Pesticide pollution of surface water from agricultural sources is caused by surface run-off or field drainage or by point-source pollution from sprayer filling areas and farmyards. Surface run-off can be reduced by reducing soil erosion through permanent vegetated buffer zones along field edges and/or across large fields, reducing soil compaction, and by careful attention to the timing of pesticide applications in relation to rainfall and soil moisture status. However, many UK fields are under-drained and reducing losses via field drainage is difficult, as herbicides are predominantly applied in late summer when soils may be cracked and entry into the soil water occurs very quickly. Pollution from sprayer filling areas and farmyards is more easy to address through the installation of covered pesticide handling areas with separate water drainage systems. Permanent vegetated buffer strips can be effective in preventing pesticide pollution to surface water through surface run-off, though they will not prevent pollution through field drainage flow196. In fields with pipe or tile drainage, soil runoff can be stored or blocked, thereby reducing pesticide pollution, through the incorporation of a small trench and/or elevated ridge just before the watercourse, and/or a strip of vegetation that is semipermanently or permanently wet (Dworak et al 2009197). A large survey in Germany indicated that riparian buffer strips must be at least 5m in width to effectively mitigate the effects and exposure of pesticides (Bunzel et al 2014198). A three zone design has been proposed for its multiple benefits, comprising a permanent grassy crop margin, a strip with shrubs or short rotation trees, and an undisturbed zone with tall vegetation on the bank (Christen and Dalgaard 2013199). Ideally, the design of buffer zones in any given area would be based on a sound diagnosis at the catchment or the hill slope scale (Carluer et al 2014200). Examples from case studies In Denmark, the Buffer Zone Law (also called Border Zone Act) came into force in September 2012 and requires 10m buffer zones along all watercourses (but not ditches with standing water) and around lakes larger than 100m2 (with minor exceptions). The buffer zones cannot be fertilized, sprayed with pesticides or cultivated (Elbersen et al 2014201). The farmer cannot be compensated for the allocation of the land, but is entitled to an annual grant for establishment.
196
http://www.getpelletwise.co.uk/news/buffer_zones_are_not_the_whole_solution/ Dworak, T, Berglund, M, Grandmougin, B, Mattheiss, V and Nygaard Holen, S (2009) International review on payment schemes for wet buffer strips and other types of wet zones along privately owned land. Study for RWS-Waterdienst, Ecologic, Berlin. 198 Bunzel, K, Liess, M and Kattwinkel, M (2014) Landscape parameters driving aquatic pesticide exposure and effects. Environmental Pollution No 186, pp90-97. 199 Christen, B and Dalgaard, T (2013) Buffers for biomass production in temperate European agriculture: A review and synthesis on function, ecosystem services and implementation. Biomass and Bionenergy No 22, pp53-67. 200 Carluer, N, Tournebize, J, Gouy, V, Margoum, C, Vincent, B and Gril, J J (2011) Role of buffer zones in controlling pesticides fluxes to surface waters. Procedia Environmental Sciences No 9, pp21-26. 201 Elbersen, B, Beaufoy, G, Jones, G, Noij, G J, Doorn, A v, Breman, B and Hazeu, G (2014) Aspects of data on diverse relationships between agriculture and the environment. Final report for DG-ENV contract no: 070307/2012/633993/ETU/B1. Alterra in cooperation with EFNCP, Wageningen, The Netherlands. http://ec.europa.eu/environment/agriculture/pdf/report_data_aspectsAgriEnv.pdf 197
44