Switchgrass production in the central claypan region of Missouri

Abstract

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT REQUEST OF AUTHOR.] Severe soil erosion across the Central Claypan Region of Missouri has been correlated with low productivity as the depth to the claypan horizon decreases. Transitioning from annual to perennial cropping systems is expected to improve water quality and reduce soil erosion and runoff volume. Objectives of this study were to determine the relationship between topsoil depth and switchgrass plant density during establishment; simulate corn and switchgrass production and project switchgrass yield potential on claypan soils with the ALMANAC model; and develop a comparative breakeven analysis for switchgrass and corn-soybean cropping systems. Plant density data were collected from research plots with varying topsoil depths following emergence. Average switchgrass plant densities met or exceeded the threshold indicative of successful establishment for bioenergy production. Results indicate successful establishment is achievable across varying topsoil depths with limited risk for post-establishment yield reduction. Corn yield data for the claypan region and switchgrass data from plot studies were simulated with the ALMANAC model. Simulation of county corn yields and switchgrass plot yields provided excellent regression estimates. Projections suggest claypan soils can produce 9-14 Mg ha[superscript -1] depending on the variety. Comparative breakeven prices for switchgrass ranged from a low of $65 Mg[superscript -1] on top soil [less than] 15 cm to a high of $124 Mg[superscript -1] on top soil [greater than] 27 cm. These results suggest ALMANAC is capable of simulating average yields for corn and switchgrass across the Central Claypan Region and switchgrass production can compete economically with annual grain crops on eroded soils with yield and price points as low as 12.5 Mg ha[superscript -1] and $65 Mg[superscript -1], respectively.--From public.pdf