# Growing and Harvesting Switchgrass for Ethanol Production in Tennessee

Clark D. Garland, Professor, Agricultural Economics Chair, Biofuels Farmer Education Team * 

# S witchgrass is a warm-season perennial grass native to North America. The plant can reach heights up to 10 feet with an extensive root system. Once estab

lished, switchgrass well-managed for biomass should have a produc

tive life of 10-20 years. Within the stand, switchgrass is an extremely strong competitor. However, it is not considered an invasive plant. Switchgrass adapts well to a variety of soil and climatic conditions. It is most productive on moderately well to well-drained soils of medium fertility and a soil pH at 5.0 or above. The high cellulosic content of switchgrass makes it a favorable feedstock for ethanol production. It is anticipated that switchgrass can yield sufficient biomass to produce approximately 500 gal

lons of ethanol per acre. While the Tennessee Biofuels Initiative includes a demonstration plant to make ethanol from switchgrass, the market for switchgrass as an energy crop remains limited. Producers will likely need to be located within 30 to 50 miles of a cellulosic etha

nol plant. Producing switchgrass for energy generally occurs under some form of contractual arrangement with the end-user. To reap potential benefits from using switchgrass for cellulosic ethanol production, the system of production must be profitable for farmers and energy producers, as well as cost effective for consumers. 

## Recommended Varieties There are two main types of switchgrass. The upland varieties usually grow 5 to 6 feet tall and are adapted to the Midwest. Lowland varieties are most adapted for the South and grow from 7 to 10 feet tall. The most common lowland varieties adapted to Tennessee are Alamo and Kanlow and both are currently recommended by UT. Alamo has been used in the major

ity of recent research conducted by the University of Tennessee on switchgrass for biomass. Henry County Extension Director, Ken Goddard (at left), discusses switchgrass production with farmers. SP701-A 

# UT Biofuels Initiative

## Recommended Seeding Rate Switchgrass seed is very small and much of it will not germinate right after it is harvested. However, aging, treating with water and chill

ing temperatures (stratification) or storing it in warm conditions will break dormancy. When establishing switchgrass, buying quality seed is an important consideration. Switch

grass seed are normally sold on the basis of pure live seed (PLS). The germination rate will vary. There

fore, it is critical to plant according to the PLS. In calibrating seeding equipment, take into account the percentage of pure seed and the germination rate. UT recommends 6 pounds of PLS per acre.



## Fertilizer and pH Recommendations Although switchgrass is adapted to nutrient-deficient soils, soil fertility is important and soil test

ing is recommended to determine pH and nutrient availability. If soil test values are medium or high in phosphorous (P) and potassium (K), no additional P205 or K20 is recom

mended. If the soil test is low in P, an annual application of 40 pounds of P205 per acre is recommended. If the soil is low in K, an annual appli

cation of 80 pounds of K20 should be applied per acre. If the soil pH is 5.0 or above, no lime is recom

mended. These recommendations are for long-term reasonable yields of switchgrass for biomass, with switchgrass harvested after a kill

ing frost over a period of 10 years. Being a perennial, switchgrass is thought to translocate much of the aboveground nutrients back into the crown root system, resulting in very low input needs after establishment. Nitrogen should not be applied until the stand is established and weeds controlled. In the first year, do not apply nitrogen. It increases competition from annual grasses and broadleaf weeds. Beginning in the spring of the second year, 60 pounds of nitrogen per acre are recommended (Table 1).


## Planting Date Planting dates can range from late April to mid June. Switchgrass is a warm-season grass and estab

lishes and grows best under warm conditions.


## Planting Methods Switchgrass can be planted into a tilled seedbed or no-tilled. It appears no-till planting with a no-till drill in fields not bedded from past row crops is the ideal way to plant. Switchgrass should be planted when sufficient soil moisture is available for emergence of the seeds. A planting depth of 1⁄4 to no deeper than 1⁄2 inch is criti

cal with good seed coverage at that 

### Table 1. Soil Test Recommendations for Establishment and Maintenance of Switchgrass for Biomass

Practice Nitrogen Phosphate (P 2 

### O 5

### ) Potash (K2

### 0)

Soil Test Levels *



### (NT) L M H L M H

1. Establishment Year 0 40 0 0 80 0 0

2. Maintenance Year 60 40 0 0 80 0 0

* 

### NT = Not Tested L = Low M = Medium H = High Alamo Switchgrass seeds are quite small with more than 400,000 seeds per pound. 

# UT BiofuelsInitiative 2depth. This is usually easier to achieve in no-tilled soil conditions. The drill should have small seed boxes suitable for accurately meter

ing switchgrass.



