Organic Agriculture

Organic agriculture and its produce is becoming increasingly popular amongst the general public. Much of this popularity stems from concerns over the health effects of the pesticides used in conventional agriculture. Growers of conventional crops are permitted to utilise a wide variety of over 450 ‘agrochemicals’ in the production and storage of foodstuffs including organophosphorus, organonitrogen, organochlorine, sulfonylurea, carbamate, benzimidazole and quaternary ammonium compounds. In contrast, for food stuffs to qualify as organic under law, only a handful of pesticides are accepted including copper ammonium carbonate, copper sulphate, copper oxychloride, sulphur, rotenone and soft soap. However, the substitution of ‘organic’ for ‘chemical’ fertilisers during the growth of plants does not automatically assume that toxicity will not occur with organic alternatives. Organic fertilisers are subject to the same toxicological assessment as any other chemical utilised in the production of food.

‘Organic’ then is a term defined by law and all organic food production and processing is governed by a strict set of guidelines. The British governing body is the independent UK Register of Organic Food Standards (UKROFS), which sets the basic standards to which various organic bodies and producers have to adhere. United Kingdom standards in turn conform to the European Community directive on organic production. Broadly, organic farming can be defined as an approach to agriculture where the aim is to create integrated, humane, environmentally and economically sustainable agricultural production systems. This involves protecting the long term fertility of the soil by maintaining organic matter levels; nitrogen self-sufficiency through the use of legumes and biological nitrogen fixation; pest control relying primarily on crop rotation, natural predators, resistant varieties and diversity; extensive management of livestock, paying full regard to their evolutionary adaptations; and careful attention to the impact of farming systems on the wider environment.

Data published in nature in 2001¹ demonstrated that organic apple production systems produce similar yields to conventional systems, but have higher soil quality as measured by comparison of physical, chemical and biological soil properties via a soil quality index. The four soil functions evaluated were accommodating water entry, accommodating water movement, resisting surface structure degradation and supporting fruit quality and productivity. These same authors also demonstrated that the ratios of soluble solid (sugar) contents to acidity (tartness), an indicator of sweetness, were most often highest in organic fruit and that organic fruit was firmer. This higher sweetness and lower acidity may indicate differences in nutritional profiles between conventional and organic apples, derived perhaps, from the differing soil quality. Some studies have shown higher mineral content in organic versus non organic foods² (table 1.).

Table 1. Comparison of organic agriculture versus conventional agriculture. Values are mean values for potatoes, wheat, sweet corn, apples and pears².

A meta-analysis of studies comparing organic foods with conventional foods³ found higher levels of vitamin C (+21 %), iron (+21 %), magnesium (+29 %), phosphorus (+13 %), chromium (+86 %), iodine (+498 %), molybdenum (+152 %) and selenium (+372 %) in organic foods. In addition to this the same author also found lower levels of nitrate (-15 %). However, the benefits of organic versus conventional agricultural produce remain controversial in the mainstream, which is not surprising given the powerful lobbying status of conventional agriculture, particularly in the United States. What is surprising is that little research has been performed to measure the difference in polyphenol levels between conventional and organic crops. In recent years the polyphenol group of chemicals has attracted much interest in scientific research because of their possible benefits to human health. Because the exact role of some polyphenols is not fully understood, comparisons of level contained within conventional and organic produce would seem justified.

RdB

¹Reganold, J. P., Glover, J. D., Andrews, P. K. and Hinman, R. H. 2001. Sustainability of three apple production systems. Nature. 410: 926-929

²Smith, B. L. 1993. Organic foods Vs supermarket foods: element levels. Journal of Applied Nutrition. 45(1): 35-39

³Worthington, V. 2001. Nutritional quality of organic verses conventional fruits, vegetables, and grains. Journal of Alternative and Complementary Medicine. 7(2): 161-173