Effectiveness of Nitrapyrin with Surface‐Applied Fertilizer Nitrogen in No‐Tillage Corn¹

Abstract

Abstract Nitrapyrin [2‐chloro‐6‐(trichloromethyl)pyridine] has been shown to slow the nitrification process by selectively inhibiting nitrifying soil bacteria, thus keeping N less susceptible to losses by leaching and denitrification. Since nitrapyrin is volatile, the manufacturer recommends incorporation into the soil immediately after applying. However, in no‐tillage production of corn ( Zea mays L.), fertilizers usually are not incorporated. The objective of this study was to determine the effectiveness of nitrapyrin sprayed onto granular ammonium nitrate and urea fertilizers which were then applied to the soil surface for no‐tillage corn. Eight field experiments were conducted at four locations in Kentucky over a 5‐year period on soils that are usually wet during the spring. Nitrogen fertilizers were applied at rates ranging from 0 to 180 kg/ha of N. The rate of nitrapyrin application was 0.56 kg/ha. Nitrapyrin resulted in increased corn yields in most cases where N fertilizers were applied at yield‐limiting rates. This study indicated that nitrapyrin functions effectively for no‐tillage corn when applied directly to N fertilizer granules and broadcast on the soil surface. It was thought that volatilization of nitrapyrin was not great enough to render it ineffective when concentrated in the soil with the NH 4 + . Grain yield response in notillage corn may be expected when environmental conditions would cause severe leaching or denitrification losses and plant growth limitation without nitrapyrin.