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Providing evidence to improve practice

Individual study: Using nitrogen-15 to quantify vegetative buffer effectiveness for sequestering nitrogen in runoff

Published source details

Bedard-Haughn A., Tate K.W. & van Kessel C. (2004) Using nitrogen-15 to quantify vegetative buffer effectiveness for sequestering nitrogen in runoff. Journal of Environmental Quality, 33, 2252-2262


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Water: Plant buffer strips Mediterranean Farmland

A replicated, randomized, controlled study in summer 2000–2001 in montane pasture in California, USA, found that grass buffer strips reduced the amount of nitrate in runoff from extensively grazed irrigated pasture. Nutrients: Buffer strips reduced the amount of nitrate in runoff (8 m buffers: 28%; 16 m: 42%). Buffers trapped twice the amount of nitrogen, compared to unbuffered plots, in the first four weeks. Implementation options: Buffers trapped higher amounts of runoff in the first four weeks, compared to the next 10 weeks. Methods: Plots (5 x 48 m) were buffered (8 or 16 m) or unbuffered (three replicates each). Fertilizers were applied to plots (170 kg/ha) in May. Five cattle (per 0.2 ha) grazed for two days (faecal matter: 336 kg/ha/plot) every three weeks. Buffer strips had no grazing or fertilizer application. Plots and buffer strips were irrigated in April–October (167 L/s/ha, 3.5 h). Soil berms separated plots. Water samples were collected for 14 weeks following fertilizer (5 kg/ha, traceable potassium nitrate) and water (20 L/m) application. A trough at the bottom of the buffers collected surface runoff and soil solution samplers (45 cm deep) collected subsurface runoff.