Showing papers by "Keith C. Cameron published in 1985"
TL;DR: Ammonia volatilisation from various nitrogenous (N) fertilisers broadcast at different times of year on to pasture at a rate of 3 g/m2 N (30 kg/ha N) was measured by an enclosure method as discussed by the authors.
Abstract: Ammonia (NH3) volatilisation from various nitrogenous (N) fertilisers broadcast at different times of year on to pasture at a rate of 3 g/m2 N (30 kg/ha N) was measured by an enclosure method. The average percent losses of NH3-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 NH3 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/m2 N (30–200 kg/ha N).
103 citations
TL;DR: In this article, the authors measured the evolution of NH3 from the soil using three methods: an enclosure system with continuous air flow (EM), an unconfined micrometeorological method (integrated horizontal flux method) and by measuring the recovery of N as urea, NH4+ and NO3− (NRM) The cumulative loss after 96 h measured by the three methods was 24, 25% and 30% of the N applied respectively After 144 h the daily rate of loss was small At this time, EM and IHFM estimated the loss at 28
Abstract: SUMMARY
Urea granules were broadcast on to pasture (Lolium perenne/Trifolium repens) at a rate of 100 kg N ha−1 The evolution of NH3 from the soil was measured using three methods: an enclosure system with continuous air flow (EM), an unconfined micrometeorological method (integrated horizontal flux method—IHFM) and by measuring the recovery of N as urea, NH4+ and NO3− (NRM) The cumulative loss after 96 h measured by the three methods was 24%, 25% and 30% of the N applied respectively After 144 h the daily rate of loss was small At this time, EM and IHFM estimated the loss at 28%, while the NRM estimated a 45% loss The higher estimated loss by the NRM was attributed mainly to microbial immobilization of applied N
Hourly fluxes estimated by the EM and the IHFM were very different This was attributed to variations in the rate of urea hydrolysis which appeared to be more rapid in the confined EM system where the rate of soil drying was slower
69 citations