Effect of switchgrass plantations on soil acidity, organic carbon, and total nitrogen in a semiarid region

Abstract

Switchgrass (Panicum virgatum L.) has been recognized as a potential energy crop. The effect of its plantation on marginal land was investigated in Inner Mongolia. This study determined the dynamics of pH, electrical conductivity (EC), organic carbon (SOC), and total nitrogen (TN) for six soil layers to 90 cm (35.4 in) depth and bulk density of 0 to 20 cm (0 to 7.9 in) soil layer under switchgrass compared to native grasses in a semiarid region of Inner Mongolia. Soil samples were collected under switchgrass stands established in 2006 (SG2006), 2008 (SG2008), and 2009 (SG2009), and native grasses as a control, during 2012 and 2013. At 0 to 15 cm (0 to 5.9 in) soil layer, soil pH decreased significantly from 8.9 for the control to 8.4, 8.5, and 8.6 for the SG2006, SG2008, and SG2009 stands, respectively. The average EC of the six soil layers declined from 141.6 μS cm⁻¹ for SG2006 to 125.4 μS cm⁻¹ for SG2009. The average SOC increased from 6.59 g kg⁻¹ for SG2009 to 7.73 g kg⁻¹ for SG2006, compared with 8.79 g kg⁻¹ for the native grasses. The average TN decreased from 0.34 g kg⁻¹ for the control to 0.27 g kg⁻¹, 0.28 g kg⁻¹, and 0.30 g kg⁻¹ for SG2009, SG2008, and SG2006, respectively. Although switchgrass planting resulted in a decline of SOC and TN three to four years after being established, there was an obvious increasing SOC and TN trend with plantation period. This study elucidated the importance of switchgrass planting on marginal lands in order to improve soil chemical components that will be related to soil stability and improvement of primary production for energy usage in the future.