Submitted to: World Congress of Soil Science
Publication Type: Proceedings
Publication Acceptance Date: February 15, 2010
Publication Date: August 6, 2010
Citation: Kovar, J.L., Karlen, D.L. 2010. Is Sulfur Limiting Maize Grown on Eroded Midwestern U.S. Soils? In: Gilkes, R.J. and Prakongkep, N. (ed). Proceedings of the 19th World Congress Soil Science, August 1-6, 2010, Brisbane, Australia. ISBN 978-0-646-53783-2. DVD. Interpretive Summary: Sulfur (S) is an essential plant nutrient that must be available to corn roots in order to achieve optimum growth of the plant. Our understanding of the effects of removing both corn grain and stover as potential bio-fuel feedstocks on soil S supplies is limited. With a field study, we evaluated the performance of several sulfur (S) fertilizers as S sources for corn grown in Iowa. After three years, we found that an application of 30 lb S/A increased early-season growth and plant S concentrations compared with untreated areas. We also found that S fertilizer increased grain yield by up to 12 bu./A . In addition, below-normal rainfall during part of each growing season and significant soil variability at both research sites probably limited crop response to S. For several reasons including erosion of high-fertility hill slope soils, fewer S impurities in fertilizers, and decreased atmospheric deposition of S throughout the upper Midwest, our results suggest that S may quickly become a limiting nutrient for corn grown to supply bio-fuel feedstocks. The results of this research will benefit both commercial growers and both the fertilizer and ethanol industries by providing nutrient management guidelines that maximize crop utilization and biomass yields.
Technical Abstract: The importance of adequate sulfur (S) for maize (Zea mays L.) production has been recognized for many years and recently confirmed by positive yield responses. We compared a granular S-enhanced fertilizer material [SEF (13-33-0-15S)], granular ammonium sulfate [AMS (21-0-0-24S)], and liquid ammonium thiosulfate [ATS (12-0-0-26S)] on eroded Clarion (Typic Haplaquolls) hill slopes in central Iowa for three years. Applying 34 kg S ha-1 as SEF significantly (P=0.05) increased mean V5 plant dry weight each year. AMS and ATS showed a similar but non-significant trend. Whole-plant S concentrations at V5 were generally higher than the control for all S sources. Grain yield and moisture content at harvest were not affected by S in 2006 and 2007. In 2008, 34 kg S ha-1 as SEF significantly increased yield by 0.76 Mg ha-1. The agronomic efficiency of S (yield per unit applied) was greatest for SEF in 2006 and 2008 (12.3 and 22.5 kg grain (kg S)-1, respectively). Below-normal precipitation during the 2006 and 2007 growing seasons and inherent soil variability presumably affected our S yield response, but overall we conclude that S may become a limiting nutrient for maize, especially if maize stover is harvested as a bio-energy feedstock.