Agronomic and Environmental Consequences for Switchgrass Grown On Biochar Amended Soils.

Biochar amended soils are thought to positively impact water holding capacity and nutrient retention leading to increased biomass production and reduced loss of reactive N though nitrous oxide emissions. However, the need for surface application and incorporation limits options for biochar application to perennial grasslands such as switchgrass. This study compares pre-plant surface application and incorporation with four years of simulated injections into existing switchgrass stands. The study is being conducted at two excessively wet and two drought prone sites in central Pennsylvania. This report presents preliminary data on location and biochar application method effects on soil water relations, switchgrass growth, and nitrous oxide emissions. Switchgrass biochar was produced by slow pyrolysis then either surface applied at 10 Mg biochar/ha and rototilled into the soil, or applied to chiseled furrows in four yearly applications of 2.5 Mg/ha. The first of the four applications was made in autumn 2011 and the second in 2012. Switchgrass seedlings were transplanted into the field plots in spring 2012. First year switchgrass yield was not significantly affected by the presence of biochar (P = 0.17) or biochar application method (P = 0.13), although a trend existed for plots with biochar to have slightly greater yield than plots without biochar, and rototilled plots to have greater yield than chiseled plots. Yield was significantly affected by location (P < 0.001) with the wettest site having the greatest yield and the driest site the least. Second year yield, soil water and nitrous oxide emission data will be collected during the 2013 growing season. Initial results show no significant advantage or disadvantage of biochar or biochar application method on switchgrass production.