Broadbalk

Local identifier
R/BK/1
Years operational
1843— (Establishment period end: 1951)
Objective
The aim of the experiment was to test the effect of different organic manures and inorganic fertilizers on the yield of winter wheat.
Description
The Broadbalk experiment is one of the oldest continuous agronomic experiments in the world. Started by Lawes and Gilbert in the autumn of 1843, winter wheat has been sown and harvested on all or part of the field every year since then. The original aim of the experiment was to test the effects of various combinations of inorganic fertilizers (supplying the elements N, P, K, Na and Mg) and different organic manures on the yield of winter wheat; a control strip has received no fertilizer or organic manures since 1843. For the first few years these treatments varied a little, but in 1852 a scheme was established that has continued, with some modifications, until today.
Farm operation data?
Sample archive?
Samples available?
 
Data Access Statement
No data statement
Data license
CC BY
Data policy
Yes (not online)
Organization
Rothamsted Research
research organisation
People
Dr Andy Macdonald
Dr Sarah Perryman
Dr Margaret Glendining

Site: Broadbalk

Type
research station field
Location
Harpenden
Hertfordshire
United Kingdom
Geographic location
51.80946, -0.37301
© OpenStreetMap contributors
Elevation
130 Metres
Visits permitted?
Yes
Visiting arrangements
Contact Andy Macdonald
History
The first experimental crop was harvested in 1844 after a rotation of turnips (dunged) 1839, barley 1840, peas 1841, wheat 1842 and oats 1843. The last four crops being entirely unmanured. The field was therefore considered to be exhausted according to contemporary practice.
Management
The site is managed using conventional tillage and pesticide applications are applied as necessary, except for herbicide and fungicide exclusion plots. The plough layer (0-23 m) is limed when necessary to maintain a minimum soil pH of 7.0 – 7.5.
Soil type
luvisol
Soil description
The soil is classified as a Chromic luvisol. The soil texture is described as clay loam to silty clay loam over clay-with flints. The soils contain a large number of flints and are slightly calcareous. Below about 2m depth the soil becomes chalk. The experiment is under-drained and the site is free draining. There is considerable variation in soil texture across the site, with clay contents ranging from 19 – 39%
Soil properties
VariableDepthValue (range)UnitsRef yearEstimated?Baseline?
sand content Metres25 Percent
silt content Metres50 Percent
clay content Metres25 Percent

Design period: Early period (1852—1925)

Design Type
Demonstration strip design
Design description
The experiment was divided into different Strips or 'Plots' (2 - 20) receiving the different fertilizer and manure treatments each year. Most treatment strips were established by 1852, except for strip 2A, which began in 1885, and strip 20, which began in 1906. Plot 19 was originally a half plot, and became its current size in 1904. Between 1894 and 1925 many plots were harvested in two halves, Top (T) and Bottom (B), equivalent to the Western and Eastern parts of the experiment.
Number of harvests per year
1
Crop
CropYears grown
winter wheat
Factor
nitrogen fertilizer exposure
Plot application: Whole plot
N1  (48 kgN/ha)
1852—1925
Chemical form: ammonium sulfate
N1*  (48 kgN/ha)
1852—1983
Chemical form: sodium nitrate
N1.5  (72 kgN/ha)
1852—1852
Application frequency: 1878
Chemical form: ammonium sulfate
N2  (96 kgN/ha)
1852—1925
Chemical form: ammonium sulfate
N2*  (96 kgN/ha)
1855—1884
Chemical form: sodium nitrate
N3  (144 kgN/ha)
1852—1925
Chemical form: ammonium sulfate
N4  (192 kgN/ha)
1852—1925
Chemical form: ammonium sulfate
Factor combinations
FYM  1885—1925
nitrogen fertilizer exposure: N2  (35 t/ha)
Supplying approximately 225 kgN/ha
Applied to crop: winter wheat
FYM  1843—1925
nitrogen fertilizer exposure: N2  (35 t/ha)
Supplying approximately 225 kgN/ha
Nil  1843—1925
nitrogen fertilizer exposure: N3  (0 )
PKNaMg  1843—
nitrogen fertilizer exposure: N1.5  (35 kgP/ha)
As superphosphate
nitrogen fertilizer exposure: N1*  (90 kgK/ha)
As potassium sulphate
nitrogen fertilizer exposure: -
N1 PKNaMg  1843—1925
nitrogen fertilizer exposure: N1  (48 kgN/ha)

