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Title: LOW FIELD CAPACITY BOOSTS AMMONIA VOLATILIZATIONS FROM FERTILIZERS ON DIFFERENT SOILS IN WASHINGTON AND FLORIDA

Author
item LIU, GUODONG - UNIV FLORIDA, HOMESTEAD
item LI, YUNCONG - UNIV FLORIDA, HOMESTEAD
item Alva, Ashok

Submitted to: Plant Nutrition Colloquium Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 6/1/2005
Publication Date: 9/19/2005
Citation: Liu, G., Li, Y., Alva, A.K. 2005. Low field capacity boosts ammonia volatilizations from fertilizers on different soils in washington and florida. Plant Nutrition Colloquium Proceedings. (On CD)

Interpretive Summary:

Technical Abstract: Ammonia volatilization is an important mechanism in gaseous loss of nitrogen (N) from soils applied with high rates of N fertilizers. In order to better understand the N loss, this research was conducted with Biscayne marl soil and Krome Gravelly Loam, from Florida, and Quincy Fine Sand and Warden Silt Loam, from Washington. Weighed portions (300 g dry weight) of the above soils, in three replications were placed in a 500 ml plastic bottle (60 cm2 surface area). Nitrogen was applied at 45 mg per bottle (equivalent to 75 kg N/ha based on surface area) as either potassium nitrate, ammonium nitrate, ammonium sulfate or urea. The soil moisture was adjusted at either 20% or 80% field capacity (FC). A control without any fertilizers was included. The soils were incubated at either of 11, 20 or 29 oC which represent the minimum, average and maximum temperatures, respectively, during potato growing season in Washington. The volatilized ammonia was trapped in a sponge placed in the bottle mouth. The sponge was spiked with 0.8 ml trapping solution containing phosphoric acid-glycerol mixture. The trapped ammonia per sponge was extracted in 25 ml 1 mol/L KCl on day 1, 3, 7, 14 and 28. The extracts were analyzed for ammonium by using an Autoanalyzer. Ammonia volatilization rate was 2 to 3 fold greater with 20% FC than that with 80% FC, one day after the fertilizer application. However, the differences between 20% FC and 80% FC were even much bigger for day 3, day 7, day 14 and day 28. Temperature quotient (Q9) for the volatilization was over 1.1 for most N rates across all soils, except that for Warden Silt Loam with ammonium sulfate, which had a quotient of >10. Krome Gravelly Loam soil had the highest loss of ammonia, while Biscayne marl soil had the least loss. The volatilization loss rate ranges were between 909.9 (ammonium nitrate) and 3021.7 (urea) g N per day per hectare from day 1 to day 3. Peak rate of ammonia volatilization occurred on day 1 or 3 for most treatments, except in the case of urea applied Krome Gravelly Loam with 20% FC. In the latter, ammonia volatilization increased gradually over the entire duration of the incubation. Ammonia volatilization from potassium nitrate was greater than that for the no N amended treatment. This is indicative of the possibility of some nitrate being reduced into ammonium form, which was then being volatilized. The research results indicated that management practices in crop production greatly influenced the amount of N loss from the soils, as evident from increased ammonia volatilization at low soil moisture conditions as compared to that at the soil moisture content near FC.