Phosphorus fertility recommendations for corn must be based on current soil test calibration research to ensure that recommendations are agronomically sound and sustainable. Experiments were conducted at 52 field sites in the Northeastern USA to study the relationship between soil test phosphorus and corn grain response to phosphorus fertilization. Corn responded to phosphorus fertilization at 15 experimental sites with increases in early vegetative growth and only at 4 of the 52 sites with increases in yield. Results indicate that corn producers with high and very high soil test phosphorus ratings can reduce P fertilizations without loss of corn yield.
1. To reevaluate corn responses to phosphorus fertilizer in the Northeast USA using
current crop production technology and soil test methods.
2. To determine the soil test phosphorus level that divides responsive soils from non-
responsive soils with respect to use of starter phosphorus fertilizer and broadcast phosphorus fertilizer.
3. To update phosphorus fertilizer recommendations for corn production in the Northeast USA.
4. To educate corn producers about sustainable soil phosphorus fertility management practices.
Corn responses to phosphorus (P) fertilization were determined at 52 experimental sites over a 12 state area (CT, DE, MA, MD, ME, NH, NJ, NY, PA, RI, VT, WV) during 1998 and 1999. Soil samples collected from each experimental site were analyzed for P using each of the five test extractants (Morgan, Modified Morgan, Mehlich-I, Mehlich-III, and Bray) that are in use in the region. The relationships between soil test P level and crop response to P fertilizer was examined using the Cate Nelson statistical procedure.
Corn responded to P fertilization at 15 experimental sites with increases in early growth and only at 4 of the 52 experimental sites with increases in yield. Our results show that P fertilization often accelerated early vegetative growth but there were generally little or no increases in corn yield. With so few sites exhibiting yield responses to P fertilization it was not possible to clearly determine the soil test P level that divides responsive soils from non-responsive soils.
The project findings were presented at the 1999 and 2000 meetings of the Northeast Coordinating Committee on Soil Testing (USDA-NEC67). Committee members (12 people) discussed the results in relation to current soil test P interpretations and recommendations.
September 14, 2000, NRCS Nutrient Management Training Meeting, 50 attendees, Trenton, NJ.
August 2, 2000, Field Crops Tour at Snyder Farm, 60 attendees, Pittstown, NJ.
January 31, 200, Nitrogen, Phosphorus and Environmental Concerns, 47 attendees, Moosup, CT, Agway Winter Crop Meeting.
March 3, 2000, Nitrogen and Phosphorus Management for the Long Term, 76 attendees, Plainfield, CT, meeting sponsored by CT DEP, NRCS, and Cooperative Extension.
March 7, 2000, Waste Management and Water Quality, 55 attendees, New England Turkey Growers Annual Meeting, Sturbridge, MA.
March 24, 2000, Nitrogen and phosphorus Management for the Long Term, 28 attendees, Hartford, CT, Meeting of the CT DEPâ€™s CAFO Advisory Committee.
September 6, 2000, Phosphorus Management, 7 people, Franklin, CT, very Alive Farmer Group of northeast Connecticut.
October 20, 2000, The P-Index, 32 attendees, Hartford, CT, Meeting of the CT DEPâ€™s CAFO Advisory Committee.
October 30, 2000, Phosphorus Management, 42 attendees, Torrington, CT, Litchfield County Committee.
Heckman, J.R., J.T. Sims, D. Beegle, F. Coale, S. Herbert. 2000. Nutrient Concentration and Uptake in Harvested Corn Grain. Agronomy Abstracts, p. 352.
Heckman, J.R., W.J. Bamka, and D. Kluchinski. 1998. Phosphorus Fertilization of Corn â€“ New Research to Update Recommendations. New Jersey Grain and Forage Journal. 5:16-17.
Impacts of Results/Outcomes
Amid the abundance of high P testing soils in the Northeast, the findings of the study are useful in Extension programming efforts to educate corn producers about sustainable P management practices. Our results indicate that corn producers with high and very high soil test P ratings can reduce P fertilization without loss of corn yield. As a result of this study corn producers are becoming aware that the frequently observed early growth responses to P fertilizer are often not followed by increases in corn yield.