SS AGR 297

Production of Biofuel Crops in Florida: Elephantgrass1

Kenneth R. Woodard and Lynn E. Sollenberger2

1. This document is SS AGR 297, one of a series of the Agronomy Department, Florida Cooperative Extension Service, Institute of Food and Agricultural 

Sciences, University of Florida. Original publication date January 2008. Reviewed March 2011. Visit the EDIS website at http://edis.ifas.ufl.edu.

2. Kenneth R. Woodard, post-doctoral research associate, Agronomy Department; Lynn E. Sollenberger, professor, Agronomy Department; Florida 

Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611.

The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and 

other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, 

sexual orientation, marital status, national origin, political opinions or affiliations. U.S. Department of Agriculture, Cooperative Extension Service, 

University of Florida, IFAS, Florida A. & M. University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Millie 

Ferrer-Chancy, Interim Dean

Introduction 

Elephantgrass (Pennisetum purpureum) was first 

introduced into the United States from Africa in 1913. 

Prior to 1960, research in Florida focused on 

elephantgrass as potential forage for cattle. A new 

research initiative emerged following the oil embargo 

of 1973. In the 1980s, funding for renewable energy 

became available through an agreement between the 

University of Florida's Institute for Food and 

Agricultural Sciences and the Gas Research Institute 

of Chicago, Illinois. A major objective was to identify 

herbaceous plants with the highest biomass yield. 

Early on it became clear that elephantgrass was a 

premier biomass plant. After 15 years of field trials 

conducted in Florida, as well as trials in southern 

Alabama and Georgia, five of the best elephantgrass 

selections for biomass energy were planted in a 

holding nursery in 2000 at the Plant Science Research 

and Education Unit near Citra, FL by Dr. Gordon M. 

Prine. The nursery included Merkeron, N51, N43, 

N13, and PI 300086 elephantgrasses. Merkeron, N51, 

N43, and N13 yielded well throughout Florida and 

have the potential to grow as perennials in the lower 

southeastern USA. Selection PI 300086 is high 

yielding, but stands can be reduced by the more 

severe winters in North Florida. For cold tolerant 

selections, the northern limit for sustained survival 

and adequate yield is the plant hardiness zone where 

temperatures do not drop below 15 to 20°F or -6.7 to 

-9.4°C.

Figure 1. Northern limit of Pennisetum purpureum for 

sustained production in the southeastern USA Credits: 

Woodard, K. Agronomy Department UF/IFAS.

Current Potential for Use as Biofuel 

In the 1980s, energy conversion strategies 

included the use of elephantgrass as a feedstock for 

methane generation or co-firing it with coal to 

produce electricity. Currently, there is widespread 

interest in the production of cellulosic ethanol. The 

feasibility of producing ethanol from cellulosic crops 

such as elephantgrass has greatly improved in recent 

times due to a number of factors: there have been 

improvements in fermentation strains and in methods 

for generating sugars from cellulosic feedstocks; the 

cost of enzymes used to break down cellulose has 
Production of Biofuel Crops in Florida: Elephantgrass 2

been reduced dramatically. In addition, economic 

incentives for cellulosic ethanol production exist due 

to high oil prices and the resulting increase in 

governmental support programs for renewable energy 

enterprises.

Figure 2. Full season growth of Elephantgrass near 

Gainesville, FL. Credits: Forage Extension, Agronomy 

Department, UF/IFAS.

Biology of Elephantgrass 

Elephantgrass is an erect, perennial bunchgrass 

with large stiff stems at maturity. Although dwarf and 

intermediate strains exist, tall-growing selections 

produce the highest biomass yield when allowed to 

grow the entire warm growing season. From April 

through October, the coarse stems increase in length 

and weight, accumulating dry matter up to 18 feet 

above the ground. Spike (cattail) seed heads emerge 

from late October through November for most 

selections. Seeds are small, quickly lose viability, and 

are genetically diverse; therefore elephantgrass is 

propagated vegetatively. 

