Broadbalk

  • Experiment Code: R/BK/1
  • Experiment Site: Rothamsted
  • Objectives: 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.
  • Date Start: 1843
  • Establisment Period End: 1851
  • Date End: Ongoing

Key Contacts

  • Andy Macdonald

  • Role: Principal Investigator
  • Organisation: Rothamsted Research
  • Address: West Common, Harpenden, Hertfordshire, AL5 2JQ, United Kingdom
  • Sarah Perryman

  • Role: Data Manager
  • Organisation: Rothamsted Research
  • Address: West Common, Harpenden, Hertfordshire, AL5 2JQ, United Kingdom
  • Margaret Glendining

  • Role: Data Manager
  • ORCID: https://orcid.org/0000-0002-6466-4629
  • Organisation: Rothamsted Research
  • Address: West Common, Harpenden, Hertfordshire, AL5 2JQ, United Kingdom

Funding

Experimental 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.

Design

  • Period: 1852 - 1925
  • Number of Blocks: 19
  • Number of Replicates: 1
  • Number of Harvests per Year: 1

Crops

Crop Years Grown
Winter Wheat

Factors

Factors are the interventions or treatments which vary across the experiment.

Nitrogen Fertilizer Exposure

Description: Inorganic nitrogen fertilizer in various forms and amounts applied annually

Application: Whole Plot

Levels
Level Name Amount Years Frequency Crop Method Chemical Form Notes
N1 48 kgN/ha 1852 - 1925 winter wheat broadcast application method 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 winter wheat broadcast application method sodium nitrate All applied in spring, as one application until 1898, as two equal amounts 1899-1925
N1. 5 72 kgN/ha 1852 - 1878 winter wheat broadcast application method ammonium sulfate Applied to Plot 19 with rape cake, All applied in autumn
N2 96 kgN/ha 1852 - 1925 winter wheat broadcast application method 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 winter wheat broadcast application method sodium nitrate All applied in spring, as one application until 1898, as two equal amounts 1899-1925
N3 144 kgN/ha 1852 - 1925 winter wheat broadcast application method 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 annually winter wheat broadcast application method ammonium sulfate All applied in autumn

Fym Exposure

Description: FYM from cattle

Levels
Level Name Amount Years Frequency Crop Method Chemical Form Notes
Farmyard Manure 35 t/ha 1843 - 1925 Annual winter wheat 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

Description: phosphate fertilizer

Levels
Level Name Amount Years Frequency Crop Method Chemical Form Notes
P 35 kg/ha 1843 - 1925 annually winter wheat chemical basal application triple superphosphate Applied in the autumn, omitted 1915

Potassium Fertilizer Exposure

Description: Potassium fertilizer application

Levels
Level Name Amount Years Frequency Crop Method Chemical Form Notes
K 90 kg/ha 1843 - 1925 annually winter wheat fertilizer basal application potassium sulphate Applied in the autumn, omitted 1915, 1917-1919

Sodium Nutrient Exposure

Description: sodium fertilizer application

Levels
Level Name Amount Years Frequency Crop Method Chemical Form Notes
Na 16 kg/ha 1843 - 1925 annually winter wheat fertilizer basal application sodium sulphate Applied in the autumn, omitted 1915

Magnesium Nutrient Exposure

Description: Magnesium fertilizer application

Levels
Level Name Amount Years Frequency Crop Method Chemical Form Notes
Mg 11 kg/ha 1843 - 1925 annually winter wheat fertilizer basal application magnesium sulphate Applied in the autumn, omitted 1915

Rapeseed Cake Exposure

Description: Organic manure supplying approx 96 kgN

Levels
Level Name Amount Years Frequency Crop Method Chemical Form Notes
C 96 kgN/ha 1852 - 1926 annually winter wheat Supplying approx 96 kg N (N2).

Factor Combinations

Factor Combinations are the combination of factors applied to different plots on the experiment.

Factor Combination Time Coverage Notes
FYM 1885 - 1925 Applied to plot 2a (2.1), which was created in 1885.
FYM 1843 - 1925 Applied to plot 2b (2.2), originally called plot 2, named plot 2b in 1885 when plot 2a was created.
Nil 1843 - 1925 Strip 3. Originally 2 half plots, 3 (nil since 1844) and 4 (1844-51 NP; since 1852 nil). Harvested separately until 1899. Strip 16 received nil 1865-1883
PKNaMg 1843 - 1925 Strip 5
N1 PKNaMg 1843 - 1925 Strip 6
N2 PKNaMg 1852 - 1925 Strip 7, also Strip 15a 1852-1872, Strip 15 1873-1925, but N applied at different times to strip 7. Strip 15 was divided into 15a and 15b which received different fertilizer treatments until 1873.
N3 PKNaMg 1852 - 1925 Strip 8
N1* PKNaMg 1894 - 1925 Strip 9, split into 9a and 9b, 1852-1893 receiving different treatments. 9a received N1*/N2* plus PKNaMg, 9b received only N2*/N1*.
N4 PKNaMg 1852 - 1864 Strip 16, which then received nil 1865-1883 and N2*PKNaMg since 1884
N2* PKNaMg 1884 - 1925 Strip 16; previously received N4 PKNaMg (1852-1864) and nil (1865-1883)
N1.5 PKNaMg +C 1852 - 1872 Strip 15b. After 1872 strip 15a and 15b combined and received the same fertilizer treatments N2 PKNaMg

Measurements

Variable Unit Collection
Frequency
Material Description Crop
Yield Components t/ha annually SpecifiedCrop Grain and straw yields at field moisture content. Actual dry matter not measured, assumed to be approximately 85% dry matter. winter wheat
Weight per Bushel Dressed Corn lb annually SpecifiedCrop Bushel weights can be used to derive Hectolitre weights (HLWT),a measure of grain quality. winter wheat
Soil Organic Carbon % infrequently Soil Topsoil (0-23cm) from soil sampled in 1865, 1881, 1893 and 1914.
Soil Organic Carbon t/ha infreqently Soil 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 % infrequently Soil Topsoil (0-23cm) from soil sampled in 1865, 1881, 1893 and 1914.
Plant Available Phosphorous mg/kg infrequently Soil Sodium bicarbonate soluble P (Olsen P). Topsoil (0-23cm) from soil sampled in 1865, 1881, 1893 and 1914.
Soil Bulk Density g/cm3 infrequently Soil 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 annually SpecifiedCrop Includes both cutting and carting date, ie dates crop cut and then removed from the field. winter wheat

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.

