Composting for feedlot manure management and soil quality

Contemporary industrialized grain and livestock production is characterized by efficient, large-scale confined animal feedlot operations (CAFOs) and equally efficient and large-scale, but separate, grain operations. Though both are highly productive, feedlot operators have come to view manure as a waste management problem, while grain operations face declining soil quality and a reliance on commercial fertilizers to maximize yields. Neither type of operation can be considered sustainable. Cooperative on-farm composting may provide solutions to some of the problems facing our industrialized agricultural systems and render the systems more sustainable. In this paper we view cooperative on-farm composting as the combination and processing of feedlot manure with crop stover to produce a beneficial natural soil amendment and fertilizer for those fields from which the stover was taken. Cooperative on-farm composting would help protect surface and groundwater from nutrient loading, save resources, and help renew social ties within the agricultural community. Composting stabilizes nutrients, kills pathogens and weed seeds, reduces moisture content, reduces odor, and improves physical properties of manure, thereby improving its value as a soil amendment and fertilizer. Although some N in raw manure is lost during composting, the end product differs from raw manure in that it exhibits minimal N loss in storage or after field application. Composted manure can become the primary fertilizer for grain production once the cumulative N mineralization from previous applications reach steady-state. The use of composted manure improves soil quality and greatly reduces total energy consumption compared with the use of commercial fertilizer. A hypothetical example illustrates how compost applications to irrigated corn (Zea mays L.) could result in a net energy savings of about 3.3 million Btu/acre, which is equivalent to the energy contained in 19.4 gallons of diesel fuel/acre.