ABSTRACT
Improved soil quality and minimizing soil degradation have long been considered two central elements of a suite of positive broader environmental and ecological attributes from organic farming found within organic standards (CGSB, 2006). Promoting the health and biological characteristics of the soil, which play a key role in the linked processes of decomposition and nutrient cycling, while providing other ecosystem services, is similarly recognized as a key goal of organic cropping systems (Stockdale and Watson, 2009; Lynch et al., 2012a). Surveys of organic farmers (see Chapter 2) also reflect these central interests of organic farm management. Within the topic of soil management, research focused on the optimum use of green manures (GMrs) and management approaches “to improve existing soil life” were the topranked priorities among Canadian organic producers’ research interests (OACC, 2008). Recent reviews such as Gomiero et al. (2011) and Lynch et al. (2012a) have examined soil quality within organic farming in temperate regions as a component
5.1 Introduction .................................................................................................. 107 5.2 Soil Organic Matter ...................................................................................... 108 5.3 Labile Fractions of Soil Organic Matter ....................................................... 114 5.4 Aggregate Dynamics .................................................................................... 116 5.5 Soil Ecology and Soil Health ........................................................................ 117 5.6 Water Infiltration and Water Holding Capacity ............................................ 121 5.7 Reduced Tillage and Zero-Tillage Approaches to Organic Field Crop
Production and Integrating Livestock: Implications for Soil Quality .......... 123 5.8 Future Directions and Research Needs ........................................................124 References .............................................................................................................. 126
of a broader summary of environmental and ecological system impacts including biodiversity, energy use and global warming potential, and nutrient loading. In the following, we focus specifically on the impacts of organic field crop management on soil abiotic and biotic quality, drawing primarily, but not exclusively, on studies conducted in Canada and the United States. Soil fertility and nutrient (nitrogen and phosphorus) dynamics under organic field cropping is covered in Chapter 4. This topic is approached with subsections on (1) soil organic matter, (2) labile fractions of soil organic matter, (3) aggregate dynamics, (4) soil ecology and soil health, (5) water infiltration and water holding capacity, and (6) reduced and zero-tillage approaches and integrating livestock-implications for soil quality-followed by a concluding commentary on (7) future directions and research needs.
