Set aside is probably the most well known and frequently debated management technique in european agriculture. It was introduced by the European Community as part of the Common Agricultural Policy in 1988 to reduce surpluses and counteract environmental problems as result of intensification of agriculture. In 1995/6, it was estimated that 500 000 ha were designated as set aside, equivalent to 11% arable land although the scheme was suspended in 2008 (Firbank, 1998)(HMRC, 2014).
Modern farming has always been a source if pollutants, particularly nitrates in surface and groundwater and phosphates in surface water from pesticides, sediments and eutrophication. In 2006 a DEFRA funded study analysed the affect of the set aside scheme on levels of certain pollutants. By changing land use, set-aside can reduce the levels of diffuse pollutants entering surface and ground waters as significantly less is sprayed, as demonstrated in the table below.(DEFRA, 2007)
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| Fig. 1- Areas treated with different kinds of pesticides as a percentage of area grown. Treated areas above 100% have been sprayed more than once (DEFRA, 2007). |
The Environment Agency as part of the Water Framework Directive found pollution from nitrate leaching was a major issue in arable areas of the country with East Anglia, Lincolnshire and Humberside worst affected. The study compared nitrate losses for arable systems in clay or sandy soils in dry and wet years with or without the application of organic manure as shown in the table below. The table suggests that the removal of set aside and the reintroduction of arable practice will increase nitrate output by 23-47kg per ha per year for non manure systems (IGER, 2005). When levels are already high, such as the Humberside, additional measures would need to be introduced that may result in increased public expenditure (Hodge et al, 2006).
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| Fig.2- Nitrogen losses from different arable systems with mitigation measures (IGER, 2005). |
A cost benefit analysis was carried out based solely on the area understudy. This suggested that in the cases where additional measures were required, the gain would be the value of net output on 21 000ha plus the value of the output less mitigation costs on 157 000ha. This therefore suggests that in the case of nitrogen leaching, it makes sense to convert set aside. However, the study is simplistic and fails to consider measures to address loss of phosphates and other pollutants along side other risks. Similar results were also found for studies looking at phosphorus levels. Furthermore, evidence also suggests reversion of set aside increased N2O, a greenhouse gas, as a result of an increase in field operations(Hodge et al, 2006)(DEFRA, 2007).
Although set aside does reduce leaching of nitrates and phosphates with slight impact on greenhouse gas emissions, it appears that these impacts do not outweigh the economic impacts of reversion to working land. However, there has been little research on combined pollutants or the impact of set aside as a buffer zone. In addition, the following post will assess the impacts of set aside on plant, vertebrate and invertebrate biodiversity to further assess the schemes significance.
Sources:
DEFRA. 2007. Change in the area and distribution of set-aside in England and its environmental impact. [online]. Available at: http://archive.defra.gov.uk/evidence/statistics/foodfarm/enviro/observatory/research/documents/observatory08.pdf [Accessed 30.12.14]
Firbank, L. 1998. Agronomic and environmental evaluation of set-aside under the EC Arable Area Payments Scheme, vols. 1–4. Institute of Terrestrial Ecology/Ministry of Agriculture, Fisheries and Food, London.
HMRC. 2014. IHTM24064 - Agricultural purposes: Set-aside scheme. [online]. Available at: http://www.hmrc.gov.uk/manuals/ihtmanual/ihtm24064.htm. [Accessed 30.12.14]
Hodge, I. et al. 2006. Project to assess future options for set aside. University of Cambridge. [online]. Available at: http://archive.defra.gov.uk/evidence/economics/foodfarm/evaluation/futuresetaside/Fullreport.pdf [Accessed 30.12.14]
IGER. 2005. Cost Curve of nitrate mitigation options NT2511. Report for Defra. Institute of
Grassland and Environmental Research.
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