Skip to main content Accessibility help

Use of legume green manures as nitrogen sources for corn production

  • Matt Liebman (a1), Rhonda L. Graef (a2), Daniel Nettleton (a3) and Cynthia A. Cambardella (a4)


Recent volatility in supplies and prices of natural gas and synthetic nitrogen (N) fertilizer suggests a need to develop and refine alternative strategies for supplying N to corn. In this study, conducted in north-eastern Iowa, we examined the use of red clover and alfalfa green manures as means of supplying N to a succeeding corn crop. Red clover intercropped with oat produced significantly more biomass and contained more N than alfalfa intercropped with oat. Tilling green manures in the fall or delaying tillage until the following spring did not have a consistent effect on green manure N content. Without N fertilizer, corn grain yield following oat–red clover and oat–alfalfa was 25–63% greater than following oat grown alone, but at the highest fertilizer rate (202 kg N ha−1), there was no difference in corn yield between oat–legume and oat-alone treatments. These patterns support the premise that legume green manure effects on corn yield were N-related. Red clover green manure had an N fertilizer replacement value for corn of 87–184 kg N ha−1; alfalfa supplied corn with the equivalent of 70–121 kg N ha−1. At a fossil energy cost for N fertilizer of 57 MJ kg−1 N, reducing synthetic N fertilizer applications to corn by 70–184 kg N ha−1 would represent a fossil fuel savings of 3990–10,488 MJ ha−1, equivalent to the energy content of 104–274 m3 of natural gas. These types of savings are likely to become increasingly important as fossil energy supplies become scarcer and fertilizer prices rise.


Corresponding author

*Corresponding author:


