Abstract
There are wide variations in fertilizer recommendations for switchgrass (Panicum virgatum L.) as biofuel feedstock or forage. Inconsistent yield responses to fertilization are common. Nutrient translocation, from aboveground leaves and stems to belowground roots, is a contributor to variable, and sometimes the absence of, fertilizer response. A field study evaluated how major nutrients are cycled within switchgrass during the growing season. Aboveground (AG) and belowground (BG) biomasses were harvested and analyzed separately for yield (AG) and nutrient concentrations (AG and BG). Maximum yields were 26.3 (2008), 17.5 (2009) and 29.3 (2010) Mg ha−1 until senescence. In all years, the N concentration of the AG biomass decreased as the season progressed (p < 0.0001). The belowground biomass N concentration increased over time in 2008 and 2010 (p < 0.05). Phosphorus (P) and potassium (K) displayed similar trends to nitrogen concentration. Temporal changes of other nutrients in the AG and BG biomass concentrations were inconsistent and varied compared with N. The dynamics of the macronutrients suggested translocation from AG to BG as the switchgrass matured. Nutrients stored in roots can be beneficial for regrowth in the following growing season, which may reduce response to fertilizers. A greater understanding of nutrient cycling and harvest timing is needed to better manage different switchgrass production systems.
Highlights
Switchgrass (Panicum virgatum L.) has been selected as an ideal biofuel feedstock for the production of biofuels
Nutrients stored in roots can be beneficial for regrowth in the following growing season, which may reduce response to fertilizers
Some works have suggested that nutrient transfer from aboveground portions of the plant (AG) to belowground (BG) is the reason for the poor response to applied nutrients [7]
Summary
Switchgrass (Panicum virgatum L.) has been selected as an ideal biofuel feedstock for the production of biofuels. Have made it useful as a buffer in riparian areas to control erosion [2]. Switchgrass yield response to applied nitrogen (N) has often been inconsistent in fertilization studies [3,4,5,6]. Some works have suggested that nutrient transfer from aboveground portions of the plant (AG) to belowground (BG) is the reason for the poor response to applied nutrients [7]. A transfer such as this would likely be important for regrowth during the following growing season [8,9,10]. Nutrient dynamics within switchgrass plants during the growing season offer insight into the need and use of fertilizer in biomass production
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