Soil management impacts on soil carbon sequestration by switchgrass

Increased atmospheric carbon dioxide (CO2) could have negative impacts on t he environment. Producing and creating bioenergy in the form of biofuels an d electricity from crops is a practical approach to reducing CO2 buildup by displacing fossil fuels and sequestering carbon (C). The use of switchgras s (Panicum virgatum L.) as an energy crop can contribute to clean burning f uels, but no studies addressing soil C sequestration as influenced by use o f switchgrass as an energy crop have been conducted. Our objective was to d etermine the effect of different cultural practices on soil C sequestration under switchgrass. Field experiments were designed to provide differences in row spacing, nitrogen (N) rate, switchgrass cultivar, and harvest freque ncy on a variety of soils. Our results showed that N application, row spaci ng, harvest frequency, and switchgrass cultivar did not change soil organic C in the short-term (2-3 yr) after switchgrass establishment. However, aft er 10 yr under switchgrass soil organic C was 45 and 28% higher at depths o f 0-15 and 15-30 cm, respectively, compared with fallowed soil in an adjace nt area. It appears that several years of switchgrass culture will be requi red to realize a soil C sequestration benefit. (C) 2000 Elsevier Science Lt d. All rights reserved.