, Volume 6, Issue 1, pp 329-335,
Open Access This content is freely available online to anyone, anywhere at any time.

Effect of Potassium and Nitrogen Fertilizer on Switchgrass Productivity and Nutrient Removal Rates under Two Harvest Systems on a Low Potassium Soil


Biomass demand for energy will lead to utilization of marginal, low fertility soil. Application of fertilizer to such soil may increase switchgrass (Panicum virgatum L.) biomass production. In this three-way factorial field experiment, biomass yield response to potassium (K) fertilizer (0 and 68 kg K ha−1) on nitrogen (N)-sufficient and N-deficient switchgrass (0 and 135 kg N ha−1) was evaluated under two harvest systems. Harvest system included harvesting once per year after frost (December) and twice per year in summer (July) at boot stage and subsequent regrowth after frost. Under the one-cut system, there was no response to N or K only (13.4 Mg ha−1) compared to no fertilizer (12.4 Mg ha−1). Switchgrass receiving both N and K (14.6 Mg ha−1) produced 18 % greater dry matter (DM) yield compared to no fertilizer check. Under the two-cut harvest system, N only (16.0 Mg ha−1) or K only (14.1 Mg ha−1) fertilizer produced similar DM to no fertilizer (15.1 Mg ha−1). Switchgrass receiving both N and K in the two-cut system (19.2 Mg ha−1) produced the greatest (P < 0.05) DM yield, which was 32 % greater than switchgrass receiving both N and K in the one-cut system. Nutrient removal (biomass × nutrient concentration) was greatest in plots receiving both N and K, and the two-cut system had greater nutrient removal than the one-cut system. Based on these results, harvesting only once during winter months reduces nutrient removal in harvested biomass and requires less inorganic fertilizer for sustained yields from year to year compared to two-cut system.