Hide All
1U.S. Department of Agriculture-Economic Research Service. 2011. Fertilizer Use and Price. USDA-Economic Research Service, Washington, DC. Available at Web site (verified May 20, 2011).
2Shapouri, H., Gallagher, P.W., Nefstead, W., Schwartz, R., Noe, R., and Conway, R. 2010. 2008 Energy Balance for the Corn–Ethanol Industry. Agricultural Economic Report 846. Office of the Chief Economist, US Department of Agriculture, Washington, DC.
3Oak Ridge National Laboratory. 2011. Biomass Energy Data Book. Appendix A—Conversions. Oak Ridge National Laboratory, US Department of Energy, Oak Ridge, TN. Available at Web site: (verified May 20, 2011).
4Huang, W., McBride, W., and Vasavada, U. 2009. Recent Volatility in U.S. Fertilizer Prices. Amber Waves, March 2009. USDA-Economic Research Service, Washington, DC. Available at Web site: (verified May 20, 2011).
5Cherr, C.M., Scholberg, J.M.S., and McSorley, R. 2006. Green manure approaches to crop production: A synthesis. Agronomy Journal 98:302319.
6Bruulsema, T.W. and Christie, B.R. 1987. Nitrogen contribution to succeeding corn from alfalfa and red clover. Agronomy Journal 79:96–100.
7Stute, J.K. and Posner, J.L. 1995. Legume cover crops as a nitrogen source for corn in an oat–corn rotation. Journal of Production Agriculture 8:385390.
8Snapp, S.S., Swinton, S.M., Labarta, R., Mutch, D., Black, J.R., Leep, R., Nyiraneza, J., and O'Neil, K. 2005. Evaluating cover crops for benefits, costs and performance within cropping system niches. Agronomy Journal 97:322332.
9Fox, R.H., Myers, R.J.K., and Vallis, I. 1990. The nitrogen mineralization rate of legume residues in soil as influenced by their polyphenol, lignin, and nitrogen contents. Plant and Soil 129:251259.
10Varco, J.J., Frye, W.W., Smith, M.S., and MacKown, C.T. 1993. Tillage effects on legume decomposition and transformation of legume and fertilizer nitrogen-15. Soil Science Society of America Journal 57:750756.
11Jarvis, S.C., Stockdale, E.A., Shepherd, M.A., and Powlson, D.S. 1996. Nitrogen mineralization in temperate agricultural soils: Processes and measurement. Advances in Agronomy 57:187235.
12Ruffo, M.L. and Bollero, G.A. 2003. Modeling rye and hairy vetch residue decomposition as a function of degree-days and decomposition-days. Agronomy Journal 95:900907.
13Paul, E.A. and Clark, F.E. 1996. Soil Microbiology and Biochemistry, 2nd ed.Academic Press, New York, NY.
14Seiter, S. and Horwath, W.R. 2004. Strategies for managing soil organic matter to supply plant nutrients. In Magdoff, F. and Weil, R.R. (eds). Soil Organic Matter in Sustainable Agriculture. CRC Press, Boca Raton, FL. p. 269293.
15Thorup-Kristensen, K., Magid, J., and Jensen, L.S. 2003. Catch crops and green manures as biological tools in nitrogen management in temperate zones. Advances in Agronomy 79:227302.
16ISU Mesonet. 2011. Daily Data. Iowa Environmental Mesonet, Iowa State University, Ames, IA. Available at Web site: (verified May 20, 2011).
17Bremner, J.M. 1996. Nitrogen-total. In Sparks, D.L.(ed.). Methods of Soil Analysis. Part 3. Chemical Methods. Soil Science Society of America, Madison, WI. p. 10851121.
18Hanway, J.J. 1963. Growth stages of corn (Zea mays L.). Agronomy Journal 55:487492.
19Blackmer, A.M. and Mallarino, A.P. 1996. Cornstalk Testing to Evaluate Nitrogen Management. Pm–1584. Iowa State University Extension, Ames, IA.
20SAS Institute, 2007. JMP 7.0.2. SAS Institute, Cary, NC.
21Higley, L.G. and Wintersteen, W. 1987. Using Degree Days in an Integrated Pest Management Program. Pm-1296. Iowa State University Extension, Ames, IA.
22Undersander, D., Smith, R.R., Kelling, K., Doll, J., Worf, G., Wedberg, J., Peters, J., Hoffman, P., and Shaver, R. 1990. Red Clover: Establishment, Management, and Utilization. Publication A3492. University of Wisconsin Extension, Madison, WI.
23Undersander, D., Martin, N., Cosgrove, D., Kelling, K., Schmitt, M., Wedberg, J., Becker, R., Grau, C., Doll, J., and Rice, M.E. 2004. Alfalfa Management Guide. American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Madison, WI.
24Tisdale, S.L., Nelson, W.L., Beaton, J.D., and Havlin, J.L. 1993. Soil Fertility and Fertilizers. 5th ed.MacMillan Publishing, New York, NY.
25Hammond, R.B. 1990. Influence of cover crops and tillage on seedcorn maggot (Diptera: Anthomyiidae) populations in soybeans. Environmental Entomology 19:510514.
26Thompson, B.K., Weiner, J., and Warwick, S.I. 1991. Size-dependent reproductive output in agricultural weeds. Canadian Journal of Botany 69:442446.
27Mutch, D.R., Martin, T.E., and Kosola, K.R. 2003. Red clover (Trifolium pratense) suppression of common ragweed (Ambrosia artemisiifolia) in winter wheat (Triticum aestivum). Weed Technology 17:181185.
28Morris, T.F., Blackmer, A.M., and El-Hout, N.M. 1993. Optimal rates of nitrogen fertilization for first-year corn after alfalfa. Journal of Production Agriculture 6:344350.
29Binford, G.D., Blackmer, A.M., and Meese, B.G. 1992. Optimal concentrations of nitrate in cornstalks at maturity. Agronomy Journal 84:881887.
30Cerrato, M.E. and Blackmer, A.M. 1990. Comparison of models describing corn yield response to nitrogen fertilizer. Agronomy Journal 82:138143.
31Pierce, F.J. and Rice, C.W. 1988. Crop rotation and its impact on efficiency of water and nitrogen use. In Hargrove, W.L. (ed.). Cropping Strategies for Efficient Use of Water and Nitrogen. Special Publication 51. American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Madison, WI. p. 2142.
32Hesterman, O.B., Griffin, T.S., Williams, P.T., Harris, G.H., and Christenson, D.R. 1992. Forage legume–small grain intercrops: Nitrogen production and response of subsequent corn. Journal of Production Agriculture 5:340348.
33Griffin, T., Liebman, M., and Jemison, J. Jr. 2000. Cover crops for sweet corn production in a short–season environment. Agronomy Journal 92:144151.
34U.S. Department of Agriculture-Economic Research Service. 2008. Agricultural Projections to 2017. USDA-Economic Research Service, Washington, DC. Available at Web site: (verified June 2, 2011).
35Nickel, S.E., Simmons, S.R., Sheaffer, C.C., and Radosevich, S.R. 1990. Addition series approach to assessing competition in a small grain-alfalfa companion crop community. Crop Science 30:11391141.
36Duffy, M. 2011. Estimated Costs of Crop Production in Iowa. Iowa State University Extension, Ames, IA. Available at Web site: (verified June 2, 2011).
37Chavas, J.-P., Posner, J.L., and Hedtcke, J.L. 2009. Organic and conventional production systems in the Wisconsin Integrated Cropping Systems Trial: II. Economic and analysis, 1993–2006. Agronomy Journal 101:288295.
38Cruse, M.J., Liebman, M., Raman, D.R., and Wiedenhoeft, M. 2010. Fossil energy use in conventional and low-external-input cropping systems. Agronomy Journal 102:934941.


Use of legume green manures as nitrogen sources for corn production

  • Matt Liebman (a1), Rhonda L. Graef (a2), Daniel Nettleton (a3) and Cynthia A. Cambardella (a4)


Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed