What is switchgrass

Switchgrass is unquestionably one of the best crops for carbon sequestration. When above-ground switchgrass is harvested and burned for energy, carbon dioxide is once again returned to the atmosphere from where it was originally obtained by the plant.

However, if it replaces the use of nonrenewable fossil fuel, that essentially only adds carbon to the atmosphere. In this way, carbon dioxide is recycled by the use of switchgrass for energy production, making this process carbon-dioxide-neutral or actually carbon-dioxide-negative if soil carbon sequestration is considered , compared to fossil fuel use that continually adds carbon dioxide to the atmosphere.

When compared to low-grade coal, burning switchgrass for energy will probably result in less toxic atmospheric emissions, with few, if any, of the various sulphur- and nitrogen-oxide pollutants associated with coal combustion. Most switchgrass research has been centered in the prairie states of the Midwestern United States and the prairie provinces of Canada.

Roger Samson of McGill University has extensively written on the Canadian government's proposal to replant million acres of tall grass prairie, mostly to switchgrass to be used for ethanol production.

This project would replace all of Canada's gasoline requirements; reduce government subsidies to both the agriculture and energy sectors; save farms and create rural employment opportunities; prevent Canada from becoming a net oil importing nation; rehabilitate prairie soils and wildlife populations; and reduce Canadian CO2 emissions by 15 percent. This project is commonly known as "Solar Battery for the Prairies.

Additionally, the ash content of switchgrass, either as raw biomass or as fuel pellets, can be further reduced by allowing the switchgrass to over-winter in the field. Natural leaching reduces the silica and chloride contents in this material. Agronomic research has shown that ash content may be reduced by producing switchgrass in sandy soils as opposed to clay soils due to their silica and chloride contents ; cultivar choice also can strongly influence combustibility and ash content.

The genetic variability of switchgrass for bio-energy and bio-energy and cattle-grazing co-production systems, whether fuel pellets for combustion or as a source for cellulosic-ethanol production, still poses some challenges to researchers and those interested in developing this crop. Switchgrass cultivars are highly variable, and agronomic research, and perhaps genetic engineering, to develop improved varieties can assist stand establishment, productivity and decrease unwanted nutritional toxins that impact grazing and decrease unwanted combustion products.

Early production-improvement trials have demonstrated that a single cross between two cultivars could increase biomass yields by a very significant 8. This study examined estimated cellulosic-ethanol production costs and yields. The authors concluded that switchgrass had the potential to produce greater ethanol yields per acre than corn when both the grain and corn stover were used for cellulosic-digestion processing.

Average ethanol yields estimated to be gallons per acre at a conversion rate of 79 gallons per U. Market Trends Canada is ahead of the United States in developing switchgrass as a biofuel. Producing switchgrass pellets for use in decentralized home heating systems is well developed, and pellet stoves are briskly selling to individual homeowners as supplemental heating sources.

These are similar to the "corn stoves" that burn waste or surplus corn or wood-waste pellets sold in the United States. He developed an economic analysis based on production in different soil types over a number of years. This placed the cost of switchgrass pellets at 50 percent of conventional fuels for rural consumers.

It was estimated at the time that off-farm energy consumers in agricultural regions could expect switchgrass to save them about 30 percent on their bills compared to oil. Bulk handling systems were and are available to provide consumer convenience similar to that of fossil fuels.

Switchgrass pellets have been observed to produce in the size of In comparison, wood has been reasoned as producing The long-term prospects for biofuels as an energy source certainly need to consider the economic value for the alternatives in the energy market. Based on several prior years energy cost data, the researchers compared switchgrass pellets to natural gas.

Development of any new market also presents other opportunities. The researchers concluded that prairie agriculture bio-fuel production also would promote interest in developing fiber production, storage and marketing systems that could produce material for industrial and consumer products. Both in America and Europe it can be found as an ornamental plant. The grass is also found in South America and Africa where it is used as a forage crop.

Switchgrass is a perennial C4 grass propagated by seed that can be established at low cost and risc and requires very low inputs while giving high biomass yields even on marginal soils. Ask the Editors 'Everyday' vs. What Is 'Semantic Bleaching'? How 'literally' can mean "figuratively". Literally How to use a word that literally drives some pe Is Singular 'They' a Better Choice? The awkward case of 'his or her'.

Take the quiz. If switchgrass is planted after crops that leave heavy residue such as corn or sorghum Sorghum bicolor , it may be necessary to graze the residue, shred or bale the stalks, or use tillage to reduce the residue. If tillage is required, the seedbed needs to be packed to firm the soil. The packed soil needs to be firm enough so that walking across the field leaves only a faint footprint Figure 3. Applying 8 oz of quinclorac plus 1 qt of atrazine per acre immediately after planting has provided effective grassy and broadleaf weed control for establishment.

