Broadbalk

Local identifier: R/BK/1
Years operational: 1843— (Establishment period end: 1851)
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: Started in 1843, Broadbalk is one of the oldest continuous agronomic experiments in the world. Wheat is grown every year on all or part of the experiment. Established to test the effects of various combinations of inorganic fertilizers (N, P, K, Na and Mg) and organic manures on the yield of winter wheat, many of these treatments continue today. A control strip has received no fertilizer or organic manures since 1843. It was started by Lawes and Gilbert in autumn 1843, and the first crop was harvested in summer 1844.
Farm operation data?
Sample archive?
Samples available?
Data Access Statement: Available online with registration
Data license: CC BY
Data policy: Yes (not online)
Organization: Rothamsted Research
research organisation
People: Dr Andy Macdonald
principal investigator
Rothamsted Research
Sustainable Agricultural Systems
Dr Sarah Perryman
data manager
Rothamsted Research
Computational and Analytical Sciences
res.e-ra@rothamsted.ac.uk
Dr Margaret Glendining
data manager
Rothamsted Research
Computational and Analytical Sciences
res.e-ra@rothamsted.ac.uk

Site: Broadbalk

Type

research station field

Local code

R/BK/1

Location

Harpenden

Hertfordshire

United Kingdom

Geographic location

51.80946, -0.37301

+−

Maps

Satellite

Elevation

130 Metres

Visits permitted?

Yes

Visiting arrangements

Contact Dr 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

Variable	Depth	Value (range)	Units	Ref year
sand content	0 – 23 Centimetres	25	Percent
silt content	0 – 23 Centimetres	50	Percent
clay content	0 – 23 Centimetres	25 (19 – 39)	Percent
soil organic carbon	0 – 23 Centimetres	1	Percent	1843
total soil nitrogen	0 – 23 Centimetres	0.11	Percent	1843
plant available phosphorous (Olsen P)	0 – 23 Centimetres	10	milligram per kilogram	1843
soil bulk density	0 – 23 Centimetres	1.25	gram per cubic centimetre	1843
soil organic carbon	0 – 23 Centimetres	28.8	tonnes per hectare

Climatic type

temperate oceanic climate

Climate description

Mean annual temperature 9.8 degrees C (1981-2010 mean)

Climate properties

Variable	Time period	Value (range)	Units
annual total precipitation	1981 – 2010	733 (515 – 973)	mm
annual mean air temperature	1981 – 2010	9.8	degree Celsius

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 (2.1), 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 plots

Number of harvests per year

Crop

Crop	Years grown
winter wheat

Factors

nitrogen fertilizer exposure Inorganic nitrogen fertilizer in various forms and amounts applied annually Plot application: Whole plot: N1 (48 kgN/ha)
1852—1925
Applied to crop: winter wheat
Application method: broadcast application method
Chemical form: ammonium sulfate
All applied in autumn, 1852-1877, all applied in spring 1878-1883; 24 kgN applied in autumn, remainder applied in spring 1884-1925
N1* (48 kgN/ha)
1852—1925
Applied to crop: winter wheat
Application method: broadcast application method
Chemical form: sodium nitrate
All applied in spring, as one application until 1898, as two equal amounts 1899-1925
N1.5 (72 kgN/ha)
1852—1878
Applied to crop: winter wheat
Application method: broadcast application method
Chemical form: ammonium sulfate
Applied to Plot 19 with rape cake, All applied in autumn
N2 (96 kgN/ha)
1852—1925
Applied to crop: winter wheat
Application method: broadcast application method
Chemical form: ammonium sulfate
All applied in autumn, 1852-1877, all applied in spring 1878-1883; 24 kgN applied in autumn, remainder applied in spring 1884-1925, except to strip 15. Strip 15 N applied in spring 1873-77, N applied in autumn 1878-1925.
N2* (96 kgN/ha)
1852—1925
Applied to crop: winter wheat
Application method: broadcast application method
Chemical form: sodium nitrate
All applied in spring, as one application until 1898, as two equal amounts 1899-1925
N3 (144 kgN/ha)
1852—1925
Applied to crop: winter wheat
Application method: broadcast application method
Chemical form: ammonium sulfate
All applied in autumn, 1852-1877, all applied in spring 1878-1883; 24 kgN applied in autumn, remainder applied in spring 1884-1925
N4 (192 kgN/ha)
1852—1864
Applied to crop: winter wheat
Chemical form: ammonium sulfate
All applied in autumn
FYM exposure FYM from cattle: farmyard manure (35 t/ha)
1843—1925
Applied to crop: winter wheat
Application frequency: Annual
Applied to plot 2b (2.2) from 1843, and to plot 2a (2.1) since 1885. Plot 2a was a new plot made in 1885. FYM is applied in autumn, supplying approx 225 kgN
phosphate fertilizer exposure phosphate fertilizer: P (35 kg/ha)
1843—1925
Applied to crop: winter wheat
Application frequency: annually
Application method: chemical basal application
Chemical form: triple superphosphate
Applied in the autumn, omitted 1915
potassium fertilizer exposure Potassium fertilizer application: K (90 kg/ha)
1843—1925
Applied to crop: winter wheat
Application frequency: annually
Application method: fertilizer basal application
Chemical form: potassium sulphate
Applied in the autumn, omitted 1915, 1917-1919
sodium nutrient exposure sodium fertilizer application: Na (16 kg/ha)
1843—1925
Applied to crop: winter wheat
Application frequency: annually
Application method: fertilizer basal application
Chemical form: sodium sulphate
Applied in the autumn, omitted 1915
magnesium nutrient exposure Magnesium fertilizer application: Mg (11 kg/ha)
1843—1925
Applied to crop: winter wheat
Application frequency: annually
Application method: fertilizer basal application
Chemical form: magnesium sulphate
Applied in the autumn, omitted 1915
rapeseed cake exposure Organic manure supplying approx 96 kgN: C
1852—1926
Applied to crop: winter wheat
Application frequency: annually
Supplying approx 96 kg N (N2).

