Effects of irrigating dairy-grazed grassland with farm dairy effluent on nitrous oxide emissions

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• 作者：Jiafa Luo ; Surinder Saggar ; Rita Bhandral ; Nanthi Bolan ; Stewart Ledgard ; Stuart Lindsey and Wentao Sun
• 关键词：Farm dairy effluent ; Dairy ; grazed pasture ; Irrigation ; Mitigation strategies ; Nitrous oxide emission ; Poorly drained soil ; New Zealand
• 刊名：Plant and Soil
• 出版年：2008
• 出版时间：August, 2008
• 年：2008
• 卷：309
• 期：1-2
• 页码：119-130
• 全文大小：223.9 KB

文摘

While irrigation of farm dairy effluent (FDE) to land is becoming popular in New Zealand, it can lead to increased emissions of the greenhouse gas nitrous oxide (N₂O). This paper reports the results from trials on N₂O emissions from irrigation of FDE to two dairy-grazed pastures on two poorly drained silt-loam soils located at Waikato and Manawatu, New Zealand. These pasture soils were periodically irrigated with FDE under contrasting soil moisture conditions with water-filled pore-space (WFPS) ranging between 26 % and 94 % . Nitrous oxide emissions were measured from the FDE irrigated and unirrigated sites using large numbers of static chambers (12–20). Irrigation of FDE generally increased N₂O emissions compared to the control. N₂O emissions varied with changes in climatic conditions and soil WFPS. Overall N₂O emissions from effluent-derived N ranged between 0.01 % and 4.93 % depending on irrigation time and soil WFPS. Lower N₂O emissions from FDE were attributable to very low soil WFPS conditions during the dry seasons. Higher N₂O emissions were measured from application of FDE to a recently grazed pasture on wet soil. Our results suggest strategic application of FDE during dry summer and autumn seasons can reduce N₂O emissions from application of FDE. Delaying effluent-irrigation after grazing events could further reduce N₂O emissions by reducing the levels of surplus mineral-N.