Ammonia volatilization from urea, ammonium sulfate and NutraSweet sludge in bare and straw‐covered soils

NutraSweet sludge, a by‐product from the manufacture of the artificial sweetner aspartame, is often applied to land as fertilizer. In many cases, the sludge is surface‐applied, which could result in gaseous losses of nitrogen. In order to determine the relative importance of nitrogen losses through ammonia volatilization, a laboratory study was conducted to compare NutraSweet sludge with ammonium sulfate and urea at equivalent rates of nitrogen. The materials were surface‐applied to two soils in the presence or absence of a surface mulch of straw, and ammonia volatilization was measured over a 16‐day period at 25°C. The soils were collected from areas mapped as Tifton (Fine loamy, siliceous, thermic Plinthic Paleudults) and Dothan (Fine loamy, siliceious, thermic Typic Hapludults) series, respectively. The results show that relative to urea, the NutraSweet sludge loses ammonia more slowly throughout the incubation period but particularly in the initial stages. The straw did not affect ammonia volatilization in Tifton soil, but significanly reduced the loss of ammonia from NutraSweet sludge and urea in Dothan soil. To ensure maximum utilization of the nitrogen applied, the sludge should be incorporated into the soil whenever possible.