Factor combinations

FYM 1885—1925
FYM 1843—1925
Nil 1843—1925
PKNaMg 1843—1925: phosphate fertilizer exposure: P
potassium fertilizer exposure: K
sodium nutrient exposure: Na
magnesium nutrient exposure: Mg
N1 PKNaMg 1843—1925: nitrogen fertilizer exposure: N1 (48 kgN/ha)
phosphate fertilizer exposure: P
potassium fertilizer exposure: K
sodium nutrient exposure: Na
magnesium nutrient exposure: Mg
N2 PKNaMg 1852—1925: nitrogen fertilizer exposure: N2
phosphate fertilizer exposure: P
potassium fertilizer exposure: K
sodium nutrient exposure: Na
magnesium nutrient exposure: Mg
N3 PKNaMg 1852—1925: nitrogen fertilizer exposure: N3
phosphate fertilizer exposure: P
potassium fertilizer exposure: K
sodium nutrient exposure: Na
magnesium nutrient exposure: Mg
N1* PKNaMg 1894—1925: nitrogen fertilizer exposure: N1*
phosphate fertilizer exposure: P
potassium fertilizer exposure: K
sodium nutrient exposure: Na
magnesium nutrient exposure: Mg
N4 PKNaMg 1852—1864: nitrogen fertilizer exposure: N4
phosphate fertilizer exposure: P
potassium fertilizer exposure: K
sodium nutrient exposure: Na
magnesium nutrient exposure: Mg
N2* PKNaMg 1884—1925: nitrogen fertilizer exposure: N2*
phosphate fertilizer exposure: P
potassium fertilizer exposure: K
sodium nutrient exposure: Na
magnesium nutrient exposure: Mg
N1.5 PKNaMg +C 1852—1872: nitrogen fertilizer exposure: N1.5
phosphate fertilizer exposure: P
potassium fertilizer exposure: K
sodium nutrient exposure: Na
magnesium nutrient exposure: Mg
rapeseed cake exposure: C

Measurements

Variable	Material	Units	Frequency	Comment
yield components	winter wheat	t/ha	annually	Grain and straw yields at field moisture content. Actual dry matter not measured, assumed to be approximately 85% dry matter.
weight per bushel dressed corn	winter wheat	lb	annually	Bushel weights can be used to derive Hectolitre weights (HLWT),a measure of grain quality.
soil organic carbon	Soil	%	infrequently	Topsoil (0-23cm) from soil sampled in 1865, 1881, 1893 and 1914.
soil organic carbon	Soil	t/ha	infreqently	Topsoil (0-23cm) from soil sampled in 1865, 1881, 1893 and 1914. Calculated from % SOC and soil bulk density; adjusted for changes in bulk density in strips given FYM
soil total nitrogen	Soil	%	infrequently	Topsoil (0-23cm) from soil sampled in 1865, 1881, 1893 and 1914.
plant available phosphorous	Soil	mg/kg	infrequently	Sodium bicarbonate soluble P (Olsen P). Topsoil (0-23cm) from soil sampled in 1865, 1881, 1893 and 1914.
soil bulk density	Soil	g/cm3	infrequently	A single mean value for all plots which do not receive FYM and estimated values for plots which receive FYM, based on measurements made in 1865, 1881, 1893 (Dyer, 1902), 1914 (unpublished) and 2000 (Watts et al, 2006).
harvest date	winter wheat		annually	Includes both cutting and carting date, ie dates crop cut and then removed from the field.

