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United States Department of Agriculture

Agricultural Research Service

Research Project: Improving bioenergy and forage plants and production systems for the central U.S.

Location: Wheat, Sorghum and Forage Research

Title: Switchgrass nitrogen response and estimated production costs on diverse sites

Author
item Farris, Rodney
item Fike, John
item Hansen, Julie
item Heaton, Emily
item Mayton, Hillary
item Mitchell, Robert - Rob
item Owens, Vance
item Pease, James
item Viands, Don

Submitted to: Global Change Biology Bioenergy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/1/2017
Publication Date: 4/25/2017
Publication URL: http://handle.nal.usda.gov/10113/5763097
Citation: Farris, R.L., Fike, J.H., Hansen, J.L., Heaton, E.A., Mayton, H.S., Mitchell, R., Owens, V.N., Pease, J.W., Viands, D.R. 2017. Switchgrass nitrogen response and estimated production costs on diverse sites. Global Change Biology Bioenergy.12444 Availale: http://onlinelibrary.wiley.com/doi/10.1111/gcbb.12444/full.

Interpretive Summary: Switchgrass has been the principal perennial herbaceous crop investigated for bioenergy production in North America. High productivity, adaptability to marginal sites, and low requirements for nutrient inputs make switchgrass desirable for limited-input bioenergy systems. Few multi-location field-scale trials have determined switchgrass yields and production costs on marginal lands. Our objectives were to develop realistic yield and production cost estimates for diverse regions of the USA, including measuring switchgrass response to fertility treatments (0, 50, and 100 lb N acre-1). Field-scale trials occurred in Iowa, New York, Oklahoma, South Dakota, and Virginia, USA, with site-specific cultivars and management practices. Input costs were estimated using 2015 harvest-year prices, and equipment operation costs were estimated with an agro-economic model. Switchgrass yields generally were below those reported elsewhere, averaging 2.8 US tons acre-1 across sites and treatments. Establishment stand percent ranged from 28 to 76% and was positively linked to initial productivity. Nitrogen fertilizer generally increased yields on well-drained soils, but responses to N were limited on less well-drained soils. Greatest mean percent increases in response to 100 lb N acre-1 (vs. 0 N) were 57 and 76% at well-drained sites in South Dakota and Virginia where breakeven prices for N applications were over $63 and $57 ton 1, respectively. For some sites, typically-promoted N fertilizer rates may not be economically justified. It is uncertain whether a bioenergy industry can support the breakeven prices estimated for sites where N inputs had positive effects on switchgrass yield.

Technical 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-1) 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. Switchgrass yields generally were below those reported elsewhere, averaging 6.3 Mg ha-1 across sites and treatments. Establishment stand percent, ranging from 28 to 76%, was positively linked to initial productivity. No response to N was observed at any site 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 mean percent increases in response to 112 kg N ha-1 (vs. 0 N) were 57 and 76% at well-drained South Dakota and Virginia sites, where, breakeven prices to justify N applications were over $70 and $63 Mg 1, 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.

Last Modified: 09/25/2017
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