Design

  • Period: 1926 - 1967
  • Number of Blocks: 19
  • Number of Sub-plots:
  • Number of Harvests per Year: 1

Crops

Crop Years Grown
Winter Wheat
Fallow

Factors

Factors are the interventions or treatments which vary across the experiment.

Nitrogen Fertilizer Exposure

Description: Inorganic nitrogen fertilizer in various forms and amounts applied annually

Levels
Level Name Amount Years Frequency Crop Method Chemical Form Notes
N1 48 kg/ha 1926 - 1967 twice winter wheat broadcast application method ammonium sulfate 24kgN applied in autumn, remainder in spring
N2 96 kg/ha 1926 - 1967 twice winter wheat broadcast application method ammonium sulfate 24kgN applied in autumn, remainder in spring
N3 144 kg/ha 1926 - 1967 twice winter wheat broadcast application method ammonium sulfate 24kgN applied in autumn, remainder in spring
N1* 48 kg/ha 1926 - 1967 twice winter wheat broadcast application method sodium nitrate Applied in spring as two equal amounts
N2* 96 kg/ha 1926 - 1967 twice winter wheat broadcast application method sodium nitrate Applied in spring as two equal amounts

Fym Exposure

Description: FYM from cattle

Levels
Level Name Amount Years Frequency Crop Method Chemical Form Notes
Farmyard Manure 35 t/ha 1926 - 1967 Once a year winter wheat Applied to strips 2.1 (2a) and 2.2 (2b). Not applied in the fallow years

Factor Combinations

Factor Combinations are the combination of factors applied to different plots on the experiment.

Factor Combination Time Coverage Notes
FYM 1926 - 1965

Measurements

Variable Unit Collection
Frequency
Material Description Crop
Yield Components t/ha annually SpecifiedCrop Grain and straw yields at field moisture content, approximately 85% dry matter. winter wheat
Weight per Bushel Dressed Corn lb annually SpecifiedCrop Bushel weights can be used to derive hectolitre weights (HLWT), a measure of grain quality winter wheat
Soil Organic Carbon % infrequently Soil Topsoil (0-23cm) from soil sampled in 1936; 1944 and 1966.
Total Soil Nitrogen % infrequently Soil Topsoil (0-23cm) from soil sampled in 1936; 1944 and 1966.
Plant Available Phosphorous mg/kg infrequently Soil Sodium bicarbonate soluble P (Olsen P). Topsoil (0-23cm) from soil sampled in 1936, 1944 and 1966
Soil Bulk Density g/cm3 infrequently Soil 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 t/ha infrequently Soil 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 Species occurence, selected plots and selected years for all sections (before herbicides were applied)
Harvest Date annually SpecifiedCrop Both cutting date and carting date (ie date crop removed from field) winter wheat

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.

Design

  • Period: 1968 - Now
  • Number of Harvests per Year: 1

Crops

Crop Years Grown
Winter Wheat1968 -
Oats1996 -
Spring Beans1968 - 1978
Potatoes1968 - 1996
Winter Beans2018 -
Fallow
Maize1997 - 2017

Crop Rotations

Rotation Crops
continuous wheat (1968 - ) Winter Wheat
P-BE-W (1968 - 1979) Potatoes > Spring Beans > Winter Wheat
F-W-W (1968 - 1981) Fallow > Winter Wheat > Winter Wheat
F-P-W (1979 - 1983) Fallow > Potatoes > Winter Wheat
F-P-W-W-W (1982 - 1999) Fallow > Potatoes > Winter Wheat > Winter Wheat > Winter Wheat
O-M-W-W-W (1996 - 2017) Oats > Maize > Winter Wheat > Winter Wheat > Winter Wheat
W-W-O-W-Be (2018 - ) Winter Wheat > Winter Wheat > Oats > Winter Wheat > Winter Beans

Factors

Factors are the interventions or treatments which vary across the experiment.

Nitrogen Fertilizer Exposure

Description: 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.

Application: Whole Plot

Levels
Level Name Amount Years Frequency Crop Method Chemical Form Notes
N1 48 kgN/ha 1968 - annually in mid-April winter wheat Applied to wheat, maize, spring beans, since 2018 oats at half rate. Not applied to fallow or beans from 2018.
N2 96 kgN/ha 1968 - annually in mid-April winter wheat ammonium nitrate
N3 144 kgN/ha 1968 - annually in mid-April winter wheat ammonium nitrate
N4 192 kgN/ha 1968 - annually in mid-April winter wheat ammonium nitrate
N5 240 kgN/ha 1985 - annually in mid-April winter wheat ammonium nitrate
N6 288 kgN/ha 1985 - annually in mid-April winter wheat ammonium nitrate
N1+1+1 144 kgN/ha 2001 - mid-March, mid-April, Mid-May winter wheat ammonium nitrate N2+1 for maize
N1+2+1 192 kgN/ha 2001 - mid-March, mid-April, Mid-May winter wheat ammonium nitrate N2+2 for maize
N1+3+1 240 kgN/ha 2001 - mid-March, mid-April, Mid-May winter wheat ammonium nitrate N2+3 for maize
N1+4+1 288 kgN/ha 2001 - mid-March, mid-April, Mid-May winter wheat ammonium nitrate N2+4 for maize

Potassium Fertilizer Exposure

Application: Whole Plot

Levels
Level Name Amount Years Frequency Crop Method Chemical Form Notes
K 90 kgK/ha 1968 - annually in autumn potassium sulphate
K2 180 kgK/ha 2001 - 2005 annually in autumn potassium sulphate
K* 90 kgK/ha 2001 - Annually in autumn potassium chloride

