ASABE Technical Library - Abstract

Abstract. As animal manure is primarily disposed of on cropland and used as a beneficial soil amendment, the time available for disposal is limited by periods of crop growth as well as climate and soil conditions. Winter has historically been a convenient time for farmers to apply manure as the fields lay fallow and equipment can safely drive on frozen soil without fear of compacting soil or bogging down. However, it is widely recognized that applying manure to hard packed surfaces (such as frozen ground) can increase the risk for bulk runoff of manure as well as the nutrients and pathogens contained within, particularly during periods of high runoff such as spring thaw. At its heart, this is a risk management issue that needs detailed investigation of risk factors in order to assess potential dangers. The urgency for new science concerning winter manure application is increasing because of the potential links to an observed increase of cyanobacteria in the Great Lakes and other vulnerable water bodies. In order to address these issues under controlled conditions, a suite of laboratory studies investigating several parameters key to quantifying the fate associated with winter manure application events are underway, including Runoff relation to snow pack at thaw events for winter/fall manured soils, runoff relation to soil moisture content prior to thaw events for winter/fall manured soils, the effect of macropores, associated with no till management strategies, on nutrient movement during freeze-thaw events for winter/fall manured soils and nutrient movement at the root zone of cover crops under multiple freeze/thaw cycles for fall manured soils.