Approaches to assess the environmental impact of organic farming with particular regard to Denmark

Ever increasing attention is being paid to the environmental impact of inte nsive agricultural practices, and in this context organic farming is gainin g recognition as a relatively friendly production system. In general, the r isk of harmful environmental effects is lower with organic than with conven tional farming methods, though not necessarily so. This review examines org anic fanning in the light of European conditions with special regard to rec ent research findings from Denmark. It specifies the environmental problems caused by modern farming practices and discusses appropriate indicators fo r assessing their impact. A driving force-state-response (DSR) framework is employed to organise and understand the processes and mechanisms that lie behind the impact of agriculture on nature and the environment. Important g roups of environmental indicators are selected that characterise (a) the aq uatic environment (nitrate and phosphorus leaching), (b) the soil (organic matter, biology and structure), (c) the ecosystem (arable land, semi-cultiv ated areas, small biotopes and landscape), and (d) resource usage and balan ces (nitrogen, phosphorus, potassium and energy use). The paper also reviews several empirical studies. With regard to soil biolo gy, organic farming is usually associated with a significantly higher level of biological activity (bacteria (Monera), fungi (Mycota), springtails (Co llembola), mites (Arachnida), earthworms (Lumbricus terrestris)), due to it s versatile crop rotations, reduced applications of nutrients, and the ban on pesticides. In most cases there is also a lower surplus of nutrients and less leaching with organic than with conventional farming. However, poor m anagement (e.g., the ploughing of grass and legumes (Fabates) at the wrong time of year with no subsequent crops to capture the mineralised nitrogen), low self-sufficiency in feed, and problems with certain production systems (such as those involved in organic pig farming, i.e., grazing sows, low cr op yields), can lead to a high level of leaching in some organic systems. O rganic farming is faced with a need to expand and develop in line with incr easing demands for organic food and growing environmental concerns. This re quires closer attention to the goals, values and principles on which organi c practices are based, and more research into the influence of organic farm ing on different aspects of the environment. (C) 2001 Elsevier Science B.V. All rights reserved.