Design period: Middle period (1926—1927)

Crop
CropYears grown
winter wheat

Design period: Current period

Description
Two major modifications were made from 1968: i) The division of Sections I to V to create 10 new Sections (0 - 9), so the yield of wheat grown continuously could be compared with that of wheat grown in rotation after a two-year break. ii) The introduction of modern, short-strawed cultivars, which lead to an increase in grain yields and a decrease in straw yields. The old cultivar Squarehead's Master was grown on parts of some plots between 1987 and 1990, enabling a comparison to be made with modern cultivars After the 1968 changes, Sections 0, 1, 8 and 9 continued to grow winter wheat only, whilst Sections 2, 4, 7 and Sections 3, 5, 6 went into two different 3-course rotations (see 1968 cropping details link). In 1978, Section 6 reverted to continuous wheat and the other five Sections went into a five year rotation. Pesticides are applied where necessary, except on Section 6, which does not receive spring or summer fungicides. Herbicides have been used as required since 1964 on all of the experiment, except for Section 8 (old Section VA), which has never received herbicides. On Section 0 the straw on each plot has been chopped after harvest and incorporated in the soil since autumn 1986; on all other Sections the straw is baled and removed. In 1993 Section 9 was re-drained so that water leaching through the soil could again be collected and analysed. Lime has been applied as required since the 1950s to maintain soil pH at a level at which crop yield is not limited. From 2001 P has not been applied to some plots until levels of plant available P decrease to more appropriate agronomic levels. This is reviewed each year.
Number of harvests per year
1
Crops
CropYears grown
winter wheat 1968—
oats 1996—
beans 1968—1978
potatoes 1968—1996
beans 2018—
fallow
maize 1997—2017
Crop Rotations
continuous wheat  1968—
  • 1
    winter wheat
F-W-W  1968—1981
  • 1
    fallow
  • 2
    winter wheat
  • 3
    winter wheat
P-Be-W  1968—1979
  • 1
    potatoes
  • 2
    beans
  • 3
    winter wheat
F-P-W-W-W  1982—1999
  • 1
    fallow
  • 2
    potatoes
  • 3
    winter wheat
  • 4
    winter wheat
  • 5
    winter wheat
O-M-W-W-W  1996—2017
  • 1
    oats
  • 2
    maize
  • 3
    winter wheat
  • 4
    winter wheat
  • 5
    winter wheat
W-W-O-W-Be  2018—
  • 1
    winter wheat
  • 2
    winter wheat
  • 3
    oats
  • 4
    winter wheat
  • 5
    beans
Factors
nitrogen fertilizer exposure
N was applied as calcium ammonium nitrate (Nitro-chalk) between 1968 and 1985. Between 1968-1996 N was applied at the same rate to beans and potatoes. Between 1996-2017 oats did not receive N. Since 2018 Oats receive N at half the normal rate. Between 1997-2017 split N treatments were applied twice to the seedbed and post-emergence.
Plot application: Whole plot
Effect: Direct
N1  (48 kgN/ha)
1968—
Application frequency: annually in mid-April
N2  (96 kgN/ha)
1968—
Chemical form: ammonium nitrate
N3  (144 kgN/ha)
1968—
Chemical form: ammonium nitrate
N4  (192 kgN/ha)
1986—
Applied to crop: winter wheat
Chemical form: ammonium nitrate
N5  (240 kgN/ha)
1985—
Application frequency: annually in spring
Chemical form: ammonium nitrate