Phosphate Fertilizer Exposure

Application: Whole Plot

Levels
Level Name Amount Years Frequency Crop Method Chemical Form Notes
P 35 kgP/ha 1968 - Annually in autumn calcium bis(dihydrogenphosphate)

Sodium Nutrient Exposure

Application: Whole Plot

Levels
Level Name Amount Years Frequency Crop Method Chemical Form Notes
Na1 16 kgNa/ha 1968 - 1973 Annually in autumn sodium sulphate
Na2 55 kgNa/ha 1968 - 2000 Annually in autumn sodium sulphate 57 kgNa/ha until 1973

Magnesium Nutrient Exposure

Application: Whole Plot

Levels
Level Name Amount Years Frequency Crop Method Chemical Form Notes
Mg 12 kgMg/ha 1968 - Annually in autumn magnesium sulphate 11kgMg until 1973. 35 kgMg every 3rd year 1974-2000.
Mg2 24 kgMg/ha 2001 - 2005 Annually in autumn magnesium sulphate Plus 60 kg Mg in autumn 2000 only
Mg* 30 kgMg/ha 1968 - 2000 Annually in autumn magnesium sulphate 31kgMg as magnesium sulphate until 1973

Farmyard Manure Exposure

Description: From cattle

Application: Whole Plot

Levels
Level Name Amount Years Frequency Crop Method Chemical Form Notes
Fym 35 t/ha 1968 - Annually in autumn winter wheat Derived from cattle. Not applied to beans from 2018, not applied to oats 1996-2017.
Residual Fym 2001 - Plots previously receiving FYM

Castor Meal Exposure

Application: Whole Plot

Levels
Level Name Amount Years Frequency Crop Method Chemical Form Notes
C 96 kgN/ha 1968 - 1988
Residual C - Plots previously receiving

Factor Combinations

Factor Combinations are the combination of factors applied to different plots on the experiment.

Factor Combination Time Coverage Notes
FYM N2 PK 1968 - 1984 Applied to strip 01
FYM N4 PK 1985 - 2000 Applied to strip 01
(FYM) N4 2001 - Applied to strip 01
FYM N2 1968 - 2004 Applied to strip 2.1
FYM N3 2005 - Applied to strip 2.1
FYM 1968 - Applied to strip 2.2
Nil 1968 - No organic or inorganic amendments, strip 03
(P)K(Na)Mg 1968 - 1973 Applied to strip 05
N1 (P)K(Na)Mg 1968 - Applied to strip 06
N2 (P)K(Na)Mg 1968 - Applied to strip 07 and applied to strip 16 until 1984
N3 (P)K(Na)Mg 1968 - Applied to strip 08, and applied to strip 15 until 1984
N4 (P)K(Na)Mg 1968 - Applied to strip 09
N2 1968 - 2000 Applied to strip 10
N4 2001 - Applied to strip 10
N2 P 1968 - 2000 Applied to strip 11
N4 PMg 2001 - Applied to strip 11
N2 PNa 1968 - 2000 Applied to strip 12
N1+3+1 (P)K2Mg2 2001 - 2005 Applied to strip 12. P was not applied in this period
N1+3+1 (P)KMg 2006 - Applied to plot 12
N2 PK 1968 - 2000 Applied to plot 13
N4 PK 2001 - Applied to strip 14
N2 PKMg* 1968 - 2000 Applied to plot 14
N4 PK* 2001 - Applied to strip 14
N5 (P)KMg 1985 - Applied to strip 15
N6 (P)KMg 1985 - Applied to plot 16
N2 1/2[PK(Na)Mg 1968 - 1984 Applied to strips 17 and 18 in alternate years
N[0|1]+3 1/2[PKMg] 1985 - 2000 Applied to strips 17 and 18 in alternate years
N1+4+1 PKMg 2000 - Applied to strip 17
N1+2+1 PKMg 2001 - Applied to strip 18
C 1968 - 1988 Applied to strip 19
N1+1+1 KMg 2001 - Applied to strip 19
N2 K(Na)Mg 1968 - 2000 Applied to strip 20
N4 KMg 2000 - Applied to strip 20

Measurements

Variable Unit Collection
Frequency
Material Description Crop
Yield Components t/ha annually AllCrops Grain and straw at 85% dry matter.
Hectolitre Grain Weight annually SpecifiedCrop Since 1999 selected plots only winter wheat
Thousand Grain Weight annually SpecifiedCrop Since 1974 selected plots only winter wheat
Weed Species Richness annually Section 8 only (no herbicides)
Soil Organic Carbon every five years from 1987 Soil Topsoil (0-23cm)
Soil Total Nitrogen every five years from 1987 Soil Topsoil (0-23cm)
Plant Available Phosphorous mg/kg every five years for 1987 Soil Topsoil (0-23cm).
Soil Bulk Density Soil 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 annually AllCrops Selected plots since 1968 % N, P, K, Ca, Mg, Na and S. Grain and straw.
Take-all Disease Incidence annually SpecifiedCrop Selected plots since 1968. Also eyespot, sharp eyespot and brown foot rot. winter wheat
Harvest Date annually AllCrops Sowing and harvest dates of all crops
Earthworm Abundance occasional Selected plots, occasional years.

Site: Broadbalk - Rothamsted

  • Experiment Site: Rothamsted
  • Description: The site has probably been occupied since Roman times, and the Rothamsted map of 1623 shows the site under arable cultivation. 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. There is no irrigation. The plough layer (0-23 m) is limed when necessary to maintain a minimum soil pH of 7.0 – 7.5.
  • Visit Permitted?: Yes
  • Visiting Arrangments: Contact Dr Andy Macdonald
  • Elevation: 130 Metres
  • Geolocation:    51.80946, -0.37301

Soil

  • Type: Luvisol
    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 Value Reference Year Is Estimated Is Baseline
Sand content 25% (Percent) NO NO
Silt content 50% (Percent) NO NO
Clay content 25% (Percent) NO NO
Soil organic carbon 1% (Percent) 1843 YES NO
Total soil nitrogen 0.11% (Percent) 1843 YES NO
Plant available phosphorous (Olsen P) 10mg/kg (milligram per kilogram) 1843 YES NO
Soil bulk density 1.25g/cm3 (gram per cubic centimetre) 1843 YES NO
Soil organic carbon 28.8t/ha (tonnes per hectare) YES NO

Datasets available

Crop yield data

Broadbalk mean long-term winter wheat yields
Crop yield data Mean long-term winter wheat yields from selected treatments on Broadbalk 1852-2016, reflecting the improved treatments and agronomic practices introduced on Broadbalk such as modern cultivars, better control of pests, diseases and weeds, especially since the 1960s.
OAWWYields
Broadbalk Wheat Experiment mean annual grain and straw yields 1852-1925
Crop yield data Mean annual grain and straw yields for each treatment strip of the Broadbalk Wheat Experiment, 1852-1925. Also other agronomic information, including sowing and harvest dates, amount, type and date of application of treatments, and winter wheat cultivars.
YIELD852925
Fisher 1921 Broadbalk wheat grain yields 1852-1918
Crop yield data This dataset consists of annual wheat yields from selected plots of the Broadbalk Wheat Experiment, 1852-1918, as used by R. A. Fisher in his 1921 paper 'Studies in crop variation'.
FISHER1921

Crop nutrient data

Broadbalk Crop Nutrient Content, Wheat 1968-2017
Crop nutrient data From 1968 Broadbalk was divided into 10 sections. Grain and straw from selected sections and plots were collected and stored in the Sample Archive. They were analysed for nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sodium (Na) and sulphur (S).
BKNUTRW

Disease data

Broadbalk Wheat Experiment brown foot rot (Fusarium spp.) 1992-2009
Disease data This dataset contains scores of Brown Foot Rot (BFR) caused by _Fusarium_ spp. , from the Broadbalk wheat experiment, with associated grain yield at harvest, 1992-2009. BFR infection varied a lot from year to year, possibly due to variation in winter and spring temperature and rainfall.
BKBFR

Soil data

Broadbalk soil organic carbon content 1843-2015
Soil data Long-term changes in soil organic carbon content (t/ha) in selected treatments of the Broadbalk experiment, where winter wheat has been grown every year since autumn 1843. SOC in t/ha, calculated from %SOC and soil weights, adjusted for changes in soil bulk density in FYM treatments.
BKSOC1843
Broadbalk Soil Total % Nitrogen Content, 1843-2010
Soil data Long-term changes in total % nitrogen concentration in the topsoil (0-23 cm) in selected treatments of the Broadbalk experiment, where winter wheat has been grown most years since 1843 (continuous wheat).
Nitro1843
Broadbalk changes in Olsen P in top soil, 1843-2010
Soil data Summary data showing changes in plant-available phosphorus (Olsen P) in the topsoil (0-23cm) of selected plots of the Broadbalk Wheat experiment, 1843-2010.
OAOlsenP1844

Species observation data

Cirsium arvense frequency on Broadbalk Section 8 1991-2018
Species observation data This dataset consists of the relative frequencies of Cirsium arvense (Creeping thistle) of the Family Asteraceae recorded on Section 8 plots of the Broadbalk Wheat Experiment, 1991-2018. Section 8 has not received any herbicides in its history.
CIRSIUM1991
Additional data is available through e-RAdata. Please register for access.

More about Broadbalk

Plans and treatments:
Experimental plans, fertilizer treatments and cropping details, 1852-present
Disease surveys:
Information about the wheat root and stem diseases assessed (take-all, eyespot, sharp eyespot and brown foot rot)
Weeds surveys:
Information about the weed surveys on Section 8 (no herbicides), 1991-present, and earlier surveys on the whole experiment, 1933-1979.
Crop nutrient content:
Information about analytical methods for crop macro nutrient content (% N, P, K, Ca, Mg, Na and S)
Grain quality assessment:
Description of what grain quality data is available (TGWs, Hagberg falling number, Hectolitre weights, grain size categories), and analytical methods used
Soil physical properties and site details:
Site details, plot area, soil moisture and drainage, soil description and texture and soil weights
Soil chemical properties:
Details of which soil chemical properties have been measured, analytical methods used and soil sampling methods
Wheat yield background information:
Description of harvest methods and datasets available
Other crops and fallow:
Description of potatoes, oats, beans and forage maize crops grown on Broadbalk, and the management of the fallow
Earthworms:
Information about earthworm measurements on Broadbalk
See a Video on the Broadbalk Experiment

Broadbalk soil chemical properties background information

The Broadbalk wheat experiment, established in the autumn of 1843, has been cultivated since at least 1623, and probably much earlier (Avery & Bullock, 1969). Soil chemical properties have been measured at regular intervals since 1865.

Soil pH: The plough layer (0-23 m) is limed when necessary to maintain a minimum soil pH of 7.0 7.5. Broadbalk was first limed regularly from 1955-1967, with plots given the larger inputs of ammonium fertilizers receiving more lime than the controls. Liming stopped from 1968-1975, but began again in 1976-1992, with 3 or 4 sections being limed each year. From 2007 onward selected plots have been limed every 5-6 years based on soil pH measurements to maintain top-soil pH around 7.0-7.5. Selected plots were limed in autumn 2018.

Data available

Soil chemical properties have been measured at regular intervals on Broadbalk since 1865, in topsoils (0-23cm) and subsoils. See soil measurements 1843-1944 and soil measurements 1966-2017 for details of what data is available. Not all plots, sections or soil depths have been measured every year. The following soil chemical properties have been measured:

  • %N : total soil Nitrogen %
  • %SOC : soil organic Carbon %
  • Olsen P : plant-available phosphorus, by extraction with a solution of 0.5M NaHCO3, buffered at pH 8.5
  • pH : soil pH in water (1:2.5 soil : solution)
  • Exchangeable cations : exchangeable Ca, K, Mg and Na by extraction with 1M ammonium acetate solution
  • % inorganic carbon (CaCO3-C) : by calcimetry
  • soil weights : see soil physical properties for details

Soil Sampling

Broadbalk soil has been sampled on many occasions over the years. However, because the method of sampling has changed and the experiment has been divided, first into two halves, then into five sections and finally into 10 sections, it is not always advisable to directly compare one sampling with another without careful thought. This table shows, where possible, how samples taken over time relate to each other. Selected plots and depths have been sampled on other occasions; most samples still exist in the Sample Archive.