Production 

While the highest production has been reported 

on moderately-drained, lowland soils, elephantgrass 

is drought tolerant and can produce high yields on 

excessively-drained, deep sands. Though clump 

sections can be dug and used for propagation, it is 

primarily propagated with 3- to 4- node (bud) pieces 

cut from the hardened portion of the stalk. Pieces 

planted horizontally in furrows should be covered 

with no more than 2 to 3 inches of soil. Three-node 

stalk pieces can also be placed into the soil at a 45 

degree angle with the uppermost node exposed. To 

produce quality planting material, nurseries should be 

fertilized in the spring with a minimum of 300 lb of 

N per acre. Phosphorus and potassium should be 

applied based on soil test. For northern Florida, stalk 

pieces can be planted in August or from late October 

until the first killing freeze. When planted in the 

summer, elephantgrass should be allowed to 

accumulate biomass without harvest throughout the 

remaining growing season to ensure winter survival. 

The planting time is less critical, though, for southern 

Florida. In both cases, the seedbed should be 

thoroughly prepared. and rows should be 3 to 5 feet 

apart. For large operations, machinery used to plant 

sugarcane stalk pieces can be adapted for 

elephantgrass. Both summer and fall plantings can be 

harvested for biomass during the following growing 

season.

Figure 3. Hardened stalks of elephantgrass used for 

propagation. Credits: Forage Extension, Agronomy 

Department, UF/IFAS.

Potential Yields 

In north-central Florida, the highest dry biomass 

yields have exceeded 20 ton/acre/year. Average 

production for full-season elephantgrass should range 

from 14 to 18 ton/acre. Yield depends greatly on the 

amount and distribution of rainfall and fertilization 

rate. For full-season growth, elephantgrass should be 

fertilized with 200 to 300 lb of N per acre in the 

spring in two split applications. Elephantgrass can 

also be harvested twice yearly. Annual yield will 
Production of Biofuel Crops in Florida: Elephantgrass 3

generally be 10 to 20% lower with two harvests, but 

the biomass will be more easily converted to methane 

or ethanol. For two harvests per year, apply 150 lbs 

of N per acre in the spring and 150 lbs of N after the 

first harvest. 

Production Challenges 

Major production challenges are the initial 

expense of establishment and the high N rates needed 

to produce heavy biomass tonnage. The cost of 

establishment can be reduced somewhat by 

mechanizing planting operations. By using alternative 

nutrient sources (e.g., biosolids, livestock manures, 

and industrial byproducts), the high cost of chemical 

fertilizers could also be reduced. 

Estimated Production Costs

In 2003, the total variable cost to establish one 

acre of elephantgrass with hand labor was estimated 

to be $530 (see Energy from Crops: Production and 

Management of Biomass/Energy Crops on Phosphatic 

Clay in Central Florida at 

http://edis.ifas.ufl.edu/EH213
). This estimate 

included a fertilization N rate of 200 lb/acre using 

ammonium nitrate. While a higher cost can be 

expected at the time of this writing, it should be noted 

that establishment costs can be amortized over the 

life of the stand. With established stands, major 

production costs include fertilization and harvesting. 

Environmental Concerns

As with all crops that require N fertilization and 

are grown on Florida's sandy soils, nitrate leaching is 

an environmental concern. Also, elephantgrass is 

currently on the “do not plant” list for South 

Florida due to its potential for invasiveness, but it can 

currently be planted in Central and North Florida. 

Invasive potential among improved elephantgrasses 

in North Florida has not yet been observed, but this 

issue requires further study.

Summary

Elephantgrass is the highest yielding, best 

adapted perennial grass for biomass production in 

Florida. Currently, however, there are no commercial 

facilities converting elephantgrass to bioenergy, so 

planting for bioenergy purposes cannot be 

recommended.

Sources of Additional Information

• Biomass co-firing with coal at Lakeland, 

Florida, utilities 

http://trees.ifas.ufl.edu/

BioEnergy98%20Paper.pdf

• 
New Forage, Grain, and Energy Crops for 

Humid Lower South, 

US

http://www.hort.purdue.edu/newcrop/

proceedings1999/v4-060.html


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