ACE-Protein autoclaved citrate extractable protein PLFA phospholipid fatty acid POX-C permanganate oxidizable carbon USGP US Great Plains 1 INTRODUCTION Integrated cropping systems, where livestock and crops are produced rotationally or concurrently, have been the norm for much of agricultural history. However, the latter half of the 20th century saw a shift toward specialization and a resultant decoupling of livestock from crop production (Hendrickson et al., 2008; Russelle et al., 2007).