Soil fertility in organic farming systems.

Abstract This chapter reviews the components of soil fertility in the context of organic farming systems and how certified organic practices are used to manage soil fertility. Data from long-term field studies evaluating organic farming are discussed in terms of the components of soil fertility. The changes in soil organic matter with implementation of organic matter management treatments in long-term field experiments conducted in South Australia, Switzerland, Norway, California and Washington (USA), are provided. The concept of soil fertility is also viewed in relation to its relevance to the application of organic farming practices across landscapes and soil types in different climatic zones. In addition, the differences in the physical, biological and chemical characteristics of soil fertility in long-term field trials that include organic farming treatment, are also given.