| Summary: | Abstract Best management practices for switchgrass (Panicum virgatum L.) fertilization in the production of biofuel feedstock and forage hay are variable depending on climate, harvest timing, and variety. A study of N fertilization was conducted to evaluate the yield response, nutrient removal, and nitrogen use efficiency (NUE) in 12 yr old switchgrass stands in Stillwater, OK. Seven rates of N fertilizer were applied ranging from 0 to 235.2 kg N ha−1 for 3 consecutive years (2008, 2009, and 2010). Positive linear trends in yield with increasing rates of N fertilizer (P < .05) were observed in two out of three years. Differences in N removal due to N fertilization were found in all studied years although responses were inconsistent. Nitrogen concentration in harvested biomass increased as N rates and biomass yield increased. Nitrogen use efficiency increased with N rate (P < .05) although many NUE values were negative up to application rate of 100.8 kg N ha−1. Better understanding of nutrient uptake and use efficiency, removal with harvests, and cycling within the plant could provide more refined fertilization practices in switchgrass production.
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