Biochar and Nitrogen Effects on Yield, Plant Nutrients and Soil Health Characteristics in Switchgrass Production.

Switchgrass (Panicum virgatum) is a potential bioenergy crop for the liquid and solid fuels it may produce and the sustainability it provides to the soil. An understanding of methods to reduce input costs of switchgrass while maintaining yields and soil quality is important for its potential role as a bioenergy feedstock. Established switchgrass plots were applied with decreasing levels of nitrogen (N) fertilizer from the recommended levels of 67 kg ha^-1 to 34 and 17 kg/ha^-1 with or without biochar in a randomized complete block design with four replicates in 2014 and 2015. Yield, plant and soil nutrients were monitored on an annual basis in 2014 and 2015 and soil quality analyses (available water capacity, wet aggregate stability, soil respiration, active carbon, ACE protein test) were performed in Spring 2016. An increase in soil carbon was identified in 2015 in plots containing biochar following biochar application. Otherwise, biochar has no significant effects on yield, plant or soil nutrient or quality characteristics. Nitrogen rates of 34 kg/ha^-1 produced yields statistically similar to the recommended application rate of 67 kg/ha^-1, regardless of biochar application, which could indicate a lower requirement under these conditions.