Author
HECKMAN, J - RUTGERS | |
JOKELA, W - UNIV OF VERMONT | |
MORRIS, T - UNIV OF CONNECTICUT | |
BEEGLE, D - PENN STATE UNIV | |
SIMS, T - UNIV OF DELAWARE | |
COALE, F - UNIV OF MARYLAND | |
HERBERT, S - UNIV OF MASSACHUSETTS | |
Griffin, Timothy | |
HOSKINS, B - UNIV OF MAINE | |
JEMISON, J - UNIV OF MAINE |
Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 8/10/2005 Publication Date: 2/7/2006 Citation: Heckman, J.R., Jokela, W., Morris, T., Beegle, D.B., Sims, T., Coale, F.J., Herbert, S., Griffin, T.S., Hoskins, B., Jemison, J. 2006. Soil test calibration for predicting corn response to phosphorus in the northeast usa. Agronomy Journal. 98:280-288 Interpretive Summary: The soil testing and recommendation systems for phosphorus (P) needs to be reexamined because of recent changes in soil testing methodology in the laboratory and corn (Zea mays L.) production technology in the field. Standard soil tests were performed on samples from soil test calibration studies conducted during 1998 to 1999 at 51 experimental sites chosen to represent a range of soils in twelve Northeastern states. Production practices followed local state extension recommendations at each site and included three P fertilizer treatments: none, 15 kg P ha-1 banded, or 60 kg P ha-1 broadcast. Combined analysis across all 51 sites showed that plant height at 35 days after planting, timing of silk emergence, grain yield, and grain dry down were enhanced by the broadcast P treatment. There were yield increases due to the banded P treatment at only 4 sites and to the broadcast P treatment at 9 sites. Statistical analysis of relative yield in relation to soil test P failed to identify soil test P critical levels for any of the soil test methods. Results showed that 17 to 47% of those sites testing below the critical level exhibited a yield increase to broadcast P. Some of the yield responsive sites had soil test P above currently used critical levels. This study shows that the current critical levels frequently permit both types of errors in soil test prediction; indicating a need for P fertilization when it may not be needed and not indicating a need for P fertilization when it may be needed. The second type of error is usually avoided by recommendations for crop removal rates of P. Technical Abstract: The consensus of soil fertility specialists working in the Northeast USA was that soil testing and recommendation systems for P needed to be reexamined because of recent changes in soil testing methodology in the laboratory and corn (Zea mays L.) production technology in the field. Standard soil tests were performed on samples from soil test calibration studies conducted during 1998 to 1999 at 51 experimental sites chosen to represent a range of soils in twelve Northeastern states. Production practices followed local state extension recommendations at each site and included three P fertilizer treatments: none, 15 kg P ha-1 banded, or 60 kg P ha-1 broadcast. Combined analysis of variance over sites showed that plant height at 35 d after planting, silk emergence, grain yield, and grain dry down were enhanced by the broadcast P treatment. There were yield increases (P<0.10) to the band treatment at only 4 sites and to the broadcast treatment at 9 sites. Cate-Nelson statistical analysis of relative yield in relation to soil test P failed to identify soil test P critical levels for any of the soil test methods. Results showed that 17 to 47% of those sites testing below the critical level exhibited a yield increase (P<0.10) to broadcast P. Some of the yield responsive sites had soil test P above currently used critical levels. This study shows that the current critical levels frequently permit both types of errors in soil test prediction; indicating a need for P fertilization when it may not be needed and not indicating a need for P fertilization when it may be needed. The second type of error is usually avoided by recommendations for crop removal rates of P. |