Effects of Cover Crop combinations and Fertilizer Application Timing on Nitrogen Leaching

View the project final report

• 2013 annual report

Commodities

• Agronomic: corn, rapeseed, rye, soybeans
• Vegetables: radishes (culinary)

Practices

• Crop Production: conservation tillage
• Education and Training: demonstration
• Farm Business Management: agricultural finance
• Natural Resources/Environment: biodiversity, carbon sequestration, habitat enhancement, soil stabilization
• Production Systems: agroecosystems, holistic management, organic agriculture
• Soil Management: green manures, nutrient mineralization, organic matter, soil analysis, soil chemistry, soil microbiology, soil physics, soil quality/health
• Sustainable Communities: public policy, social capital, sustainability measures

This project is designed to evaluate the economic and environmental benefits to farmers of using cover crops in Central Illinois and the North Central Region. Cover crops have the potential to reduce nitrate leaching from row-crop, tile drained fields common in the region. Cover crop use may allow farmers to reduce nitrate fertilizer applications adding to the profitability of Central Illinois farms. Tile-drained fields in the region have been linked to nitrate pollution in surface waters. Cover crop use may also prevent this pollution improving drinking water quality and making farming more sustainable. The outcomes of this project will be: 1) increased knowledge of cover crop use to Central Illinois farmers, 2) increased adoption of cover crop use by farmers 3) possible reduction of nitrate concentration in surface waters. This project may increase the profitability of farms and reduce the environmental footprint of farming across the North Central Region.

Introduction:

Introduction

      Nitrogen (N) pollution from fertilizer continues to be an environmental issue that threatens row crop agriculture in the Upper Mississippi River Basin. Studies have shown that agriculture fields dominated by tile drained row crop management can cause increased nitrate loss via tile water (Baker, 1975) (Gast, 1978)(Jaynes, 2001)(Dinnes, 2002)(Smiciklas, 2008).   Nitrate loading has impaired drinking water supplies locally in Illinois, making it more expensive to treat and provide safe drinking water to the public.  On a national scale, N loading in the Mississippi River has led to the development of a hypoxic zone (dead zone) in the Gulf of Mexico. Little progress has been made to reduce N loading into the Mississippi River and to the Gulf of Mexico.  One study found that over a ten year period (1998-2008) attempts to reduce N flux into the Mississippi river have not significantly reduced N concentrations (Sprague, 2011).  In Illinois, best management practices (BMPs) such as grassed water-ways, stream buffers, and strip-till farming have been introduced to reduce nutrient loading in surface runoff.   However, these BMPs were found to be ineffective at reducing nitrate concentrations in surface water (Lemke, 2011).  The authors of this study concluded that tile drainage provided a pathway nitrate to bypass surface BMPs and flow directly to waterways.  Nitrate leaching to tile water is a non-point source problem.  Fall applied N (common in Central Illinois) has been shown to leach below the root zone of corn (Hubbard, 1991), where it becomes susceptible to leaching into tile water.  Planting of cover crops offers a non-point source solution, to this non-point source problem.  Cover crop roots can intercept fall applied N that otherwise would percolate below the root zone of corn (Dean, 2009). In the Northeast, forage radish has been shown to reduce nitrate leaching deep in the soil profile.  In theory, cover crop mixtures including forage radish should reduce the amount of nitrate in tile water and escape into the environment.

            The original intent of this project was to evaluate the impact of cover crops and N fertilizer timing on the efficiency of N management in Central Illinois fields.  The original treatments involved multiple cover crop treatments that received nitrogen in the fall and spring.   The treatments included :( Figure 1):

NOTE:  In 2013, the project reported failed cover crop establishment in the projects first year.   Cover crops failed to establish again in the projects second year, despite attempts to modify our cover crop planting methods as described in the 2013 Annual report. As a result cover crop impact was not evaluated as part of this study.   Therefore, the objectives of the project were adjusted and augmented to focus on the nitrogen timing aspect of the project.   