Since 1992 a systemic sampling plan has been adopted. In 1992, 1997, 2005, 2010 and 2015 all five continuous wheat sections were sampled (0, 1, 6, 8 and 9). In the intervening years the remaining sections in rotation were sampled, one per year, so that all sections were sampled every five years. All sections were sampled in 2000 prior to treatment changes being introduced. See table for full details.

In autumn 2004 it was apparent that parts of the field had been ploughed slightly deeper than 23cm as sub-soil clay was visible in random patches across the field. Thus in 2005 and 2006 all plots were resampled to create a new baseline, if necessary, for soil chemical properties. The sections were then sampled systematically from 2008 onwards.

In 2000-2004 archived soil samples from selected plots sampled in 1865, 1881, 1893, 1914, 1936 and 1944 were re-analysed for soil pH, Olsen-P, exchangeable cations, Total %N, %SOC and CaCO3-C. Values for %N and %SOC from the re-analysis of the 1865 samples were very different to the original data and the 1881 and 1893 re-analysed soils, so the original data was used.

Data before 1926 (when the experiment was divided into sections) are given for whole plots only, from the re-analysis in 2000/2004. More recent data are available for individual plots within each section.

1936, 1944 and 1966 data is included with later data, although the experiment was not divided into 10 sections until 1968.

1936 data: 10-20 cores taken with a narrow auger from each of the five Old Sections were bulked within each plot. Data for Old Section I is used for current sections 0 and 1, Old Section II for current sections 2 and 3, etc. (see soil sampling plan for more details). All the data is from the re-analysis of old samples in 2001-2002.

1944 data: four holes were taken from each of the (then) five Old Sections; holes 1 & 2 were on current Section 0, holes 3 & 4 on current Section 1 etc, so the data can confidently be allocated to the modern sections. Data is presented as the mean of the two holes for the topsoil. Subsoil data is not available for each modern section, as the samples were bulked from four-sub-samples for each of the five old sections. Data for Old Section I is used for current sections 0 and 1, Old Section II for Sections 2 and 3, etc. (see soil sampling plan for more details). The soil was re-analysed in 2003-5 from selected plots from all Sections and depths. All data is from the re-analysis except %CaCO3 which was analysed in 1944. Soil pH and Exchangeable Na were not measured in the 1944 subsoil samples.

1966 data: Section 0 and 1 use data from Old Sections Ia and Ib respectively; Sections 2 and 3 use data from Old Section II; Sections 4 and 5 use data from Old Section III; Sections 6 & 7 use data from Old Section IV; Sections 8 and 9 use data from Old Sections Va and Vb respectively. Bulked Va and Vb samples (ie Sections 8 and 9) were used to determine %SOC (plots 2.1 and 2.2 only) and for all plots for Olsen P, %CaCO3 and Exchangeable K. There was no plot 1 in 1966, this was created in 1968. The soil was sampled in September 1966 but no day is given. It is shown as 15/09/1966 in the database.

Data from the samplings in 2001-2004 is not included as this only covered sections 2, 4, 5 and 7 and there was a comprehensive sampling of all sections in 2000 and then in 2005/6.

Soil Sampling Methods

Samples between 1865 and 1914 were taken with an open-ended metal box, 9 inches (23cm) deep and usually 6 x 6 inches (15 x 15cm) across. There were between three and eight sample positions on each plot which were bulked together for each depth on each plot. In 1944 a spade was used to sample the 0-23cm layer, and the subsoil (23-46cm) was sampled with a semi-cylindrical auger.

In 1936 and from 1966 onwards samples were taken with a semi-cylindrical auger. 10-20 cores were taken from the different soil layers for each individual plot within each section and bulked together for each plot. Small diameter cores taken by semi-cylindrical augers cannot be used to determine soil weights, but provided enough are taken the sample better represents the proportions of SOC, N, P, K etc in the soil than a few large box samples. See soil physical properties for details of soil weights.

Samples were taken in the autumn, after the crop had been removed, but before ploughing, except for Section 3, 1996 which was sampled in March.

Broadbalk sampling
Soil sampling Broadbalk 1943

Non-herbicide plot section 8 Broadbalkp
Soil sampling Broadbalk 1943

Broadbalk sampling
Broadbalk ploughing in 2013

Analysis methods for soil chemical properties

All soil samples are air-dried and sieved <2mm. Data are given for air-dried soil (approximately 98% dry matter). When calculating total amounts in the soil (e.g. kg N ha-1 ) you may wish to convert to oven-dry soil (i.e. 100% dry matter). Broadbalk standard soil weights are given for oven-dry soil.

For information on current analytical methods used for the Rothamsted Long-term experiments, please contact the Rothamsted Research Analytical Chemistry Unit - Harpenden laboratory,

Total soil % nitrogen (%N)

1865: Original soda lime analysis for total N (Johnston, 1969b, table 5.10) multiplied by a factor derived from the comparison of soda lime and LECO analysis values for 1881 and 1893 samples. Soda lime analysis by the method of Will and Varrentrapp (Watt, 1863). See Johnston (1969a, p 50) for more details.

1881-1944: Selected samples re-analysed in 2001-4 by combustion analysis, based on the Dumas method, using a LECO combustion system. Measured on air-dried, finely ground soil (to pass a 355 micron or 44 mesh sieve).

1966, 1987-8: Kjeldahl digest method for total N (Bremner, 1965). The digest was then analysed colorimetrically using a Technicon continuous flow analyser. Measured on air-dried soil, finely ground to pass a 0.5mm sieve.

1992 onwards: Combustion analysis, based on the Dumas method, using a LECO combustion system. Measured on air-dried, finely ground soil (to pass a 355 micron or 44 mesh sieve).

Soil % organic carbon (%SOC)

1865: Derived from original soda lime analysis for total N and C:N ratios for 1893 for organic carbon (Dyer, 1902).

