Mitigating diffuse water pollution from agriculture: riparian buffer strip performance with width.

Abstract

Abstract There is currently a dearth of empirical evidence on the performance of most options for mitigating diffuse pollution from agriculture across a representative range of environmental and agricultural conditions. Riparian buffers have, however, received more attention than most mitigation options over the past 20 years. Ranges for positive buffer efficacy were found to be 30-100% for sediment, 30-95% for total phosphorus, 10-100% for total nitrogen, 30-100% for pesticides and 53-100% for faecal indicator organisms. Since many of the experiments underpinning this evidence base were conducted under 'ideal' operating conditions, it is likely that buffer performance in reality will be further hampered by a number of factors such as compaction or the occurrence of concentrated flows. Overall, the evidence base suggests that buffers provide useful short-term benefits, but the longer-term impacts remain questionable owing to risks of pollution swapping. Optimal buffer performance will be site-specific and typically limited in duration, thereby requiring a targeted approach for deployment. Assessing the implications of the reported ranges in buffer performance for implementing a targeted approach remains a key challenge.