Adjusted Objectives

Objective 1: Compare the impact of fall and Spring N applications across multiple rates on the distribution of soil Inorganic N within the soil profile.

Objective 2: Investigate the impact of N timing and rate on Corn N uptake and grain production in Central Illinois.

Objective 3: Evaluate nitrogen rates and timing for corn production in Central Illinois across multiple on-farm trials.

Bibliography

Baker, J. L., Hanway, J.J.,Johnson, H.P., Campbell, K.L. 1975.  Nitrate, Phosphorus, and Sulfate in Subsurface Drainage Water.

Dean J., Weil R. 2009. Brassica Cover Crops for Nitrogen Retention in the Mid-Atlantic Coastal Plain. Journal of Environmental Quality. 38:520-528.

Dinnes D., Karlen D., Jaynes D, Kaspar T., Hatfield J., Colvin T., Cambardella C. 2002. Nitrogen management strategies to reduce nitrate leaching in tile drained Midwestern soils. Agronomy Journal. 94:153-171.

Gast, R. G., Randal, G.W., Nelson, W.W. 1978. "Nitrate Accumulation in Soils and Loss in Tile Drainage Following Nitrogen Applications to Continuous Corn." Journal of environmental quality 7.2 : 258.

Hubbard, R.K., Johnson, A.W., Leonard, R.A. 1991. “Nitrate transport on sandy coastal plain soil underlain by plinthite.." Transactions of the ASAE 34.3:802.

Jaynes, D.B., Colvin, T.S., Karlen, D.L., Cambardella, C.A., Meek, D.W. 2001. "Nitrate Loss in Subsurface Drainage as Affected by Nitrogen Fertilizer Rate." Journal of environmental quality 30.4 (2001): 1305.

Lemke A., Kirkham K., Lindenbaum T., Herbert M., Tear T., Perry W., Herkert J.  2011. Evaluating Agricultural Best Management Practices in Tile-Drained Subwatersheds of the Mackinaw River, IllinoisJournal of Environmental Quality. 40:1215-1228.

Smiciklas K., Moore A. 2008.a Tile Drainage Nitrate Concentrations in Response to Fertilizer Nitrogen Application. Journal of Agronomy. 7:163-169.

Smiciklas K., Moore A., Adams J. 2008.b Fertilizer Nitrogen Practices and Nitrate Levels in Surface Water within an Illinois Watershed. Journals of Natural Resources and Life Sciences Education. 374:14-19

Sprague L., Hisch R., Aulenbach B.2011. Nitrate in the Mississippi River and Its Tributaries, 1980-2008: Are we making progress? Environmental Science and Technology. 45:7209-7216.

Objectives and Performance Targets

• Objective 1: Compare the impact of fall and Spring N applications across multiple rates on the distribution of soil Inorganic N within the soil profile.

  • Nitrogen application resulted in greater soil inorganic N compared to plots that did not receive N fertilizer. Fall applied N resulted in greater inorganic N in the spring immediately before corn planting, compared to spring N. In contrast, Spring N application resulted in greater inorganic N in the Fall after harvest. With both N timings, there is risk of N loss to the environment. Therefore, there is a need for Midwest farmers to consider N conservation practices when applying N in either the fall or spring.

• Objective 2: Investigate the impact of N timing and rate on Corn N uptake and grain production in Central Illinois.

  • N timing did not have an impact on Corn production. However, at the highest N rate fall applied N resulted in a greater corn N concentration at harvest then spring applied N. Rate of N application did have an impact on Yield. However, the benefit of increasing N rate was not significant after 168 kg N ha-1.

• Objective 3: Evaluate nitrogen rates and timing for corn production in Central Illinois across multiple on-farm trials.

  • On farm trials indicated that nitrogen rate had a greater influence on grain yield then nitrogen timing. However, the optimum N rate varied greatly between experiment sites. This indicates that need for farmers to establish field specific N rates based on local soil conditions.