1881-1944: Selected samples re-analysed in 2001-4 by combustion analysis, based on the Dumas method, using a LECO combustion system to measure total carbon. SOC determined as total C minus CaCO3-C, measured by a calcimeter (see below). Measured on air-dried, finely ground soil (to pass a 355 micron or 44 mesh sieve).

1966: Chromic acid titration method (Walkley and Black, 1934). Correction factor of W-B x 1.3 used, which is equivalent to organic C by Tinsley or total C by combustion minus CaCO3-C. But see also Johnston (1969b, p 97). Measured on air-dried soil, ground to pass a 0.5mm sieve.

1987-8: Dichromate digestion, modified Tinsley (Kalembasa and Jenkinson, 1973) to measure organic C. Measured on air-dried soil, finely ground to pass a 0.5mm sieve.

1992 onwards: Combustion analysis, based on the Dumas method, using a LECO combustion system to measure total C. Measured on air-dried, finely ground soil (to pass a 355 micron or 44 mesh sieve). SOC determined by subtraction of CaCO3-C, measured by a calcimeter (see below).

Inorganic carbon (IC) also known as calcium carbonate-C or CaCO3-C

Soils sampled in 1865-1936 were re-analysed in 2000-4. Most of the 1944 data was from the 1944 analysis, except for a few plots (9, 18 and 19) that were analysed in 2001. IC was not measured in 1987-88, as %SOC was determined directly by Tinsley analysis. In other years IC is subtracted from total carbon to give %SOC.

All samples up to 2012 were analysed by a calcimeter. CO2 is liberated from CaCO3 in the soil sample by treating with hydrochloric acid (HCl) in a closed system. The amount of CaCO3 is calculated by comparing the pressure produced by the sample against the pressure produced by known weights of CaCO3, using a mercury filled manometer. %CaCO3-C or %IC is derived from %CaCO3 by dividing by 8.333. Since 2014 inorganic C has been measured by an automated Skalar Primacs inorganic carbon analyser.

Soil pH

Soil pH in water, with a 1:2.5 soil:water suspension, mean of two readings. Soils from selected treatments sampled in 1865-1944 were re-analysed in 2000-4. Measured on air-dried soil, sieved < 2mm.

Olsen-P (plant-available phosphorus; also known as bicarbonate soluble-P or NaHCO3-soluble P)

Soils from selected treatments sampled in 1865-1944 were re-analysed in 2000-4. All samples were analysed by the Olsen method, in which soil is extracted with a solution of 0.5M NaHCO3, buffered at pH 8.5 (Olsen et al, 1954). The extract is then analysed by continuous segmented colorimetric flow analysis. Measured on air-dried soil, sieved < 2mm.

See Blake et al (2000, 2003) for a discussion of the P balance on Broadbalk and changes in soil P fractions over time (Key References, below).

Exchangeable cations - Calcium (Ca), magnesium (Mg), potassium (K) and sodium (Na)

Selected soils sampled in 1865-1944 were re-analysed in 2000-6, and those sampled in 1966 were re-analysed in 2019. All soils were extracted with 1M ammonium acetate (NH4CH3CO2) solution, after the method of Metson (1956). The data is expressed as mg kg-1 in dry matter, with 5mg of soil in 100ml of leachate. Since 1983, the extracts have been analysed by ICP-OES (Inductively Coupled Plasma - Optical Emission Spectrometer). Measured on air-dried soil, sieved < 2mm.

Blank (control) values: Analysis blanks were subtracted from exchangeable Na, and other cations if necessary (e.g. K in 1987).

Samples taken in 1966 were re-analysed in 2019. The exchangeable K values differ from those published by Johnson (1969b), when a slightly different technique was used for measuring exchangeable cations, which involved swirling the samples in successive amounts of ammonium acetate and decanting off the solution once settled. In 1966 the extracts were measured with a flame photometer. Bolton (1972) reports on exchangeable Ca and Mg in Broadbalk soils from 1856-1966 for some sections, from the western (top) end of the field, but the 1966 data has not been found. It is recommended that the re-analysed data from 2019 is used for the 1966 samples.

See Bolton (1972) for changes in exchangeable Ca and Mg, 1856-1966 and Blake et al (1999) for a study of soil K content, crop K uptake and K balance in Broadbalk (Key References, below).

Methods References:

  • Bremner, J. M. (1965). Total nitrogen. In: Methods of Soil Analysis. Part 2 (ed. C. A. Black), pp. 1149-1178. Madison: American Society of Agronomy
  • Johnston, A. E. (1969a) "The plant nutrients in crops grown on Broadbalk", Rothamsted Experimental Station Report for 1968, Part 2, 50-62 DOI:10.23637/ERADOC-1-34916
  • Johnston, A. E. (1969b) "The soils of Broadbalk: Plant nutrients in Broadbalk soils", Rothamsted Experimental Station Report for 1968, Part 2, 93-115 DOI:10.23637/ERADOC-1-34923
  • Kalembasa, S.J and Jenkinson, D.S (1973) A comparative study of titrimetric and gravimetric methods for the determination of organic carbon in soil. Journal of the Science of Food and Agriculture 24: 1085-1090.
  • Metson, A.J. (1956). Methods of chemical analysis for soil survey samples. New Zealand Soil Bureau, Bulletin 12.
  • Olsen S.R., Cole C.V., Watanabe F.S., Dean L.A. (1954) Estimation of available phosphorus in soils by extraction with sodium bicarbonate. USDA Circular 939, US Gov. Print. Office, Washington, D.C.
  • Walkley, A. and Black, I.A. (1934). An examination of the Degtjareff method for determining soil organic matter and a proposed modification of the chromic acid titration method. Soil Science 37: 29-38.
  • Watt, H. (1863) A dictionary of chemistry, vols. 1-4. London: Longman, Green, Longman, Roberts and Green.
  • Further information and acknowledgements

    See Goulding et al (2000) for measurements of nitrate leaching from the Broadbalk wheat experiment from 1990-1999 (Key References below).

    With thanks to Andy Macdonald, Paul Poulton and Steve Freeman for help with compiling the data and text.

