Switchgrass nitrogen response and estimated production costs on diverse sites

Abstract

Switchgrass (Panicum virgatum L.) has been the principal perennial herbaceous crop investigated for bioenergy production in North America given its high production potential, relatively low input requirements, and potential suitability for use on marginal lands. Few large trials have determined switchgrass yields at field scale on marginal lands, including analysis of production costs. Thus, a field-scale study was conducted to develop realistic yield and cost estimates for diverse regions of the USA. Objectives included measuring switchgrass response to fertility treatments (0, 56, and 112 kg N ha À1 ) and generating corresponding estimates of production costs for sites with diverse soil and climatic conditions. Trials occurred in Iowa, New York, Oklahoma, South Dakota, and Virginia, USA. Cultivars and management practices were site specific, and field-scale equipment was used for all management practices. Input costs were estimated using final harvest-year (2015) prices, and equipment operation costs were estimated with the MachData model ($2015). Switchgrass yields generally were below those reported elsewhere, averaging 6.3 Mg ha À1 across sites and treatments. Establishment stand percent ranged from 28% to 76% and was linked to initial year production. No response to N was observed at any site in the first production year. In subsequent seasons, N generally increased yields on well-drained soils; however, responses to N were nil or negative on less well-drained soils. Greatest percent increases in response to 112 kg N ha À1 were 57% and 76% on well-drained South Dakota and Virginia sites, where breakeven prices to justify N applications were over $70 and $63 Mg À1 , respectively. For some sites, typically promoted N application rates may be economically unjustified; it remains unknown whether a bioenergy industry can support the breakeven prices estimated for sites where N inputs had positive effects on switchgrass yield.

Switchgrass and Giant Miscanthus Biomass and Theoretical Ethanol Production from Reclaimed Mine Lands

“…Switchgrass and miscanthus productivity were comparable with those on other marginal and reclaimed lands under annual applications of 0-60 kg N ha −1 [15,36,48,51,55]. Annual biomass yields of these species on agricultural soils under limited N rates have ranged from 2.5 to 16.0 Mg DM ha −1 for switchgrass [6,15,27,[56][57][58][59] and from 11.9 to 34.6 Mg DM ha −1 for miscanthus [5,27,59]. On marginal land, annual yields with < 67 kg N ha −1 have ranged from 2.0 to 19.0 Mg DM ha −1 for switchgrass [5,6,11,15,16,49,54,55].…”

“…Annual biomass yields of these species on agricultural soils under limited N rates have ranged from 2.5 to 16.0 Mg DM ha −1 for switchgrass [6,15,27,[56][57][58][59] and from 11.9 to 34.6 Mg DM ha −1 for miscanthus [5,27,59]. On marginal land, annual yields with < 67 kg N ha −1 have ranged from 2.0 to 19.0 Mg DM ha −1 for switchgrass [5,6,11,15,16,49,54,55]. On fertile WV mine soils, DM production in the seventh year of growth was 10.0 and 19.0 Mg DM ha −1 , respectively, for switchgrass cultivars Shawnee and Cave-In-Rock [14].…”

“…The most widely produced biofuel is from maize (corn; Zea mays L.) grain conversion to ethanol. Increasing world food demands may constrain availability of agricultural land for bioenergy production from corn grain [3][4][5][6]. An annual crop with large soil nutrient requirements and risks of soil erosion and runoff that is cultivated primarily on productive agricultural lands, corn may be less well suited than herbaceous perennials for fuel production [7][8][9][10][11].…”

Spatial agent‐based modeling for dedicated energy crop adoption and cellulosic biofuel commercialization

“…This assumption is realistic because Indiana has similar soil, precipitation, and climate conditions to those in Iowa (no switchgrass yield data currently exist for Indiana). The average cost of switchgrass production is estimated to be $694.5 ± 48.2 ha −1 at a nitrogen fertilization rate of 112 kg ha −1 . The corresponding average yield of switchgrass is calculated to be 9.0 t ha −1 .…”

Microtopography‐induced transient waterlogging affects switchgrass (Alamo) growth in the lower coastal plain of North Carolina, USA

“…Previous studies have investigated growth responses of various ecotypes of switchgrass to several nonwater-related stresses, such as salinity (Kim et al, 2012;Anderson et al, 2015;Hu et al, 2015), nutrients (Ma et al, 2001;Stroup et al, 2003;Heaton et al, 2004;Arundale et al, 2014;Liu & Basso, 2016;Fike et al, 2017), high temperature (Knapp, 1985;Hartman & Nippert, 2013), and low temperature (Cordero & Osborne, 2017). With respect to water stress, switchgrass, especially upland cultivars, has been believed to be drought tolerant (Sanderson & Reed 2000;Heaton et al, 2004;Hartman et al, 2012) because of its high capability to develop deep root systems under dry conditions.…”