|BERTRAM, MICHAEL - University Of Wisconsin
|COFFEY, KENNETH - University Of Arkansas
Submitted to: Popular Publication
Publication Type: Popular Publication
Publication Acceptance Date: 10/17/2014
Publication Date: 10/20/2014
Citation: Coblentz, W.K., Muck, R.E., Borchardt, M.A., Spencer, S.K., Jokela, W.E., Bertram, M.G., Coffey, K.P. 2014. Application of dairy slurry on alfalfa fields, and subsequent effects on nutritive value and silage fermentation characteristics of the harvested forage. Popular Publication. Midwest Forage Assn. Project Reports 2013.
Technical Abstract: Frequently, dairy producers ask questions about the potential risks of applying dairy manure, usually in liquid or slurry form, to growing alfalfa. In many cases, this management option is considered when storage reservoirs are approaching capacity during summer months. One caution associated with this management practice is the potential to inoculate alfalfa with sources of clostridia from the dairy slurry, thereby risking subsequent undesirable clostridial silage fermentations. The objectives of this project were to assess the effects of dairy-slurry application on the subsequent nutritive value and fermentation characteristics of alfalfa balage. During 2012, dairy slurry was applied to the second (HARV1) and third cutting (HARV2) of alfalfa at an overall mean rate of 42,100 L/ha. Twelve 0.17-ha plots received dairy slurry i) immediately after the previous harvest (stubble), ii) after one week of regrowth, or iii) after two weeks of regrowth. Four 0.17-ha control plots receiving no dairy slurry also were evaluated as controls. Applications of dairy slurry had no effect on dry matter (DM) yield; mean yields for HARV1 and HARV2 were 2,477 and 781 kg DM/ha, respectively. Generally, applications of dairy slurry did not exhibit any meaningful effect on the nutritive value of pre- or post-ensiled alfalfa, nor were fermentation characteristics of the silages affected. Clostridium tyrobutyricum, which is known to negatively affect cheese production, was not detected in the dairy slurry, nor was it found in pre-ensiled forage or fermented silages. Counts for Clostridium cluster 1 were greater for slurry-applied plots compared to controls; there also was evidence across these studies that delaying slurry application for one or two weeks following the previous harvest resulted in further increases in counts of Clostridium cluster 1. Based on these results, applications of dairy slurry are less risky when applied directly to stubble, but risks increase when applications are delayed until after alfalfa has initiated regrowth.