Pedosphere 18(1): 60--68, 2008
ISSN 1002-0160/CN 32-1315/P
©2008 Soil Science Society of China
Published by Elsevier B.V. and Science Press
| Fertilizer-induced advances in corn growth stage and quantitative definitions of nitrogen deficiencies |
J. ZHANG 1,4, A. M. BLACKMER1, P. M. KYVERYGA1,2, B. W. VAN DE WOESTYNE1,3 and T. M. BLACKMER2 |
1 Department of Agronomy, Iowa State University, Ames, IA 50011 (USA). E-mail: jun.zhang@wright.edu;
2 Iowa Soybean Association, 4554 114th Street, Urbandale, IA 50325 (USA);
3 John Deere Ag Management Solutions, 140 114th Street, Urbandale, IA 50322 (USA);
4 Statistical Consulting Center, 130 MM, Wright State University, Dayton, OH 45435 (USA) |
| ABSTRACT |
| Evidence that nitrogen (N) fertilization tends to accelerate maturation as well as increase rates of growth has received little attention when diagnosing N deficiencies in corn (Zea mays L.). Such a tendency could be a potential source of errors when the diagnosis is solely based on comparing plants with different rates of growth. Whether N fertilization could accelerate rates of growth and maturation was tested in a field study with 12 paired plots representing relatively large variability in soil properties and landscape positions. The plots were located under conditions where preplant N fertilization reduced or avoided temporary N shortages for some plants but did not reduce for other plants early in the season. We measured corn heights to the youngest leaf collar, stages of growth and chlorophyll meter readings (CMRs). The added N advanced growth stages as well as increased corn heights and CMRs at any given time. Fertilization effects on corn heights, growth stages and ear weights were statistically significant (P < 0.05) despite substantial variability associated with landscape. Reductions in growth due to a temporary shortage of N within a growth stage might be partially offset by longer periods of growth within that stage to physiological maturity. Temporary shortages of N, therefore, may produce symptoms of N deficiency in situations where subsequent additions of N should not be expected to increase yields. Recognition of these two somewhat different effects (i.e., increase growth rates and advance growth stages) on corn growth could help to define N deficiency more precisely and to improve the accuracy of diagnosing N status in production agriculture. |
| Key Words: chlorophyll, corn, fertilizer, growth stage, nitrogen deficiency |
| Citation: Zhang, J., Blackmer, A. M., Kyveryga, P. M., De, W. and Blackmer, T. M. 2008. Fertilizer-induced advances in corn growth stage and quantitative definitions of nitrogen deficiencies. Pedosphere. 18(1): 60-68. |
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