ARS | Publication request: Comparative breakeven analysis of annual grain and perennial switchgrass cropping systems

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 19, 2012
Publication Date: February 29, 2012
Citation: Landers, G.W., Thompson, A.L., Kitchen, N.R., Massey, R.E. 2012. Comparative breakeven analysis of annual grain and perennial switchgrass cropping systems. Agronomy Journal. 104: 639–648. DOI: 10.2134/agronj2011.0229.

Interpretive Summary: Some soils in the U.S. Midwest region have been especially negatively impacted by grain cropping. The result has been lost productivity and diminished resiliency for ecosystem function. Of note are the degraded soils of the Midwest classed as “claypan soils.” These soils are disproportionate sources of non-point pollution when grain cropped. Alternative production systems are needed for long-term productivity and environmental sustainability. Because of year-to-year fluctuations in grain yield caused by water stress on these soils, they may have potential for conversion from grain to more stable-yielding grass production in support of biomass energy markets. This study was conducted to examine the economic potential of changing from grain crops to perennial switchgrass production on claypan soils. Comparative breakeven prices (i.e., market price needed for switchgrass to match the revenue of corn/soybean production) for two switchgrass varieties ranged from $72/ton on marginal, eroded soils to $137/ton on soils with about a foot of topsoil. Breakeven switchgrass yields (i.e., yield needed for switchgrass to match the revenue of corn/soybean production) with a price of $44/ton would require yield increases of up to 450% over typical yields for lower-yielding varieties. The switchgrass variety Kanlow holds the most promise for biomass production on claypan soils. With an average projected yield of 5.6 ton/acre, breakeven prices fall to around $66-$88/ton for soils with less than 6 inches of topsoil. Based on these projections perennial switchgrass can compete with conventional grain crops at reasonable yield levels on eroded soils for the Central Claypan Region. The outcomes of this research help provide information and tools for targeting switchgrass production to degraded claypan landscapes. For these landscapes, farmers are in need of more sustainable land management choices. Bioenergy production opportunities offer the potential for revitalized rural communities. As switchgrass bioenergy markets develop, the knowledge gained from this research will reduce the uncertainty of the decision process, and thereby advance producer adoption.

Technical Abstract: The Central Claypan Region is an important agricultural production region in the U.S. Midwest. However, because of the tendency for grain yield fluctuations caused by water stress, claypan soils may have potential for conversion from grain to grass production in support of biomass energy markets and conservation programs. This study examines the economic potential of transitioning from grain crops to perennial switchgrass production on claypan soils using comparative breakeven analysis. Partial budgets for a corn-soybean rotation and a perennial switchgrass cropping system were developed. Yield data from research plots with varying topsoil depths and underlying claypan layer were used to establish yield expectations as affected by topsoil depth. Switchgrass yield projections for the claypan region were simulated with the ALMANAC (Agricultural Land Management Alternatives with Numerical Assessment Criteria) model. Comparative breakeven prices for two switchgrass varieties ranged from $65 on marginal, eroded soils to $124/Mg on soils with >27 cm of topsoil. Breakeven yields with a biomass price of $40/Mg would require yield increases of up to 450% for lower yielding varieties. The switchgrass variety Kanlow holds the most promise for biomass production on claypan soils; with an average projected yield of 12.56 Mg/ha, breakeven prices fall to around $60-$80/Mg for marginal soils with less than 15 cm of topsoil. Based on these projections perennial switchgrass can compete with conventional grain crops at reasonable yield levels on eroded soils in the Central Claypan Region.