## Weed Control In the establishment year, switchgrass does not compete well with grasses such as fescue, crabgrass, johnsongrass, etc. and broadleaf weeds. Appropriate weed control measures vary greatly according to previous cropping history and specific weed varieties. Carefully evaluate fields before and after planting and check with an Extension agent for control options. Few herbicides are labeled for weed control in switchgrass on non-Conservation Reserve Program (CRP) land in Tennessee. Therefore, it is critical to control weeds prior to planting. Most often, a glypho

sate herbicide (e.g., Roundup ®

, Gly-4 Plus ® ) is used to kill existing cover. The guideline switchgrass budgets include two burndowns with a glyphosate herbicide. The preferred method to establish switchgrass in a pasture or hay field is to spray in the fall prior to plant

ing with a glyphosate herbicide. Before the sod is sprayed, the field should be grazed, mowed or hayed and regrowth allowed to reach 6 to 10 inches. This ensures the herbi

cide comes into contact with an actively growing plant. Cimarron ® , formerly named Ally ®from DupontTM, is labeled for post-emergence application on switchgrass for control of broadleaf weeds. Efforts are currently being made to gain regulatory approval for the use of an additional herbicide for grass suppression in Tennessee. Observations in Tennessee on weed control in switchgrass indicate grass competition is much more severe than broadleaf compe

tition. Once switchgrass is wellestablished and properly managed, it is very competitive against weeds. Month-old switchgrass in East Tennessee.

Conventional equipment can be used to harvest switchgrass. Large rectangular bales are easier to handle, store and transport.



## Reseeding Switchgrass Switchgrass establishment will not always be successful in the first year. Weed pressure, seed quality, incorrect planting procedures, level of soil moisture within the first four to five weeks of planting and other factors can contribute to not achieving an acceptable stand of switchgrass. The expected prob

ability of needing to reseed is as

sumed to be 20 percent. Guideline expenses for establishment include the reseeding costs. 

## Harvesting Switchgrass can be harvested as a one- or two-cut system. When cut twice, the first cutting would occur when switchgrass is in late boot to very early seedhead emer

gence, which is usually in late June or early July. The second cutting would be at the end of the season and can occur when the plant goes into dormancy (usually after the first killing frost). In the one-cut system, the switchgrass is harvested once after 

# UT BiofuelsInitiative 3Programs in agriculture and natural resources, 4-H youth development, family and consumer sciences, and resource development. University of Tennessee Institute of Agriculture, U.S. Department of Agriculture and county governments cooperating. UT Extension provides equal opportunities in programs and employment. SP701A-5M-5/08 (Rep) R12-4110-070-019-08 08-0120 For more information about the UT Biofuels Initiative, please visit http://www.UTbioenergy.org * Developed by Biofuels Farmer Education Team: Gary E. Bates, Christopher D. Clark, Deloras A. Dalton, Delton C. Gerloff, John J. Goddard, Ken J. Goddard, Laura Howard, Patrick D. Keyser, Melvin A. Newman, David R. Perrin, Lawrence E. Steckel, Finis Stribling, Donald D. Tyler, Michael D. Wilcox and James B. Wills, Jr. November 1 or the first killing frost, whichever comes first. Total biomass yield for the year is simi

lar in the one- and two-cut system. The choice should be influenced by management timing, costs and needs of the buyer relative to cut

ting time. Single harvest of switch

grass after the aboveground growth is killed by frost will reduce nutri

ent removal and fertility needs. Switchgrass should be cut at least 6 inches high. The taller stubble will help reduce punctured tires by allowing equipment tires to push over the stubble. Furthermore, switchgrass stand survival, vigor and yield consistency in later years is greatly impacted by the cutting time and height. Switchgrass can be harvested with conventional hay equipment. Many farmers have large round balers and prefer to use their existing equipment. Round bales are acceptable. However, large rectangular bales (3 x 4 x 8 feet and 4 x 4 x 8 feet) are easier to handle, store and transport.



## Yields In test plots, switchgrass has frequently produced more than 10 tons of dry matter per acre/per year. However, on a commercial scale, it is more reasonable to expect 6 to 8 tons per acre. In the first year of production, yields are estimated to run 30 percent (2 tons) of the full yield potential. Second year yield is normally 70 percent (5 tons) of full

Factsheet adapted from publications developed by the University of Tennessee, Iowa State and Auburn University. production. In the third year, yields should be at the 100 percent yield level of 7 tons. Over the first 5 years of an anticipated contract period, yields are estimated to average 5.5 tons per year. Obviously, land qual

ity, weather conditions, stand vigor, weeds and overall management will impact yield levels for a given switchgrass field.


## Pest and Disease Management Switchgrass has resistance to a wide variety of insects and diseases. Researchers and farmers have not experienced significant insect and disease problems in switchgrass trials conducted in Tennessee. As switchgrass acreage expands, it is not unreasonable to expect prob

lems to develop over time.

Visit the UT Extension Web site at http://www.utextension.utk.edu/ Funding that allowed the development of many of these recommendations was provided by the U.S. Department of Energy through project GO14219. 

# UT BiofuelsInitiative 4

Biofuels Initiative