    Key References

    2021

    • Suravi, K. N. , Attenborough, K. , Taherzadeh, S. , Macdonald, A. J. , Powlson, D. S. , Ashton, R. W. and Whalley, W. R.(2021) "The effect of organic carbon content on soil compression characteristics", Soil and tillage research, 209, 104975
      DOI: 10.1016/j.still.2021.104975
    • Thomas, C. L. , Hernandez-Allica, J. , Dunham, S. J. , Mcgrath, S. P. and Haefele, S. M.(2021) "A comparison of soil texture measurements using mid-infrared spectroscopy (MIRS) and laser diffraction analysis (LDA) in diverse soils", Scientific Reports, 11, 16
      DOI: 10.1038/s41598-020-79618-y

    2020

    • Jensen, J. L. , Schjonning, P. , Watts, C. W. , Christensen, B. T. , Obour, P. B. and Munkholm, L. J.(2020) "Soil degradation and recovery - Changes in organic matter fractions and structural stability", Geoderma, 364
      DOI: 10.1016/j.geoderma.2020.114181
    • Redmile-Gordon, M. , Gregory, A. S. , White, R. P. and Watts, C. W.(2020) "Soil organic carbon, extracellular polymeric substances (EPS), and soil structural stability as affected by previous and current land use", Geoderma, 363
      DOI: 10.1016/j.geoderma.2019.114143

    2012

    • Powlson, D. S. , Bhogal, A. , Chambers, B. J. , Coleman, K. , Macdonald, A. J. , Goulding, K. W. T. and Whitmore, A. P.(2012) "The potential to increase soil carbon stocks through reduced tillage or organic material additions in England and Wales: A case study.", Agriculture, Ecosystems and Environment, 146, 23-33
      DOI: 10.1016/j.agee.2011.10.004

    2010

    • Gregory, A. S. , Bird, N. R. A. , Whalley, W. R. , Matthews, G. P. and Young, I. M.(2010) "Deformation and Shrinkage Effects on the Soil Water Release Characteristic", Soil Science Society of America Journal, 74, 1104-1112
      DOI: 10.2136/sssaj2009.0278

    2009

    • Gregory, A. S. , Watts, C. W. , Griffiths, B. S. , Hallett, P. D. , Kuan, H. L. and Whitmore, A. P.(2009) "The effect of long-term soil management on the physical and biological resilience of a range of arable and grassland soils in England", Geoderma, 153, 172-185
      DOI: 10.1016/j.geoderma.2009.08.002

    2008

    • Jenkinson, D. S. , Poulton, P. R. and Bryant, C.(2008) "The turnover of organic carbon in subsoils. Part 1. Natural and bomb radiocarbon in soil profiles from the Rothamsted long-term field experiments", European Journal of Soil Science, 59, 391-399
      DOI: 10.1111/j.1365-2389.2008.01025.x

    2006

    • Watts, C. W. , Clark, L. J. , Poulton, P. R. , Powlson, D. S. and Whitmore, A. P.(2006) "The role of clay, organic carbon and long-term management on mouldboard plough draught measured on the Broadbalk wheat experiment at Rothamsted", Soil Use and Management, 22, 334-341
      DOI: 10.1111/j.1475-2743.2006.00054.x

    2003

    • Blake, L. , Johnston, A. E. , Poulton, P. R. and Goulding, K. W. T.(2003) "Changes in soil phosphorus fractions following positive and negative phosphorus balances for long periods.", Plant & Soil, 254, 245-261
      DOI: 10.1023/A:1025544817872

    2000

    • Blake, L. , Mercik, S. , Koerschens, M. , Moskal, S. , Poulton, P. R. , Goulding, K. W. T. , Weigel, A. , Powlson, D. S. , Falloon, P. D. and Smith, P.(2000) "Phosphorus content in soil, uptake by plants and balance in three European long-term field experiments. Modelling refractory soil organic matter", Nutrient Cycling in Agroecosystems, 56, 263-275
      DOI: 10.1023/A:1009841603931
    • Goulding, K. W. T. , Poulton, P. R. , Webster, C. P. and Howe, M. T.(2000) "Nitrate leaching from the Broadbalk Wheat Experiment, Rothamsted, UK, as influenced by fertilizer and manure inputs and the weather", Soil Use and Management, 16, 244-250
      DOI: 10.1111/j.1475-2743.2000.tb00203.x

    1999

    • Blake, L. , Mercik, S. , Koerschens, M. , Goulding, K. W. T. , Stempen, S. , Weigel, A. , Poulton, P. R. and Powlson, D. S.(1999) "Potassium content in soil, uptake in plants and the potassium balance in three European long-term field experiments", Plant and Soil, 216, 1-14
      DOI: 10.1023/a:1004730023746

    1995

    1980

    • Avery, B. W.(1980) "Soil classification for England and Wales (higher categories). ", Technical Monograph 14, Soil Survey of England and Wales, Harpenden UK

    1972

    • Bolton, J.(1972) "Changes in magnesium and calcium in soils of the Broadbalk wheat experiment at Rothamsted from 1865 to 1966", Journal of Agricultural Science, 79, 217-223
      DOI: 10.1017/S0021859600032184

    1969

    • Avery, B. W. and Bullock, P.(1969) "The soils of Broadbalk: Morphology and classification of Broadbalk soils", Rothamsted Experimental Station Report for 1968
      Get from eRAdoc: ResReport1968p2-63-81
    • Johnston, A. E.(1969) "The soils of Broadbalk: Plant nutrients in Broadbalk soils", Rothamsted Experimental Station Report for 1968, Part 2
      Get from eRAdoc: ResReport1968p2-93-115
    • Salter, P. J. and Williams, J. B.(1969) "The moisture characteristics of some Rothamsted, Woburn and Saxmundham soils", Journal of Agricultural Science, 73, 155-156
      DOI: 10.1017/S0021859600024242

