Effects of Traditional Grazing and Deferred Grazing on Nutrient Cycling.

Management intensive grazing (MIG) has been implemented as a low input alternative to traditional grazing or haying practices. MIG involves high stocking rates of livestock rotated through several small pastures, or paddocks, typically grazing the area for a short period of time. Deferred, or stockpiled grazing, is used to extend the grazing season. Deferred pastures accumulate forage during the late summer and early fall and are grazed in the late fall and early winter. This practice reduces the amount of baled hay needed for winter feeding; thereby reducing winter feed costs. This study investigated the potential for nitrogen and phosphorus leaching in tall fescue (Festuca arundinacea) plots under three different grazing techniques: no grazing (NG); deferred grazing (DG); and standard management intensive grazing (MIG). The NG plots were mechanically harvested. The DG plots utilized standard MIG until the last grazing event when it was allowed to stockpile until late November, when it was the only treatment grazed. Plots were grazed for 24 hours, approximately every 6 weeks. Leachate was collected bi-weekly from zero-tension lysimeters at a depth of 1 meter. Leachate samples were analyzed for nitrate-nitrite and inorganic dissolved phosphorus. Bulk density samples and soil samples were collected prior to grazing, and after the normal grazing season ended. Soil samples were analyzed for available nitrogen (N) and phosphorus (P). Data was analyzed using PROC Mixed with Repeated Measures. Although few significant differences were found after one year of grazing, some trends were observed. DG tended to lose more N in the leachate, and have more soil N removed (either through leaching, plant utilization, or volatilization) throughout the season. DG also lost or utilized more P in the top soil than the other treatments. This is most likely due to the continued growth of the tall fescue in the fall.