N6  (288 kgN/ha)
1985—
Application frequency: annually in spring
Chemical form: ammonium nitrate
N1+1+1  (144 kgN/ha)
2001—
Application frequency: mid-March, mid-April, Mid-May
Chemical form: ammonium nitrate
N2+1 for maize
N1+2+1  (192 kgN/ha)
2001—
Application frequency: mid-March, mid-April, Mid-May
Chemical form: ammonium nitrate
N2+2 for maize
N1+3+1  (240 kgN/ha)
2001—
Applied to crop: winter wheat
Application frequency: mid-March, mid-April, Mid-May
Chemical form: ammonium nitrate
N2+3 for maize
N1+4+1  (288 kgN/ha)
2001—
Applied to crop: winter wheat
Application frequency: mid-March, mid-April, Mid-May
Chemical form: ammonium nitrate
N2+4 for maize
potassium fertilizer exposure
Plot application: Whole plot
K  (90 kgK/ha)
1968—
Chemical form: potassium sulphate
K2  (180 kgK/ha)
2001—2005
Chemical form: potassium sulphate
K*  (90 kgK/ha)
2001—
Chemical form: potassium chloride
phosphate fertilizer exposure
Plot application: Whole plot
P  (35 kgP/ha)
1968—2001
Chemical form: calcium bis(dihydrogenphosphate)
sodium nutrient exposure
Plot application: Whole plot
Na1  (16 kgNa/ha)
1968—1973
Chemical form: sodium sulphate
Na2  (55 kgNa/ha)
1968—2000
Chemical form: sodium sulphate
57 kgNa/ha until 1973
magnesium nutrient exposure
Plot application: Whole plot
Mg  (12 kgMg/ha)
1968—
Chemical form: magnesium sulphate
11kgMg until 1973. 35 kgMg every 3rd year 1974-2000.
Mg2  (24 kgMg/ha)
2001—2005
Chemical form: magnesium sulphate
Plus 60 kg Mg in autumn 2000 only
Mg*  (30 kgMg/ha)
1968—2000
Chemical form: magnesium sulphate
31kgMg as magnesium sulphate until 1973
farmyard manure exposure
Plot application: Whole plot
FYM  (35 t/ha)
1968—
Application frequency: annually in spring
Derived from cattle
Residual FYM
2001—
Plots previously receiving FYM
castor meal exposure
Plot application: Whole plot
C  (96 kgN/ha)
1968—1988
Residual C
Plots previously receiving
Factor combinations
FYM N2 PK  1968—1984
nitrogen fertilizer exposure: N2
farmyard manure exposure: FYM
phosphate fertilizer exposure: P
potassium fertilizer exposure: K
FYM N4 PK  1985—2000
farmyard manure exposure: FYM
nitrogen fertilizer exposure: N4
phosphate fertilizer exposure: P
potassium fertilizer exposure: K
(FYM) N4  2001—
farmyard manure exposure: Residual FYM
nitrogen fertilizer exposure: N4
FYM N2  1968—2004
farmyard manure exposure: FYM
nitrogen fertilizer exposure: N2
FYM N3  2005—
farmyard manure exposure: FYM
nitrogen fertilizer exposure: N3
FYM  1968—
farmyard manure exposure: FYM
Nil  1968—
(P)K(Na)Mg  1968—1973
phosphate fertilizer exposure: P
P not applied since 2000 due to high soil levels, reviewed annually.
potassium fertilizer exposure: K
sodium nutrient exposure: Na1
Applied until 1973
magnesium nutrient exposure: Mg
N1 (P)K(Na)Mg  1968—
nitrogen fertilizer exposure: N1
phosphate fertilizer exposure: P
P not applied since 2000 due to high soil levels, reviewed annually.
potassium fertilizer exposure: K
sodium nutrient exposure: -
Applied until 1973
magnesium nutrient exposure: Mg
N2 (P)K(Na)Mg  1968—
nitrogen fertilizer exposure: N2
phosphate fertilizer exposure: P
P not applied since 2000 due to high soil levels, reviewed annually.
potassium fertilizer exposure: K
sodium nutrient exposure: Na1
Applied until 1973