Design period: Middle period (1926—1967)

Design Type

Demonstration strip design

Description

In 1926 the experiment was divided into five sections (I-V) which were bare fallowed in sequence to control weeds, usually one year in five.

Design description

19 fertilizer treatment strips divided into five sections in 1926 (I-V) crossing all the treatment strips. In 1955 Section I was divided into Ia and Ib; Ia in continuous wheat, no fallow, Ib continued in the fallow rotation. In 1955 Section V was divided into Va and Vb. Va continued in the fallow rotation, with no herbicides applied. Vb received lime in 1955, and became continuous wheat with no further fallows from 1959.

Number of plots

Number of subplots

Number of harvests per year

Crops

Crop	Years grown
winter wheat
fallow

Factors

nitrogen fertilizer exposure Inorganic nitrogen fertilizer in various forms and amounts applied annually: N1 (48 kg/ha)
1926—1967
Applied to crop: winter wheat
Application frequency: twice
Application method: broadcast application method
Chemical form: ammonium sulfate
24kgN applied in autumn, remainder in spring
N2 (96 kg/ha)
1926—1967
Applied to crop: winter wheat
Application frequency: twice
Application method: broadcast application method
Chemical form: ammonium sulfate
24kgN applied in autumn, remainder in spring
N3 (144 kg/ha)
1926—1967
Applied to crop: winter wheat
Application frequency: twice
Application method: broadcast application method
Chemical form: ammonium sulfate
24kgN applied in autumn, remainder in spring
N1* (48 kg/ha)
1926—1967
Applied to crop: winter wheat
Application frequency: twice
Application method: broadcast application method
Chemical form: sodium nitrate
Applied in spring as two equal amounts
N2* (96 kg/ha)
1926—1967
Applied to crop: winter wheat
Application frequency: twice
Application method: broadcast application method
Chemical form: sodium nitrate
Applied in spring as two equal amounts
FYM exposure FYM from cattle: farmyard manure (35 t/ha)
1926—1967
Applied to crop: winter wheat
Application frequency: Once a year
Applied to strips 2.1 (2a) and 2.2 (2b). Not applied in the fallow years

Factor combinations

FYM 1926—1965: FYM exposure: farmyard manure

Measurements

Variable	Material	Units	Frequency	Comment
yield components	winter wheat	t/ha	annually	Grain and straw yields at field moisture content, approximately 85% dry matter.
weight per bushel dressed corn	winter wheat	lb	annually	Bushel weights can be used to derive hectolitre weights (HLWT), a measure of grain quality
soil organic carbon	Soil	%	infrequently	Topsoil (0-23cm) from soil sampled in 1936; 1944 and 1966.
total soil nitrogen	Soil	%	infrequently	Topsoil (0-23cm) from soil sampled in 1936; 1944 and 1966.
plant available phosphorous	Soil	mg/kg	infrequently	Sodium bicarbonate soluble P (Olsen P). Topsoil (0-23cm) from soil sampled in 1936, 1944 and 1966
soil bulk density	Soil	g/cm3	infrequently	A single mean value for all plots which do not receive FYM and estimated values for plots which receive FYM, based on measurements made in 1865, 1881, 1893 (Dyer, 1902), 1914 (unpublished) and 2000 (Watts et al, 2006).
soil organic carbon	Soil	t/ha	infrequently	Topsoil (0-23cm) from soil sampled in 1936, 1944 and 1966. Calculated from % SOC and soil bulk density; adjusted for changes in bulk density in strips given FYM
weed species richness	Not specified			Species occurence, selected plots and selected years for all sections (before herbicides were applied)
harvest date	winter wheat		annually	Both cutting date and carting date (ie date crop removed from field)

Design period: Current period (1968—)

