Panicum Virgatum - Establishment and Management

Establishment and Management

Switchgrass can be grown on land considered unsuitable for row crop production, including land that is too erodible for corn production, as well as sandy and gravelly soils in humid regions that typically produce low yields of other farm crops. No single method of establishing switchgrass can be suggested for all situations. The crop can be established both by no-till and conventional tillage. When seeded as part of a diverse mixture, planting guidelines for warm-season grass mixtures for conservation plantings should be followed. Regional guidelines for growing and managing switchgrass for bioenergy or conservation plantings are available. Several key factors can increase the likelihood of success for establishing switchgrass. These include:

• Planting switchgrass after the soil is well warmed during the spring.
• Using seeds that are highly germinable and planting 0.6 - 1.2 cm deep, or up to 2 cm deep in sandy soils.
• Packing or firming the soil both before and after seeding.
• Providing no fertilization at planting to minimize competition.
• Controlling weeds with chemical and/or cultural control methods.

Mowing and properly labeled herbicides are recommended for weed control. Chemical weed control can be used in the fall prior to establishment, or before or after planting. Weeds should be mowed just above the height of the growing switchgrass. Hormone herbicides, such as 2,4-D, should be avoided as they are known to reduce development of switchgrass when applied early in the establishing year. Plantings that appear to have failed due to weed infestations are often wrongly assessed, as the failure is often more apparent than real. Switchgrass stands that are initially weedy commonly become well established with appropriate management in subsequent years. Once established, switchgrass can take up to three years to reach its full production potential. Depending on the region, it can typically produce 1/4 to 1/3 of its yield potential in its first year and 2/3 of its potential in the year after seeding.

After establishment, switchgrass management will depend on the goal of the seeding. Historically, most switchgrass seedings have been managed for the Conservation Reserve Program in the US. Disturbance such as periodic mowing, burning, or disking is required to optimize the stand’s utility for encouraging biodiversity. Presently, increased attention is being placed on switchgrass management as an energy crop. Generally, the crop requires modest application of nitrogen fertilizer, as it is not a heavy feeder. Typical nitrogen (N) content of senescent material in the fall is 0.5% N. Fertilizer nitrogen applications of about 5 kg N/hectare (ha) applied for each tonne of biomass removed is a general guideline. More specific recommendations for fertilization are available regionally in North America. Herbicides are not often used on switchgrass after the seeding year, as the crop is generally quite competitive with weeds. Most bioenergy conversion processes for switchgrass, including those for cellulosic ethanol and pellet fuel production, can generally accept some alternative species in the harvested biomass. Stands of switchgrass should be harvested no more than twice per year, and one cutting often provides as much biomass as two. Switchgrass can be harvested with the same field equipment used for hay production, and it is well-suited to baling or bulk field harvesting. If its biology is properly taken into consideration, switchgrass can offer great potential as an energy crop.