ECOLOGICALLY-BASED SOIL MANAGEMENT FOR SUSTAINABLE AGRICULTURE AND RESOURCE CONSERVATION
Title: Fluid Fertilizer's Role in Sustainng Soils Used for Bio-Fuels Production
Submitted to: Fluid Fertilizer Foundation Symposium Proceedings
Publication Type: Proceedings
Publication Acceptance Date: February 19, 2008
Publication Date: February 19, 2008
Citation: Kovar, J.L., Karlen, D.L. 2008. Fluid Fertilizer's Role in Sustainng Soils Used for Bio-Fuels Production. In: Fluid Fertilizer Foundation Symposium Proceedings. Fluid Fertilizer Forum, February 17-19, 2008, Scottsdale, AZ. 2008 CDROM.
Interpretive Summary: Growing crops for bio-fuels production has attracted the attention of many producers – especially in the Corn Belt states. Both corn grain and stover are being evaluated as potential bio-fuel feedstocks. Unfortunately, our understanding of the short- and long-term effects of removing both corn grain and stover on soil nutrient cycling, physical properties, and biological activity is limited. With a field study, we evaluated the performance of several sulfur (S) fertilizers as S sources for corn grown for bio-fuels in Iowa. After two 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 10 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-fuels. The results of this research will benefit commercial growers and both the fertilizer and ethanol industries by providing nutrient management guidelines that maximize crop utilization and biomass yields.
The short- and long-term effects on soil nutrient cycling, physical properties, and biological activity of striving for higher grain yields and removing crop residues for bio-fuels production must be understood to provide more quantitative crop and soil management guidelines. Studies focusing on tillage, fertilizer rates and placement, cover crops, and other management questions are needed. Recognizing the difficulty in addressing all of these variables in a single project, this study focuses on potassium (K) and sulfur (S) requirements of no-till corn (Zea mays L.) grown for a bio-fuels study. Our objectives for 2007 were to: i) evaluate the performance of several S fertilizers, including liquid ammonium thiosulfate (12-0-0-26S), as S sources for corn grown in Iowa, ii) complete analyses of field and laboratory data from 2006, and iii) initiate a comprehensive tillage, nutrient management, crop residue removal, and cover crop study. Field trials conducted in 2006 and 2007 targeted low organic matter soils found on eroded hill slopes. Plots established in 2006 on a Clarion loam showed that applying 30 lb S/A increased mean plant dry weight and whole-plant S concentrations at the V5 growth stage. By mid-silk, however, S concentrations were below the sufficiency range of 0.21% to 0.50%, even when S fertilizer had been applied. Consequently, corn yield was not increased and grain moisture at harvest was not reduced by S fertilizer application. No one S fertilizer source statistically outperformed the others, although 30 lb S/A applied as 13-33-0-15S increased grain yield 7 bu/A compared with the control. On a Clarion silt loam in 2007, application of 30 lb S/A once again increased mean plant dry weight and whole-plant concentrations of S at V5, but by mid-silk, S concentrations were again below the sufficiency range. This time, application of 30 lb S/A as either 13-33-0-15S or 21-0-0-24S increased yield by more than 10 bu./A compared with the control, a difference significant at p=0.08. Below-normal precipitation during part of each growing season and significant soil variability at both sites presumably minimized the statistical response to S fertilizer. However, for several reasons, including erosion of hill slopes, fewer S impurities in fertilizer materials, 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-fuels.