil N. In the pot experiment two soils, a clayey loam (Typic Tropaqualfs) and a loamy sand (Aquoxic Tropudults) were used combined with a high and low irrigation treatment. There were two rates of AS with and without N‐Serve. A control treatment was also included. N‐Serve was applied at 2.5% of the weight of AS. In the field experiment on a sandy clay (Typic Tropaqualfs) there were three rates of AS with and without N‐Serve. A control treatment was also included. N‐Serve was applied at a flat rate of 24 liters/ha.In the pot experiment N‐Serve increased the yield of sugarcane and leaf N‐content at the low rate of N application. However, N‐Serve reduced yields in the loamy sand soil at both rates of N under low irrigation. N‐Serve was effective in inhibiting nitrification at least up to 6 weeks in all four combinations but it was less effective in the loamy sand soil under high irrigation. High percentage of N in the leaf of the N‐Serve treatments reflected the higher efficiency of N fertilizer with N‐Serve. In the field experiment N at 103 kg/ha with N‐Serve gave yields almost equal to 206 kg/ha without N‐Serve. Nitrification was inhibited up to 12 weeks at N‐Serve application with low rate of N in the field. As in the drum experiment, the efficiency of the N‐fertilizer (as reflected by higher percentage N in the leaf) was improved with N‐Serve applications, especially with lower rates of N.