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Title: LOW SOIL-WATER LEVEL BOOSTS AMMONIA VOLATILIZATION FROM FERTILIZERS

Author
item LIU, G - UNIV OF FLORIDA
item LI, Y - UNIV OF FLORIDA
item Alva, Ashok

Submitted to: Plant Nutrition Colloquium Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 5/1/2005
Publication Date: 9/1/2005
Citation: Liu, G., Li, Y.C., Alva, A.K. 2005. Low soil-water level boosts ammonia volatilization from fertilizers. Plant Nutrition Colloquium Proceedings. On CD.

Interpretive Summary: A portion of nitrogen fertilizer applied to the soil is lost in the gaseous form, which is termed as 'volatilization loss of N'. This mechanism is, however, dependent on the form of N used, soil conditions, i.e. moisture and pH, and climatic conditions, mainly temperature. In this study, volatilization loss of N was evaluated using either potassium nitrate, ammonium nitrate, ammonium sulfate, or urea from two major potato growing soils each from Florida (FL) and Washington (WA). Soil water regime was maintained at either 20 or 80% of field capacity water content each at three incubation temperatures, i.e. either 11, 20, or 29 degrees C. The results of this study showed that volatilization loss was greater at the lower soil water regime than that at the near field capacity soil water content. This study demonstrated the importance of maintaining soil water content at near field capacity to minimize the N loss and also to avoid any negative effects of soil water stress on plant growth as well as production.

Technical Abstract: 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. Potassium nitrate, ammonium nitrate, ammonium sulfate 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 degrees C which represents the minimum, average and maximum temperatures, respectively, during potato growing in Washington State. The volatilization was measured on day 1, 3, 7, 14 and 28. Ammonia volatilization 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 NH4NO3) to 25.7% (for (NH4)2SO4). The differences in N loss by volatilization between the two soil water regimes were 10.7, 18.4, and 25.9 percent, respectively at 29 degrees C, 20 degrees C, and 11 degrees C. The result of this research proved that low soil water regime accelerated ammonia volatilization. Therefore, soil water management close to field capacity is important not only for optimal crop growth and production, but also for minimizing the volatilization loss of N.