Sustainable food system : Targeting production methods, distribution or food basket content?

摘要

Agriculture is the single most important contributor to the eutrophication of the Baltic Sea. Itis responsible for 59% of the anthropogenic nitrogen and 56% of the phosphorous emissions(HELCOM, 2005). A second important source of nutrient emissions is at the other end of thefood system – emissions from municipal waste-water treatment plants and from privatehouseholds. Addressing different aspects of the food system is thus crucial for the Baltic Seaenvironment. To tackle eutrophication both nitrogen and phosphorous loads should bereduced (MVB, 2005). This can be achieved if emissions from the food system are reduced,e.g. by closing the nutrient cycle from soil to crop and back to agricultural soil (Diaz andRosenberg, 2008). Granstedt (2000) finds that the high surplus and emissions of nitrate andphosphorous in Swedish agriculture is a consequence of specialized agriculture with itsseparation of crop and animal production. Similar findings are reported from different partsof Europe (Brower et al., 1995). About 80% of cropland in Sweden is used for fodderproduction but the animal production is concentrated to a limited number of specializedanimal farms. Manure, with its contents of nutrients from the whole agriculture area, istoday concentrated on only 20% of the Swedish arable land (Statistics Sweden, 2011). Thisresults in high nutrient surplus and load of nitrogen and phosphorus from these areas.Granstedt (2000) concludes that the emissions can be limited by combining best availableagricultural technology with increased recycling of nutrients within the agricultural systemtrough integration of crop and animal production - ecological recycling agriculture (ERA).This facilitates an efficient use of the plant nutrients in farm yard manure. Other studies ofnutrient balances comparing farming systems and lifecycle assessment report similarobservations (Halberg, 1999; Myrbeck, 1999; Steinshamn et al., 2004; Uusitalo, 2007). Thepotential of reduced nutrient emissions trough ERA was confirmed in case studies on localorganic farms around the Baltic Sea (Granstedt et al., 2008; Larsson and Granstedt, 2010).Carlsson-Kanyama (1999) found that greenhouse gas emissions could be reduced by localand organic food production due to shorter transportation. Similar results are reported in acompilation of studies (FiBL, 2006) and in studies of local production and processing inJärna, Sweden (Wallgren, 2008). According to Carlsson-Kanyama et al. (2004) the reductionsare not significant unless local distribution becomes more efficient.