ABSTRACT

Agricultural landscapes exhibit a high degree of spatial variability, including variation in soil physicochemical characteristics and agroecosystem management (Drinkwater et al., 1995 and Vasseur et al., 2013), which can affect the activity and composition of the soil biota (Acosta-Martínez et al., 2008 and Schipanski and Drinkwater, 2012). Soil microbes mediate the biochemical transformations of organic matter that underpin essential ecosystem functions, including decomposition, mineralization of plant available nutrients, and nutrient retention. Organic production relies on these

microbially-derived ecosystem functions and thus may be a model system for ecological intensification of agriculture (Jackson et al., 2012). By focusing on building and utilizing soil organic matter (SOM) as opposed to using synthetic fertilizers, organic production systems differ greatly from conventional systems; organic management in many research station trials has been shown to improve soil fertility (Burger and Jackson, 2003 and Gattinger et al., 2012), reduce nutrient losses (Drinkwater and Wagoner, 1998, Kramer et al., 2006 and Syswerda et al., 2012), and reduce global warming potential (Burger et al., 2005 and Cavigelli et al., 2013) while supporting similar crop yields in certain contexts (Seufert et al., 2012).