Sustainable Phosphorous Fertilizer Recommendations for Corn Production in the Northeast USA
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 Northeast 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 four 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.
To reevaluate corn responses to phosphorus fertilizer in the Northeast using
current crop production technology and soil test methods.
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.
To update phosphorus fertilizer recommendations for corn production in the Northeast.
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 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 four 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.
Impacts and potential contributions:
Amid the abundance of high P testing soils in the Northeast, the findings of the study are useful in Cooperative 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.
Reported April 2001