Field-Scale Soil Property Changes under Switchgrass Managed for Bioenergy

Authors

Marty R. Schmer, USDA-ARS, University of Nebraska-LincolnFollow
M. A. Liebig, USDA-ARS
K. P. Vogel, University of Nebraska-LincolnFollow
Robert B. Mitchell, University of Nebraska-LincolnFollow

Date of this Version

2011

Comments

Published in GCB Bioenergy (2011), DOI: 10.1111/j.1757-1707.2011.01099.x.

Abstract

The capacity of perennial grasses to affect change in soil properties is well documented but information on switchgrass (Panicum virgatum L.) managed for bioenergy is limited. An on-farm study (10 fields) in North Dakota, South Dakota, and Nebraska was sampled before switchgrass establishment and after 5 years to determine changes in soil bulk density (SBD), pH, soil phosphorus (P), and equivalent mass soil organic carbon (SOC). Changes in SBD were largely constrained to near-surface depths (0–0.05 m). SBD increased (0–0.05 m) at the Nebraska locations (mean=0.16 Mgm^-3), while most South Dakota and North Dakota locations showed declines in SBD (mean=-0.18 Mgm^-3; range=-0.42–0.07 Mgm^-3). Soil pH change was significant at five of the 10 locations at near surface depths (0–0.05 m), but absolute changes were modest (range=-0.67–0.44 pH units). Available P declined at all sites where it was measured (North Dakota and South Dakota locations). When summed across the surface 0.3 m depth, annual decreases in available P averaged 1.5 kg P ha^-1 yr^-1 (range=0.5–2.8 kg P ha^-1 yr^-1). Averaged across locations, equivalent mass SOC increased by 0.5 and 2.4 Mg Cha^-1 yr^-1 for the 2500 and 10 000 Mg ha^-1 soil masses, respectively. Results from this study underscore the contribution of switchgrass to affect soil property changes, though considerable variation in soil properties exists within and across locations.