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Grazing ruminants urinate and deposit N onto pastoral soils at rates up to 1,000 kg ha, with most of this deposited N present as urea. In urine patches, nitrous oxide (NO) emissions can increase markedly. Soil derived CO fluxes can also increase due to priming effects.While NO fluxes are affected by temperature, no studies have examined the interaction of pasture plants, urine and temperature on NO fluxes and the associated CO fluxes. We postulated the response of NO emissions to bovine urine application would be affected by plants and temperature. Dairy cattle urine was collected, labelled with N, and applied at 590 kg N ha to a sub-tropical soil,with and without pasture plants at 11°, 19°, and 23°C. Over the experimental period (28 days), 0.2% (11°C with plants) to 2.2% (23°C with plants) of the applied N was emitted as NO. At 11°C, plants had no effect on cumulative NO-N fluxes, whereas at 23°C, the presence of plants significantly increased the flux, suggesting plant-derived C supply affected the NO producing microbes. In contrast, a significant urine application effect on the cumulative CO flux was not affected by varying temperature from 11-23°C or by growing plants in the soil. This study has shown that plants and their responses to temperature affect NO emissions from ruminant urine deposition. The results have significant implications for forecasting and understanding the effect of elevated soil temperatures on NO emissions and CO fluxes from grazed pasture systems. [ABSTRACT FROM AUTHOR]

Soil moisture content (SMC) and throughfall were monitored along transects between rows of radiata pine ( Pinus radiata D. Don) planted at 7 m row spacing and grown with ryegrass/clover or lucerne pastures or with no understorey. SMC was recorded to 1 or 2 m depths for years 2–6 or 4–6, respectively. The predominant rainfall from the south–south–west (SSW) direction created rain shadows (60% of open pasture) on the northern sunny side of the trees. The rain shadows increased as the trees grew but their position were modified by stand pruning and thinning in years 4 and 5. SMC in the top meter showed strong positional effects with the lowest SMC under the tree crowns and on the northern side. There were strong seasonal patterns driven by high spring and summer evapotranspiration, modified by rain shadows and stand age. For the no-understorey treatment, SMC remained high midway between tree rows until the trees were 4 years old and started utilizing this moisture. For the two pasture understoreys, the difference in SMC between the north and south sides decreased with time after trees were thinned and pruned. In the no-understorey there was little difference between the two aspects. Understorey evapotranspiration and fine rooting patterns also helped explain soil moisture use patterns. No difference was detected between two contrasting radiata pine tree types. The effective rooting depth of the ryegrass/clover understorey was <0.7 m while that of lucerne and trees were deeper. Alternative tree planting practices may reduce some of the negative effects of tree-understory moisture competition. [ABSTRACT FROM AUTHOR]