Low soil-water level boosts ammonia volatilization from fertilizers

摘要

Ammonia volatilization is an important mechanism of nitrogen (N) loss from soils applied with ammonium or urea forms of N. This research was conducted with Biscayne Marl Soil and Krome Gravelly Loam from Florida, and Quincy Fine Sand and Warden Silt Loam from Washington. KNO_3, NH_4NO_3, (NH_4)_2SO_4 and urea were applied to the soils, at 45 mg per bottle (75 kg per hectare), with 20% and 80% field capacity (FC). A treatment with no N (control) was also included. The soils were incubated at 11, 20 and 29°C which represents the minimum, average and maximum temperatures, respectively, during potato growing in Washington State. The volatilization was measured in on day 1, 3, 7, 14 and 28. NH_3 emission loss was 2 to 3 fold greater at 20%FC water content than that at 80%. The proportion of N-loss from different N sources varied from 0.21% (for NH_4NO_3) to 25.7% (for (NH_4)_2SO_4). The differences in N loss via emission between the two soil water regimes were 10.7, 18.4, and 25.9 percent, respectively at 29°C, 20°C and 11°C. The result of this research showed that low soil water regime accelerated NH_3 emission. Therefore, soil water management close to field capacity is important not only for optimal crop growth and production, but also for minimizing the N-loss.