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 Universityresearch organisationStillwater Agronomy Research Stationexperimental research station
- People
Site: Magruder Plots
- Type
- research station field
- Location
- StillwaterOklahomaUSA
- Geographic location
- 36.119728, -97.088711
- 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
Crop Years 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
Crop Years grown wheat - Factor
- Factor name
- Factor levels
- farmyard manure exposure
farmyard manure
no manure (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
Crop Years 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
Crop Years 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: wheatApplied every 4th year- liming exposure
with liming
Applied to crop: wheatLime 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 Nphosphate fertilizer exposure: With P
- NPK Treatment 5
- nitrogen fertilizer exposure: with Nphosphate fertilizer exposure: With Ppotassium fertilizer exposure: With K
- NPK+Lime Treatment 6
- nitrogen fertilizer exposure: with Nphosphate fertilizer exposure: With Ppotassium fertilizer exposure: With Kliming exposure: with liming
- Manure
- Measurements
Variable Material Units Frequency Scale Comment grain yield trait wheat nitrogen content wheat phosphorous content wheat soil pH Soil soil organic carbon Soil total soil nitrogen Soil plant available phosphorous Soil Mehlich III
Related publications
- Girma, K., Holtz, S.L., Arnall, D.B., Tubaña, B.S. and Raun, W.R. (2007), The Magruder Plots: Untangling the Puzzle. Agron. J., 99: 1191-1198. https://doi.org/10.2134/agronj2007.0008 [In English]
- Project website