Fertilizer and Harvest Management of Switchgrass in Illinois.

The goal of this research will be to develop nitrogen fertilizer management guidelines for switchgrass biomass feedstock production in Illinois.  The specific objectives to achieve the goal will be 1) to determine nitrogen fertilizer application rate and source to maximize biomass production in different regions of Illinois, 2) to determine the effects of N application rates on feedstock quality, and 3) to determine the effects of harvest timing on switchgrass N response and stand longevity. Five fertility treatments, 0, 56, 112, 168, 224 N kg/ha with urea and slow released urea, were applied along with three harvest treatments, summer, fall and the following spring before emergence.  All stands showed a positive response to fertilization rates.  Yields were highest during the summer and decreased with each later harvest.  Even though the summer harvest was the highest, research has shown that nitrogen content is higher in switchgrass biomass harvested at peak standing crop than when the crop is harvested after a killing frost and senescence.  Delaying harvest until the end of the growing season or after a killing frost with single-cut system significantly reduces the nitrogen requirement and maintains the switchgrass stand’s health and longevity.  A healthy stand will help prevent weed competition as well as allow for the yields to remain consistent over time ensuring quality yields from year to year.