Elephant grass has potential as biofuel crop in southern states

By Holly Jessen | October 03, 2012

A drought tolerant grass known as elephant grass or napiergrass that is fed to cattle in the tropics is being studied as a possible cellulosic ethanol feedstock in southern states, with encouraging results.

The research is ongoing as part of a search for alternative biofuel feedstocks under way by two USDA agencies, the Agricultural Research Service and Forest Service Research and Development, the USDA said in a news release. William Anderson, a research geneticist at the ARS Crop Genetics and Breeding Research Unit in Tifton, Ga., believes napiergrass has potential as a biomass crop in areas where the plant survives winters but there is a killing frost, meaning the plant doesn’t flower. “[That] is a positive in that it will not set seed that could cause invasiveness in many areas of the southeast,” Anderson told Ethanol Producer Magazine, adding that the plant isn’t as cold tolerant as switchgrass but has survived as far north as Athens, Ga.

A 2012 publication called BioEnergy Research contains an article based on four years of research on the subtropical grass. It grows well on marginal lands and the areas between land and a river or stream, known as riparian areas, where napiergrass could help improve water quality by filtering out nutrients from row crop field runoff.

The grass is established in the early fall, like sugarcane, is ready for harvest by the next fall and begins growing again in the spring. It is typically harvested once a year but researchers are looking at the possibility of a double harvest, Anderson said. Studies on napiergrass will continue for a number of years. “For sustainability, part of the study will require taking yield for many years to see if yields remain high and what production protocols are needed for the high levels,” he said.

Researchers are testing the crop for capability to improve yield, usable fiber content and disease resistance. Another area of study is whether poultry litter can be used as a soil amendment. In a comparison of synthetic fertilizer versus poultry litter the grass showed little difference in yield. “Using poultry litter provides a good use of waste from poultry houses in the south,” he said. “There are many poultry houses in the south, and though some of it is used for other crops, napiergrass does a good job of taking up the excess phosphorous that poultry litter contains.”

For more information about the study of napiergrass as well as sugarcane and sweet sorghum as potential biomass crops, check out the article published in Agricultural Research, a science publication of the USDA.