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

Crops

Crop	Years 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

F-P-W 1979—1983

1
fallow
2
potatoes
3
winter wheat

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

Measurements

Variable	Material	Units	Frequency	Comment
yield components	All crops	t/ha	annually	Grain and straw at 85% dry matter.
hectolitre grain weight	winter wheat	kilogram per hectolitre	annually	Since 1999 selected plots only
thousand grain weight	winter wheat	gram	annually	Since 1974 selected plots only
weed species richness	Not specified		annually	Section 8 only (no herbicides)
soil organic carbon	Soil	percent	every five years from 1987	Topsoil (0-23cm)
soil total nitrogen	Soil	percent	every five years from 1987	Topsoil (0-23cm)
plant available phosphorous	Soil	mg/kg	every five years for 1987	Topsoil (0-23cm)
soil bulk density	Soil	gram per cubic centimeter		A single mean value for all plots which do not receive FYM and estimated values for plots which receive FYM, based on measurements made in 1865, 1881, 1893 (Dyer, 1902), 1914 (unpublished) and 2000 (Watts et al, 2006).
nutrient content	All crops	percent	annually	Selected plots since 1968 % N, P, K, Ca, Mg, Na and S. Grain and straw.
take-all disease incidence	winter wheat		annually	Selected plots since 1968. Also eyespot, sharp eyespot and brown foot rot.
harvest date	All crops		annually	Sowing and harvest dates of all crops
earthworm abundance	Not specified		occasional	Selected plots, occasional years.

Related publications

Broadbalk mean long-term winter wheat grain yields, selected treatments
https://doi.org/10.23637/KeyRefOABKyields. [In English]
Long-term changes in Broadbalk soil organic carbon content, selected treatments
https://doi.org/10.23637/KeyRefOABKsoc [In English]
Long-term changes in Broadbalk soil total nitrogen content, selected treatments
https://doi.org/10.23637/bk-oadata-soiln-01 [In English]
Long-term changes in Broadbalk Olsen P in topsoil, selected treatments.
https://doi.org/10.23637/KeyRefOABKolsenP [In English]
Fisher 1921 Broadbalk wheat grain yields 1852-1918.
https://doi.org/10.23637/rbk1-data-fisher-1921-01 [In English]
Cirsium arvense frequency on Broadbalk Section 8 1991-2018.
https://doi.org/10.23637/bbk-2078416917-01 [In English]
Broadbalk experiment web page
http://www.era.rothamsted.ac.uk/Broadbalk [In English]

Broadbalk

Site: Broadbalk

Design period: Early period (1852—1925)

N1 (48 kgN/ha)

N1* (48 kgN/ha)

N1.5 (72 kgN/ha)

N2 (96 kgN/ha)

N2* (96 kgN/ha)

N3 (144 kgN/ha)

N4 (192 kgN/ha)

farmyard manure (35 t/ha)

P (35 kg/ha)

K (90 kg/ha)

Na (16 kg/ha)

Mg (11 kg/ha)

C

phosphate fertilizer exposure: P

potassium fertilizer exposure: K

sodium nutrient exposure: Na

magnesium nutrient exposure: Mg

nitrogen fertilizer exposure: N1 (48 kgN/ha)

phosphate fertilizer exposure: P

potassium fertilizer exposure: K

sodium nutrient exposure: Na

magnesium nutrient exposure: Mg

nitrogen fertilizer exposure: N2

phosphate fertilizer exposure: P

potassium fertilizer exposure: K

sodium nutrient exposure: Na

magnesium nutrient exposure: Mg

nitrogen fertilizer exposure: N3

phosphate fertilizer exposure: P

potassium fertilizer exposure: K

sodium nutrient exposure: Na

magnesium nutrient exposure: Mg

nitrogen fertilizer exposure: N1*

phosphate fertilizer exposure: P

potassium fertilizer exposure: K

sodium nutrient exposure: Na

magnesium nutrient exposure: Mg

nitrogen fertilizer exposure: N4

phosphate fertilizer exposure: P

potassium fertilizer exposure: K

sodium nutrient exposure: Na

magnesium nutrient exposure: Mg

nitrogen fertilizer exposure: N2*

phosphate fertilizer exposure: P

potassium fertilizer exposure: K

sodium nutrient exposure: Na

magnesium nutrient exposure: Mg

nitrogen fertilizer exposure: N1.5

phosphate fertilizer exposure: P

potassium fertilizer exposure: K

sodium nutrient exposure: Na

magnesium nutrient exposure: Mg

rapeseed cake exposure: C

Design period: Middle period (1926—1967)

N1 (48 kg/ha)

N2 (96 kg/ha)

N3 (144 kg/ha)

N1* (48 kg/ha)

N2* (96 kg/ha)

farmyard manure (35 t/ha)

FYM exposure: farmyard manure

Design period: Current period (1968—)

N1 (48 kgN/ha)

N2 (96 kgN/ha)

N3 (144 kgN/ha)

N4 (192 kgN/ha)

N5 (240 kgN/ha)

N6 (288 kgN/ha)

N1+1+1 (144 kgN/ha)

N1+2+1 (192 kgN/ha)

N1+3+1 (240 kgN/ha)

N1+4+1 (288 kgN/ha)

K (90 kgK/ha)

K2 (180 kgK/ha)

K* (90 kgK/ha)

P (35 kgP/ha)

Na1 (16 kgNa/ha)