NITROGEN RECOVERY BY TIMOTHY FROM SURFACE APPLICATION OF DAIRY-CATTLE SLURRY

Field experiments were conducted on a Buxton silt loam (fine, illitic, frigid Aquic Dystric Eutrochrepts) to determine the effect of surface application of dairy cattle slurry on nitrogen (N) recovery by timothy (Phleum pratense L.). Two experiments were conducted over two years. The experiments differed in the timing of both treatment application and forage harvest. This research indicated that the higher rates (supplying 186 and 267 kg N/ha) of slurry did not consistently increase total yearly yield or percent N recovery by timothy in Maine. The lighter rates (supplying 132 and 134 kg N/ha) had the advantage of less physical suppression of growth during the first cut following application and is, therefore, recommended. Spring application of slurry provided the greatest N recovery due to greater uptake by the cool-season grass than later in the growing season in the spring and is, therefore, recommended over summer application. If spring application is not feasible, summer application of a moderate rate of slurry would allow more slurry disposal without a reduction of yield. Although N recovery from the slurry was relatively low, the potassium (K) concentrations in the forage indicate that the slurry supplied K to the crop at a relatively high level. The ability of the slurry to recycle K may be the major benefit to surface-applied slurry in crop production.