The most cost-effective method to control broadleaf weeds in switchgrass fields during the establishment year is to apply 2,4-D at 1 to 2 qt acre -1 after switchgrass seedlings have about four leaves. After the establishment year, a successfully established switchgrass stand requires limited herbicide applications. Nitrogen N fertilizer is not recommended during the planting year since N will encourage weed growth, increase competition for establishing seedlings, increase establishment cost, and increase economic risk associated with establishment if stands should fail Mitchell et al.

Soil tests are recommended prior to planting. Since switchgrass is deep rooted, soil samples should be taken from each 1-foot increment to a depth of 5 feet. In most agricultural fields, adequate levels of phosphorus P and potassium K will be in the soil profile.

If warranted by soil tests, P and K can be applied before seeding to encourage root growth and promote rapid establishment. Recommended P levels for the western corn belt are in Table 1. Switchgrass can tolerate moderately acidic soils, but optimum seed germination occurs when soil pH is between 6 and 8 Hanson and Johnson, Table 1.

Phosphorus P recommendations for the western corn belt based on two common soil test levels Anderson and Shapiro, Although switchgrass can survive on low fertility soils, it does respond to fertilizer, especially N.

The amount of N required by switchgrass is a function of the yield potential of the site, productivity of the cultivar, and other management practices being used Vogel et al. Consequently, the optimum N rate for switchgrass managed for biomass will vary, but a few references indicative of the responses to N in different regions of the United States are included Table 2.

Additionally, biomass will decline over years if inadequate N is applied, and yield will be sustainable only with proper N application Muir et al. In Nebraska and Iowa, Cave-in-Rock yield increased as N rate increased from 0 to lb N acre -1 , but soil N increased when more than lb N acre -1 were applied Vogel et al.

They reported biomass was optimized by applying lb N acre -1 , with about the same amount of N being applied as was being removed by the crop. A general N fertilizer recommendation for the Great Plains and Midwest region is to apply 20 lb N acre -1 yr -1 for each ton of anticipated biomass if harvesting during the growing season, with N rate reduced to 12 to 14 lb N acre -1 yr -1 for each ton of anticipated biomass if harvesting after a killing frost.

The N rate can be reduced when the harvest is after a killing frost because switchgrass cycles some N back to roots during autumn. If soil tests indicate a new switchgrass field has high residual N levels, N rates can be significantly reduced during the initial production years using the above information as a guideline. Apply N at switchgrass green-up to minimize cool-season weed competition. Table 2.

Switchgrass publications addressing nitrogen fertilizer application for different regions of the United States listed by state, the major parameters evaluated in the study, and references for each study. Harvest date and N rate effects on biomass, persistence, species composition, and soil organic carbon of switchgrass-dominated CRP.

Spraying herbicides to control broadleaf weeds typically is needed only once or twice every 10 years in an established, well-managed switchgrass stands. When needed, the most effective and economical approach is with broadcast applications of 2,4-D at 1 to 2 qt acre Spray broadleaf weeds as early in the growing season as possible to reduce the impact of weed interference on switchgrass yield.

In some cases, cool-season grasses may invade switchgrass stands and reduce yield. Harvesting after switchgrass senescence in autumn but while cool-season grasses are growing, then applying glyphosate at 1 to 2 qt acre -1 , is an effective method to reduce cool-season grasses.

However, make certain switchgrass is dormant when glyphosate is applied, or stands could be damaged. Spring applications of atrazine at 2 qt acre -1 can be used to control cool-season grasses in established switchgrass stands. Maximizing yield currently is the primary objective when harvesting biomass feedstocks. Sufficient regrowth may occur about one year out of four to warrant a second harvest after a killing frost. Do not harvest switchgrass within six weeks of the first killing frost or shorter than a 4-inch stubble height to ensure translocation of storage carbohydrates to maintain stand productivity and persistence.

Dormant season harvests after a killing frost will not damage switchgrass stands but will reduce the amount of snow captured during winter. In general, a single harvest during the growing season maximizes switchgrass biomass recovery, but harvesting after a killing frost will ensure stand productivity and persistence, especially when drought conditions occur, and reduce N fertilizer requirements.

With proper management, productive stands can be maintained indefinitely and certainly for more than 10 years. Harvesting switchgrass in summer at or after flowering when drought conditions exist is not recommended.

Switchgrass can be harvested and baled with commercially available haying equipment.