magnesium nutrient exposure: Mg
N3 (P)K(Na)Mg  1968—
nitrogen fertilizer exposure: N3
phosphate fertilizer exposure: P
P not applied since 2000 due to high soil levels, reviewed annually.
potassium fertilizer exposure: K
sodium nutrient exposure: Na1
Applied until 1973
magnesium nutrient exposure: Mg
N4 (P)K(Na)Mg  1968—
nitrogen fertilizer exposure: N4
phosphate fertilizer exposure: P
P not applied since 2000 due to high soil levels, reviewed annually.
potassium fertilizer exposure: K
sodium nutrient exposure: Na1
Applied until 1973
magnesium nutrient exposure: Mg
N2  1968—2000
nitrogen fertilizer exposure: N2
N4  2001—
nitrogen fertilizer exposure: N4
N2 P  1968—2000
nitrogen fertilizer exposure: N2
phosphate fertilizer exposure: P
N4 PMg  2001—
nitrogen fertilizer exposure: N4
phosphate fertilizer exposure: P
magnesium nutrient exposure: Mg
N2 PNa  1968—2000
nitrogen fertilizer exposure: N2
phosphate fertilizer exposure: P
sodium nutrient exposure: Na2
N1+3+1 (P)K2Mg2  2001—2005
nitrogen fertilizer exposure: N1+3+1
potassium fertilizer exposure: K2
magnesium nutrient exposure: Mg2
N1+3+1 (P)KMg  2006—
nitrogen fertilizer exposure: N1+3+1
potassium fertilizer exposure: K
magnesium nutrient exposure: Mg
N2 PK  1968—2000
nitrogen fertilizer exposure: N2
phosphate fertilizer exposure: P
potassium fertilizer exposure: K
N4 PK  2001—
nitrogen fertilizer exposure: N4
phosphate fertilizer exposure: P
potassium fertilizer exposure: K
N2 PKMg*  1968—2000
nitrogen fertilizer exposure: N2
phosphate fertilizer exposure: P
potassium fertilizer exposure: K
magnesium nutrient exposure: Mg*
N4 PK*  2001—
nitrogen fertilizer exposure: N4
phosphate fertilizer exposure: P
potassium fertilizer exposure: K*
N5 (P)KMg  1985—
nitrogen fertilizer exposure: N5
phosphate fertilizer exposure: P
Applied until 200, reviewed annually since
potassium fertilizer exposure: K
magnesium nutrient exposure: Mg
N6 (P)KMg  1985—
nitrogen fertilizer exposure: N6
phosphate fertilizer exposure: P
Applied until 2000, reviewed annually since
potassium fertilizer exposure: K
magnesium nutrient exposure: Mg
N2 1/2[PK(Na)Mg  1968—1984
nitrogen fertilizer exposure: N2
phosphate fertilizer exposure: P
potassium fertilizer exposure: K
sodium nutrient exposure: Na1
Until 1973
magnesium nutrient exposure: Mg
N[0|1]+3 1/2[PKMg]  1985—2000
nitrogen fertilizer exposure: N3
Applied to strip 17
nitrogen fertilizer exposure: N4
Applied to strip 18
phosphate fertilizer exposure: P
potassium fertilizer exposure: K
magnesium nutrient exposure: Mg
N1+4+1 PKMg  2000—
nitrogen fertilizer exposure: N1+4+1
phosphate fertilizer exposure: P
potassium fertilizer exposure: K
magnesium nutrient exposure: Mg
N1+2+1 PKMg  2001—
nitrogen fertilizer exposure: N1+2+1
phosphate fertilizer exposure: P
potassium fertilizer exposure: K
magnesium nutrient exposure: Mg
C  1968—1988
castor meal exposure: C
N1+1+1 KMg  2001—
nitrogen fertilizer exposure: N1+1+1
potassium fertilizer exposure: K
magnesium nutrient exposure: Mg
N2 K(Na)Mg  1968—2000
nitrogen fertilizer exposure: N2
potassium fertilizer exposure: K
sodium nutrient exposure: Na1
applied until 1973
magnesium nutrient exposure: Mg
N4 KMg  2000—
nitrogen fertilizer exposure: N4
potassium fertilizer exposure: K
magnesium nutrient exposure: Mg