University of Pretoria long-term maize and wheat trial

Local identifier
Hatfield long-term trial
Years operational
1939—
Objective
To determine the optimal rates of nitrogen, phosphorus, potassium and manure to apply to maize and wheat cropping systems.
Description
Originally the trial was split into maize-field pea and wheat-soybean rotations. The trial was irrigated and some treatments received manure. The objective was to determine the best fertiliser rates for maize and wheat in the region. In 1990 the manure applications stopped, and whereas half the summer crop treatments received either only rainfall or rainfall and irrigation before, following 1990 only supplemental irrigation was applied. In 1999 the rotations were stopped, so currently half the trial is maize-fallow, and half the trial is wheat-fallow.
Data Access Statement
Available to collaborators only
Data Access Notes
Data can be made available on request.
Data license
Other
Data policy
Yes (not online)
Organization
University of Pretoria
Custodian
People
Dr Michael van der Laan
data manager
Agricultural Research Council and University of Pretoria
Department of Plant and Soil Sciences
Dr Diana Marais
experiment manager
University of Pretoria
Department of Plant and Soil Sciences

Site: Future Africa

Local code
Hatfield trial
Location
Hatfield, Pretoria
Gauteng
South Africa
Geographic location
-25.74912, 28.259227
© OpenStreetMap contributors
Elevation
1372 Metres
Slope
(North facing)
Visits permitted?
Yes
Visiting arrangements
Please arrange with contact people for the LTE.
History
Donated to the University of Pretoria for agricultural research. Current trial started in 1939. Previously known as the University of Pretoria Hatfield Experimental Farm, now known as the Future Africa.
Management
Managed by a research farm manager.
Soil type
acrisol
Soil description
The soil was classified as a sandy loam of the Hutton form and belong to the Suurberkom Family (Soil Classification and Working Group 1991) [Acrisol according to Food and Agriculture Organization of the United Nations World Reference Base (WRB), WRB (2014)].
Climatic type
Cbw
Climate description
The long-term average annual rainfall for Pretoria is 670 mm, which is mostly received in summer, with about 80% falling between October and March. The average annual potential evapotranspiration (PET) is approximately 2 000 mm, which gives the site an aridity index of 0.3–0.35.

Design period: Original trial and two modifications (1939—)

Design Type
Randomized complete block design
Description
Maize-field pea rotation, and wheat-soybean rotation from 1939-1999. Then switched to maize-fallow (half the area of the trial) and wheat-fallow design (half the area of the trial) from 2000 until present. Yield measurements were only done for maize and wheat.
Design description
The treatments were made in combinations of N/P/K, and manure (M), which resulted in a total of 32 treatments with four replications leading to 128 plots
Number of plots
128
Number of subplots
64
Number of replicates
4
Number of harvests per year
2
Crops
CropYears grown
maize
wheat
peas
soybeans
fallow
Crop Rotations
Maize  1939—1999
  • 1
    maize
  • 2
    peas
  • 3
    wheat
  • 4
    soybeans
maize-fallow  2000—
  • 1
    maize
  • 2
    fallow
wheat-fallow  2000—
  • 1
    maize
  • 2
    fallow
Factors
Factor name
Factor levels
Macro-nutrients
Different combinations of nitrogen, phosphorus and potassium
Manure
Manure was applied to half of the plots receiving different N/P/K combinations. Manure application was discontinued in 1990, after which only inorganic fertiliser was applied.
Irrigation
From 1939 - 1990, half the plots were purely rain-fed and the others irrigated. From 1990, all plots received supplementary irrigation when no rain was received over a period of two weeks.
Measurement
VariableMaterialUnitsFrequencyScaleComment
Maize and wheat grain yieldNot specifiedkg/haSeasonallyOnly yield was consistently measured. There has been research over the years that has measured more variables for one or two seasons. Examples are soil water content at different depths and weed populations.

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