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Urea powder and granules of varying size (1 to 8 mm diameter) were surface applied to a ryegrass/white clover pasture. Evolution of NH3 was measured using a continuous air flow enclosure method. At 30 kg N ha−1, the percentage of urea-N lost as NH3 from powder or granules of 1–2, 3–4, 5.6 and 8 mm diameter was 18, 17, 20, 22 and 32 respectively. As the(More)
Ammonia (NH3) volatilization losses from simulated sheep urine patches in a perennial ryegrass (Lolium perenne L.)/white clover (Trifolium repens L.) pasture in New Zealand were measured in the field during the summer, autumn and winter periods. An enclosure technique was used with microplots (23 cm diameter) receiving either sheep urine or aqueous urea at(More)
Theoretical considerations for the development of a simplified model for predicting volatilization losses of ammonia gas (NH3(g)) from the urine patches of grazing herbivores in a pasture ecosystem are presented. The volatilization of NH3(g) is treated as a physico-chemical phenomenon based on the soil solution chemistry of urine patches to develop a(More)
Published field experimental data [11, 15, 19] were used to compare measured NH3(g) losses following applications of urine or aqueous urea to pasture soils with values predicted by a simplified ammonia volatilization model [16]. Total measured losses were generally in close agreement with predictions. For example, predicted losses following applications of(More)
Fused biconic taper (FBT) couplers are essential elements in any fibre-optic communications network. We describe two prototype manufacturing process that produces low-loss fibre tapers and fused FBT coupler devices using CO2 lasers as the heat source instead of a flame, as is the norm in modern manufacturing methods. The methods could potentially be(More)
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