Evaluation of Commercial Additives Used with Granular Urea for Nitrogen Conservation

Abstract

Core Ideas Urease and nitrification inhibitors can reduce N loss from granular urea. Agrotain Ultra functioned as a urease inhibitor, Nutrisphere‐N, and NZone did not. Agrotain Ultra reduced ammonia volatilization, Nutrisphere‐N, and NZone had little effect. SuperU and Instinct inhibited nitrification, Nutrisphere‐N, and NZone did not. ABSTRACTUrea is subject to loss by ammonia volatilization, and, after nitrification, by leaching and denitrification. This study evaluated commercial products marketed as fertilizer additives for granular urea for the purpose of reducing N loss. In a urea hydrolysis study, urea granules were applied to three soils, and hydrolysis measured for 10 d. The urea granules were untreated, or treated with Nutrisphere‐N (Verdesian Life Sciences, Cary, NC), NZone (AgXplore, Parma, MO), or Agrotain Ultra (Koch Agronomic Services, Wichita, KS). Agrotain Ultra was effective in slowing urea hydrolysis, but amending the granules with Nutrisphere‐N and NZone did not slow urea hydrolysis. In a ammonia volatilization study, the treatments were the same, two soils were used, and volatilization was measured over 14 d. Agrotain Ultra was effective in reducing ammonia loss compared to untreated urea granules, but amending the granules with Nutrisphere‐N and NZone had little effect. In a nitrification study, three soils were treated with urea granules, SuperU granules (Koch Agronomic Services, Wichita, KS), or urea granules treated with Nutrisphere‐N, NZone, or Instinct (Dow Agrosciences, Indianapolis, IN). The progress of nitrification was measured after 2 and 4 wk of incubation. SuperU granules, or granules treated with Instinct nitrified more slowly than untreated urea granules, amending urea granules with Nutrisphere‐N and NZone did not slow nitrification. The three experiments do not support the use of Nutrisphere‐N or NZone as fertilizer additives for granular urea, for the purpose of reducing N loss.