Effects of form of nitrogen, season, and urea application rate on ammonia volatilisation from pastures

Abstract

Ammonia (NH,) volatilisation from various nitrogenous (N) fertilisers broadcast at different times of year on to pasture at a rate of 3 g/m? N (30 kg/ha N) was measured by an enclosure method. The average percent losses ofNH,-N were: urea, 11.9; diammonium phosphate, 5.3; ammonium sulphate, 1.0; and calcium ammonium nitrate, 0.8. Loss from sulphur-impregnated urea was equal to, or slightly less than that from urea. The loss was positively related to the maximum soil surface pH produced by each of the fertilisers. No seasonal pattern was observed, except that NH, loss tended to be lower in August-September. The loss from urea increased from 13 to 33% of N applied as the application rate increased from 3 to 20 g/rn? N (30-200 kg/ha N).

Treating grazed pasture soil with a nitrification inhibitor, eco‐n™, to decrease nitrate leaching in a deep sandy soil under spray irrigation—a lysimeter study

“…Urea was applied in solid form and was broadcast over the surface of the lysimeters followed by 10 mm of irrigation to reduce ammonia volatilisation loss (Black et al 1985). Fresh urine was collected from Friesian cows, analysed, and applied to the lysimeters on the same day.…”

“…The amount of N lost by NH 3 volatilisation from the cow urine or urea (±eco-n) and a Control soil (no N applied) was measured using a chamber method as described by Black et al (1985). Urine was applied at 1000 kg N ha-1 and urea at 25 kg N ha-1 (equivalent to an annual rate of 200 kg N ha-1 in eight applications).…”

A lysimeter study of the fate of15N‐labelled nitrogen in cow urine with or without farm dairy effluent in a grazed dairy pasture soil under flood irrigation

“…The amount of N lost by volatilisation from the Urine only, DE, and Control was measured using a chamber method as described by Black et al (1985) immediately after the application of the N sources. Measurements were made from four replicates of each treatment and were continued for a 3-week period.…”

Nitrogen Related Diffuse Pollution from Horticulture Production—Mitigation Practices and Assessment Strategies

“…Application of urea before the onset of rain can significantly reduce the amount of ammonia volatilization because it washes the urea and ammonium below the soil surface. A study reports that 10-16 mm of rainfall soon after application of urea reduced the loss by over 80% [106]. Applying irrigation water after the application of urea fertilizer can also reduce the risk of ammonia volatilization [107].…”

“…Splitting fertilizer applications to match plant demand will also reduce volatilization and leaching losses [106].…”