Summary
Both N and P are needed by plants in large amounts, but when soils are too rich in these nutrients, they are environmental hazards. And although N and P behave differently in soils, most sound management practices for one are also sound for the other. Using soil tests (and for N on corn the end-of-season lower stalk nitrate test) and modern nutrient management planning that credits all sources, such as manures and decomposing sods, can help better manage these nutrients. Reduced tillage, cover crops, and rotation with sod crops decrease runoff and erosion and help in many other ways, including better N and P management.
Sources
Balkcom, K.S., A.M. Blackmer, D.J. Hansen, T.F. Morris, and A.P. Mallarino. 2003. Testing soils and cornstalks to evaluate nitrogen management on the watershed scale. Journal of Environmental Quality 32: 1015–1024.
Brady, N.C., and R.R. Weil. 2008. The Nature and Properties of Soils, 14th ed. Upper Saddle River, NJ: Prentice Hall.
Cassman, K.G., A. Dobermann, and D.T. Walters. 2002. Agroecosystems, nitrogen-use efficiency, and nitrogen management. Ambio 31: 132–140.
Jokela, B., F. Magdoff, R. Bartlett, S. Bosworth, and D. Ross. 1998. Nutrient Recommendations for Field Crops in Vermont. Burlington: University of Vermont, Extension Service.
Kay, B.D., A.A. Mahboubi, E.G. Beauchamps, and R.S. Dharmakeerthi. 2006. Integrating soil and weather data to describe variability in plant available nitrogen. Soil Science Society of America Journal 70: 1210–1221.
Laboski, C.A.M., J.E. Sawyer, D.T. Walters, L.G. Bundy, R.G. Hoeft, G.W. Randall, and T.W. Andraski. 2008. Evaluation of the Illinois Soil Nitrogen Test in the North Central region of the United States. Agronomy Journal 100: 1070–1076.
Magdoff, F.R. 1991. Understanding the Magdoff pre-sidedress nitrate soil test for corn. Journal of Production Agriculture 4: 297–305.
Melkonian, J., H.M. van Es, A.T. DeGaetano, J.M. Sogbedji, and L. Joseph. 2007. Application of dynamic simulation modeling for nitrogen management in maize. In Managing Crop Nutrition for Weather, ed. T. Bruulsema, pp. 14–22. Norcross, GA: International Plant Nutrition Institute Publication.
Mitsch, W.J., J.W. Day, J.W. Gilliam, P.M. Groffman, D.L. Hey, G.W. Randall, and N. Wang. 2001. Reducing nitrogen loading to the Gulf of Mexico from the Mississippi River basin: Strategies to counter a persistent ecological problem. BioScience 51: 373–388.
National Research Council. 1988. Nutrient Requirements of Dairy Cattle, 6th rev. ed. Washington, DC: National Academy Press.
Olness, A.E., D. Lopez, J. Cordes, C. Sweeney, and W.B. Voorhees. 1998. Predicting nitrogen fertilizer needs using soil and climatic data. In Procedures of the 11th World Fertilizer Congress, Gent, Belgium, Sept. 7–13, 1997, ed. A. Vermoesen, pp. 356–364. Gent, Belgium: International Centre of Fertilizers.
Sawyer, J., E. Nafziger, G. Randall, L. Bundy, G. Rehm, and B. Joern. 2006. Concepts and Rationale for Regional Nitrogen Guidelines for Corn. Iowa State University Extension Publication PM2015, 27 pp.
Sharpley, A.N. 1996. Myths about P. Proceedings from the Animal Agriculture and the Environment North American Conference, Dec. 11–13, Rochester, NY. Ithaca, NY: Northeast Region Agricultural Engineering Service.
van Alphen, B.J., and J.J. Stoorvogel. 2000. A methodology for precision nitrogen fertilization in high-input farming systems. Precision Agriculture 2: 319–332.
Vigil, M.F., and D.E. Kissel. 1991. Equations for estimating the amount of nitrogen mineralized from crop residues. Soil Science Society of America Journal 55: 757–761.
Wortmann, C., M. Helmers, A. Mallarino, C. Barden, D. Devlin, G. Pierzynski, J. Lory, R. Massey, J. Holz, and C. Shapiro. 2005. Agricultural Phosphorus Management and Water Quality Protection in the Midwest. Lincoln: University of Nebraska.
Table of Contents
- About the Authors
- Preface
- Introduction
- Healthy Soils
- Organic Matter: What It Is and Why It's So Important
- Amount of Organic Matter in Soils
- The Living Soil
- Soil Particles, Water, and Air
- Soil Degradation: Erosion, Compaction, and Contamination
- Nutrient Cycles and Flows
- Soil Health, Plant Health, and Pests
- Managing for High Quality Soils: Organic Matter, Soil Physical Condition, Nutrient Availability
- Cover Crops
- Crop Rotations
- Animal Manures for Increasing Organic Matter and Supplying Nutrients
- Making and Using Composts
- Reducing Erosion and Runoff
- Preventing and Lessening Compaction
- Reducing Tillage
- Managing Water: Irrigation and Drainage
- Nutrient Management: An Introduction
- Management of Nitrogen and Phosphorus
- Other Fertility Issues: Nutrients, CEC, Acidity, and Alkalinity
- Getting the Most From Routine Soil Tests
- Taking Soil Samples
- Accuracy of Recommendations Based on Soil Tests
- Sources of Confusion About Soil Tests
- Soil Testing for Nitrogen
- Soil Testing for P
- Testing Soils for Organic Matter
- Interpreting Soil Test Results
- Adjusting a Soil Test Recommendation
- Making Adjustments to Fertilizer Application Rates
- Managing Field Nutrient Variability
- The Basic Cation Saturation Ratio System
- Summary and Sources
- How Good Are Your Soils? Field and Laboratory Evaluation of Soil Health
- Putting It All Together
- Glossary
- Resources