Illinois
Fertilizer Conference Proceedings
January 27-29, 2003
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T.R. Peck1
The objective of this study is to evaluate soybean and corn crop yields in
relation to soil test levels of soil pH in an east central Illinois 40-acre
(16.2 hectare) field that has never received agricultural liming materials.
Composite 5-core soil samples for mapping soil pH levels are collected from
the center area of 5-rod grid areas (16 by 16 field grid pattern, 82.5 feet
grid area, 25 meter) and crop yields are measured with a combine yield monitor.
The 40-acre field, located in Champaign County near Thomasboro, is under University
Trust Management with recorded cultural management (unfarmed 1940 to 1982, crops
grown, yields and fertilizer analysis and rate). Soil types are dominantly Drummer
sicl and Harpster sicl. The field was cropped to soybeans in 2002 and will be
in corn in 2003. Soil samples were collected in October 2001.
Soil pH levels on the October 2001 samples show:
11 soil areas (each 0.156 acre, 82.5 feet square) with pH below 5.0;
96 soil areas with pH between 5.0 and 5.4;
55 soil areas with pH between 5.5 and 5.9;
27 soil areas with pH between 6.0 and 6.4;
20 soil areas with pH between 6.5 and 6.9;
45 soil areas with pH above 7.0.
Due to health problems, soybean yield for 2001 has not been evaluated.
1T.R. Peck is a professor
of soil chemistry extension, Department of Natural Resources and Environmental
Sciences, University of Illinois.
