Nitrogen affecting switchgrass yield, nitrogen removal, and use efficiency

Abstract

AbstractBest 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.