    1902

    Key References

    2021

    • Glendining, M. J. and Poulton, P. R.(2021) "Broadbalk Wheat Experiment plan and cropping 1852-1925", Electronic Rothamsted Archive, Rothamsted Research, Harpenden, Herts, AL5 2JQ, UK
      DOI: 10.23637/rbk1-sup-1534342858-02
    • Rothamsted_Research(2021) "Broadbalk Wheat Experiment plan and cropping 1926-1967", Electronic Rothamsted Archive, Rothamsted Research, Harpenden, Herts, AL5 2JQ, UK
      DOI: 10.23637/rbk1-plan1926-67-02
    • Rothamsted_Research(2021) "Broadbalk Wheat Experiment plan and cropping 1968-2017", Electronic Rothamsted Archive, Rothamsted Research, Harpenden, Herts, AL5 2JQ, UK
      DOI: 10.23637/rbk1-plan1968-2017-01
    • Rothamsted_Research(2021) "Broadbalk Wheat Experiment plan and cropping since 2018", Electronic Rothamsted Archive, Rothamsted Research, Harpenden, Herts, AL5 2JQ, UK
      DOI: 10.23637/rbk1-today2018-02
    • Addy, J. W. G. , Ellis, R. H. , Macdonald, A. J. , Semenov, M. A. and Mead, A.(2021) "The impact of weather and increased atmospheric CO2 from 1892 to 2016 on simulated yields of UK wheat", J. R. Soc. Interface, 18, 20210250
      DOI: 10.1098/rsif.2021.0250
    • Rothamsted_Research(2021) "Broadbalk Wheat Experiment cropping 1843-2021", Electronic Rothamsted Archive, Rothamsted Research, Harpenden, Herts, AL5 2JQ, UK
      DOI: 10.23637/rbk1-crop1843-2021-01

    2020

    • Addy, J. W. G. , Ellis, R. H. , Macdonald, A. J. , Semenov, M. A. and Mead, A.(2020) "Investigating the effects of inter-annual weather variation (1968-2016) on the functional response of cereal grain yield to applied nitrogen, using data from the Rothamsted Long-Term Experiments", Agricultural and Forest Meteorology, 284, 107898
      DOI: 10.1016/j.agrformet.2019.107898
    • Machtoldt, J. , Piepho , H.-P. , Honermeier, B. , Perryman, S. , Macdonald, A. and Poulton, P.(2020) "The effects of cropping sequence, fertilization and straw management on the yield stability of winter wheat (19862017) in the Broadbalk Wheat Experiment, Rothamsted, UK", The Journal of Agricultural Science, 158, 6579
      DOI: 10.1017/S0021859620000301

    2018

    • Johnston, A. E. and Poulton, P. R.(2018) "The importance of long-term experiments in agriculture: their management to ensure continued crop production and soil fertility; the Rothamsted experience. ", European Journal of Soil Science, 69, 113-125
      DOI: 10.1111/ejss.12521
    • Rothamsted_Research(2018) "Broadbalk experiment fertilizer and manure treatments, 1852-2021", Electronic Rothamsted Archive, Rothamsted Research, Harpenden, Herts, AL5 2JQ, UK
      DOI: 10.23637/rbk1-FertTreats
    • Rothamsted_Research(2018) "Broadbalk experiment plan revised 2018", Electronic Rothamsted Archive, Rothamsted Research, Harpenden, Herts, UK.
      DOI: 10.23637/rbk1-today2018-01

    2016

    • J. Storkey , A.J. Macdonald , J.R. Bell , I.M. Clark , A.S. Gregory , N.J. Hawkins , P.R. Hirsch , L.C. Todman and Whitmore, A. P.(2016) "The Unique Contribution of Rothamsted to Ecological Research at Large Temporal Scales.", Advances in Ecological Research (eds: A.J. Dumbrell , R.L. Kordas and G. Woodward - Academic Press), Vol 55, Chapter 1, pp. 3-42
      DOI: 10.1016/bs.aecr.2016.08.002

    2012

    • Powlson, D. S. , Bhogal, A. , Chambers, B. J. , Coleman, K. , Macdonald, A. J. , Goulding, K. W. T. and Whitmore, A. P.(2012) "The potential to increase soil carbon stocks through reduced tillage or organic material additions in England and Wales: A case study.", Agriculture, Ecosystems and Environment, 146, 23-33
      DOI: 10.1016/j.agee.2011.10.004

    2009

    • Johnston, A. E. , Poulton, P. R. and Coleman, K.(2009) "Soil organic matter: its importance in sustainable agriculture and carbon dioxide fluxes", Advances in Agronomy, 101, 1-57
      DOI: 10.1016/s0065-2113(08)00801-8
    • Rothamsted_Research(2009) "Broadbalk experiment plan 1996-2017", Electronic Rothamsted Archive, Rothamsted Research, Harpenden, Herts, AL5 2JQ UK
      DOI: 10.23637/rbk1-plan1996-2017-01

    2006

    1996

    • Poulton, P. R.(1996) "Broadbalk Wheat Experiment", Global Change and Terrestrial Ecosystems, Report No. 7, GCTE Task 3.3.1, Soil Organic Matter Network (SOMNET): 1996 Model and Experimental Metadata (Smith P. , Smith J.U. and Powlson D.S. (eds) - GCTE Focus 3 Office, Wallingford, UK), 69-72

    1993

    • Hart, P. B. S. , Powlson, D. S. , Poulton, P. R. , Johnston, A. E. and Jenkinson, D. S.(1993) "The availability of the nitrogen in the crop residues of winter wheat to subsequent crops", Journal of Agricultural Science, 121, 355-362
      DOI: 10.1017/S0021859600085555

    1990

    • Jenkinson, D. S.(1990) "The turnover of organic carbon and nitrogen in soil", Philosophical Transactions of the Royal Society of London, Series B, 329, 361-368
      DOI: 10.1098/rstb.1990.0177

    1983

    • Dyke, G. V. , George, B. J. , Johnston, A. E. , Poulton, P. R. and Todd, A. D.(1983) "The Broadbalk wheat experiment 1968-78: yields and plant nutrients in crops grown continuously and in rotation", Rothamsted Experimental Station Report for 1982, Part 2
      Get from eRAdoc: ResReport1982p2-5-44

    1969

    For further information and assistance, please contact the e-RA curators, Sarah Perryman and Margaret Glendining using the e-RA email address: era@rothamsted.ac.uk