Abstract:
The exact origin of the Morrow plots on the campus of the University
of Illinois is obscure, but they are reputed to be the oldest
continuous agronomic research study in the USA. Some evidence
indicates that the plots were established in 1876, however the first
yield records begin in 1888 when the Illinois Agricultural Experiment
Station began. Included with the records are notes stating that the
... plots were cropped during the previous 14 years in continuous corn, in
a corn-oats rotation and a corn-oats-clover hay rotation. Not too long
before 1876 the site would have been in native tall grass (big
bluestem, Andropogon gerardi) prairie. In early field research studies
it was common to not record yields until the studt reached equilibrium
with the treatments. The plots are located in Champaign County,
Illinois on the Bloomington ridged plain. This is a Wisonsinan-aged
till plain that is covered with about one meter of Peoria loess. For
sometime during and after the retreat of the last Wisconsinan glacial
ice from Illinois some 12,000 years ago, the climate was cooler and
wetter than at present. A rather warm, dry period 4,000-6,000 years
ago led to an expension of grassland in the area. Since that time, the
climate seems to have remained similar to that today. The elevation of
the plots is about 225 m above sea level.
The soil of the Morrow plots is Flanagan silt loam, a fine,
montmorillonitic, mesic Aquic Arguidoll (USDA). Flanagan silt loam is
a nearly level, dark coloured, somewhat poorly drained soil. Developed
in 100-150cm of loess over loamy, firm Wisconsinan-age calcareous
till. The A horizon is about 46 cm thick. Before the 1904 season,
underground tile lines were installed in the plots to provide
supplemental drainage.
the experiment consists of three rotations: continuous corn,
corn-soybean, and corn-oat-clover hay. All rotations have the
following general treatments: 1) no amendments, 2) lime,
lime-nitrogen-phosphorus-potassium (LNPK), 3) Manure-lime-phosphorus
(MLP). Rates have varied over the years.
The measurements made, methodology, and frequency are listed below:
a) Vegetation measurements made and frequency
Yield: Yearly
b) Soil sampling
Details of soil sampling method: There has not been a systematic
soil sampling scheme. Samples are taken by a variety of methods as
appropriate and when necessary. Soil fertility samples are usually
taken with a 3 cm tube from near the plot centre. Soil is separated
into layers.
Details of measuring depths and soil layers: No set methods.
Samples have been taken over the years in a variety of ways. The
deepest sampling exceeds 1 metre. Most samples are for the upper 25cm.
c) Soil measurements made and frequency
Total carbon: About every 5 years since 1904
Method of measuring total carbon: The analytical method is a
modification of the method of Schollenberger which involves an oxidising
solution of concentrated sulphuric acid/potassium dichromate at 175 deg. C
for 90 seconds (see Schollenberger, C.J. Determination of soil organic
matter. Soil Sci. 59: 53-56).
Carbon measurements in other organic matter fractions: Once in 1956
Method of measuring carbon in other organic matter fractions: See
Stevenson, F.J. (1956) Effect of some long-time rotations on the amino
acid composition of the soil. Soil Sci. Soc. Amer. Proc. 20: 204-208.
Total nitrogen: 10 yearly - sporadic
Method of measuring total nitrogen: Kjeldahl method - Methods of
Analysis of the Association of Official Agicultural Chemists, ed. 5,
Washington D.C., 1940.
Soil bulk density or weight: Sporadic on a limited number of plots.
Method of measuring soil bulk density or weight: Clod method on 2
plots
Other nutrients: Ca, Mg, K, Na - Extractable in weak acid
Other measurements: Hg has been measured on plots (Jones &
Hinesly, 1972 - see reference list). Aggregation measured on selected
subplots (Darmody & Norton, 1994; Stauffer et al., 1940 - see
reference list).
d) Details of the meteorological station
Nearest meteorological station to the site: Urbana (#118740) which
is 3.2 km from the site at coordinates 88deg.14min.20sec. West,
40deg.05min.14sec. North Meteorological data is available from both a
manual and an automatic station.
e) Meteorological data available and frequency
Rainfall: Daily
Air temperature: Daily
Soil temperature: Daily at 5 and 15 cm depth
Wind speed: Hourly
Net Radiation: Daily
Sun hours: Daily
Relative humidity: Daily
Potential evapotranspiration: Daily measured/calculated by open pan
f) Isotope measurements available and frequency
Total soil carbon 14 measurements: Once to compare 1988 with 1944
Details of isotope measurements: Details in Hsieh, Y.-P. (1992) Pool
size and mean age of stable soil organic carbon in cropland. Soil Sci.
Soc. Am.
J. 56: 460-464.
This information was compiled for the GCTE-SOMNET Database, Pete
Smith, Pete Falloon, David Powlson, and Jo Smith. Soil Science
Department, IACR-Rothamsted, UK.