The influence of sward mass, defoliation and watering on ammonia volatilization losses from an Italian ryegrass sward topdressed with urea
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Using intact pasture sods with 0.15m2 surface area and sealed in volatilization chambers, the influence of the mass of herbage on the ammonia volatilization losses following a surface application of urea was determined. Ammonia volatilization loss increased as sward mass decreased. This effect was still evident in poorly established pastures.
Under drying conditions the timing of defoliation and water applications relative to the application of urea was also shown to influence ammonia volatilization patterns and magnitude of loss. Delaying defoliation promotes a reduction in ammonia volatilization losses while delayed watering resulted in increased losses.
Key wordsammonia volatilization urea pasture defoliation water application
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- 1.Denmead OT, Freney JR and Simpson JR (1976) A closed ammonia cycle within a plant canopy. Soil Biol Biochem 8: 161–164Google Scholar
- 2.Harper LA, Catchpoole VR, Davis R and Weir KL (1983) Ammonia volatilization: Soil, plant, and microclimate effects on diurnal and seasonal fluctuations. Soil Sci Soc Am J 75: 212–218Google Scholar
- 3.Hoult EH, Barlow EWR and McGarity JW (1974) Air temperature control in nitrogen volatilization chambers. Pl Soil 40: 413–416Google Scholar
- 4.Hoult EH and McGarity JW (1978) Predicting fertilizer interception by swards. J Br Grassld Soc 33: 57–60Google Scholar
- 5.Hoult EH and McGarity JW (1986) Distribution of urease in a pasture sward. Pl Soil 93: 359–366.Google Scholar
- 6.Hutchinson GL, Millington RJ and Peters, DB (1972) Atmospheric ammonia: Absorption by plant leaves. Science 175: 771–772Google Scholar
- 7.Martin JP and Chapman HD (1951) Volatilization of ammonia from surface-fertilized soils. Soil Sci 71: 25–34Google Scholar
- 8.McGarity JW and Hoult EH (1971) The plant component as a factor in ammonium volatilization from pasture swards. J Br Grassld Soc 26: 31–34Google Scholar
- 9.Sherlock RR and Goh KM (1985) Dydnamics of ammonia volatilization from simulated urine patches and aqueous urea applied to pasture. III. Field verification of a simplified model. Fert Res 6: 23–36Google Scholar
- 10.Yamada Y, Wittwer sHG and Bukovac MJ (1965) Penetration of organic compounds through isolated cuticular membranes with special reference to14C urea. Plant Physiol 40: 170–175Google Scholar