Magruder Plots

This experiment has been added by the GLTEN Curators using existing published sources.
Objective
The Magruder plots were initially established to evaluate wheat production on native prairie soils without fertilization. The experiment has undergone several modifications since to evaluate fertilization on soil fertility.
Description
Initially only one plot was established to evaluate native wheat production without the application of organic or inorganic fertilizers from 1893 to 1898. From 1899 to 1929, half of the experimental area was fertilized with barnyard manure while the other half received no fertilization. In 1930, ten fertilization treatments were established on these plots. In 1947, to make way for new University buildings, the surface soil (40.6 cm) from six plots were moved 1.6 km west from its original location to the Stillwater Agronomy Research Station. The subsoil at the new location was noted to be very similar to that of the original site.
Data Access Statement
Freely available online
Data Access Notes
Data is available for download as an Excel file, but no licence, DOI or citation recommendation is provided.
Data license
Don't know
Data URL
https://www.nue.okstate.edu/Long_Term_Experiments/Magruder_Plots_Yield_Summary_files/EMAG_18.xlsx
Data policy
Don't know
Organizations
Oklahoma State University
research organisation
Stillwater Agronomy Research Station
experimental research station
People

Site: Magruder Plots

Type
research station field
Location
Stillwater
Oklahoma
United States of America
Geographic location
36.119728, -97.088711
© OpenStreetMap contributors
Elevation
272 Metres
Visits permitted?
No
Soil description
Kirkland silt loam (fine, mixed, thermic Udertic Paleustolls)

Design period: Period 1 (1892—1898)

Design description
Single plot growing wheat only and no fertilizers inputs.
Number of plots
1
Number of harvests per year
1
Crop
CropYears grown
wheat

Design period: Period 2 (1898—1929)

Design description
The experiment was split into two plots, one half fertilized with farmyard manure and the other continuing to receive no inputs.
Number of plots
2
Number of harvests per year
1
Crop
CropYears grown
wheat
Factor
Factor name
Factor levels
farmyard manure exposure
farmyard manure
No maure  (0 )

Design period: Period 3 (1930—1947)

Design description
In 1930 the experiment was divided into 10 plots to test 10 different combinations of fertility treatments.
Number of plots
10
Number of harvests per year
1
Crop
CropYears grown
wheat

Design period: Period 4 - New site (1947—)

Description
The experiment was established at a new site using transplanted soil from 6 of the original 10 treatment plots.
Design description
Plots measure 17.5 x 30.5m
Number of plots
6
Number of harvests per year
1
Crop
CropYears grown
wheat
Factors
Factor name
Factor levels
nitrogen fertilizer exposure
With N  (67.3 kgN/ha)
Applied to crop: wheat
phosphate fertilizer exposure
With P  (33.6 kgP/ha)
Applied to crop: wheat
potassium fertilizer exposure
With K  (33.6 kgK/ha)
Applied to crop: wheat
farmyard manure exposure
With manure
Applied to crop: wheat
Applied every 4th year
liming exposure
With liming
Applied to crop: wheat
Lime applied when soil pH < 5.5
Factor combinations
Manure
Treatment 1
farmyard manure exposure: With manure
Control
Treatment 2. No inputs
P
Treatment 3
phosphate fertilizer exposure: With P
NP
Treatment 4
nitrogen fertilizer exposure: With N
phosphate fertilizer exposure: With P
NPK
Treatment 5
nitrogen fertilizer exposure: With N
phosphate fertilizer exposure: With P
potassium fertilizer exposure: With K
NPK+Lime
Treatment 6
nitrogen fertilizer exposure: With N
phosphate fertilizer exposure: With P
potassium fertilizer exposure: With K
liming exposure: With liming
Measurements
VariableMaterialUnitsFrequencyScaleComment
grain yield traitwheat
nitrogen contentwheat
phosphorous contentwheat
soil pHSoil
soil organic carbonSoil
total soil nitrogenSoil
plant available phosphorousSoilMehlich III

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