Controlling Ammonia Volatilization from Urea Surface Applied to Sugar Beet on a Calcareous Soil

The extent of ammonia (NH3) volatilization from surface-applied urea to sugar beet and effects of NBPT [N-(n-butyl) thiophosphoric triamide] PG (phosphogypsum), PR (by-product-pyrite) and KCl (potassium chloride) on NH3 volatilization, nitrogen (N) content of leaf blades and petioles, sugar, amine N, and refined sugar contents, and root and refined sugar yields were determined in the field. Total NH3 loss varied from 7.0% to 23.6% depending on the compounds incorporated with urea and rate of addition. With respect to unamended urea, 540 kg KCl/ha, 1000 kg phosphogypsum/ha, and 1000 kg pyrite/ha increased NH3 loss by 86.7%, 40.1%, and 36.2%, respectively, but the other treatments decreased the loss. The highest reduction of NH3 loss was found with 0.5% of NBPT by 44.5%. The NBPT, KCI, and PG treatments increased both root and refined sugar yields compared with urea alone. The highest refined sugar yield and lowest NH3 volatilization loss was obtained with 0.5% of NBPT treatment.