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The Center for Native Grasslands Management

Title: Timing one-cut harvest of switchgrass with optimum decline in phosphorus and potassium levels in aboveground biomass
Year: 2010
Author(s): Lane, J., Allen, F., Sams, C., Barickman, C.
Source Title:
Source Type: Proceedings
pages: 39
Original Publication:  
Abstract: Switchgrass remobilizes nutrients, especially phosphorus and potassium, during senescence. Identifying the appropriate harvest window in a one-cut biomass system based on the remobilization of these nutrients can be economically beneficial for producers. The objective of this research was to determine if a one-cut harvest can be executed earlier in the fall based on the optimum timeframe of translocation of phosphorus and potassium from stems and leaves to the crown and roots. The current recommendation is to harvest after the first killing frost or early November, whichever comes first. In 2007, ‘Alamo’ and ‘Kanlow’ cultivars were planted at the East Tennessee Research and Education Center in Knoxville. Ten plant tillers, clipped at 3-5 cm above ground level, were collected from each plot throughout the fall (July through November, 2008). Each 10 tiller sample was separated into panicles, leaves, and stems then ground and analyzed for P and K. Although P and K levels declined numerically throughout the fall, there were not significant changes in stems or leaves from July to late October for both varieties. Conversely, both P and K substantially increased in the stems and leaves collected in November. The P and K levels were: panicle > leaves > stems. Potassium ranged from 3X-9X higher than P in different tissues. Data from crowns, roots and above ground biomass (2009) followed the same trends observed in the tillers (2008). Based on these results, harvest can be executed earlier in the fall (e.g., late September) without removing significantly more P and K.
Publisher: Proceedings of the Seventh Eastern Native Grass Symposium. Knoxville, TN, October 5-8, 2010
Editor(s): C. Harper