Dataset: Broadbalk Crop Nutrient Content, Wheat 1968-2017

Tweet this dataset

Summary

From 1968 Broadbalk was divided into 10 sections. Wheat grain and straw from selected sections and plots were collected each year and analysed for macronutrient content: Nitrogen (N) each year, phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg) and sodium (Na) all years except 1976-1985 and sulphur (S) from 1996. Data is presented as % nutrient in grain and straw and is the response to different fertiliser treatments and cropping. The sample preparation, digestion methods and analytical instruments changed with time, but results over time are generally comparable.

Text updated February 2025.

Methods

Sample preparation: Crops are oven-dried to 80 degrees C. Grain samples are ground to <0.5mm, originally with a TEMA DISC mill, and later in the 1990s with an Ultracentrifugal mill (Retsch). Straw samples are ground to <1-mm using a Christy and Norris 8 inch Hammer Mill.

Nitrogen (N)

• 1968-1995: extraction by Kjeldahl digest, the digest analysed colorimetrically using a Technicon segmented flow analyser. If nitrate-N was expected to be high in the sample, the salicylic acid modification was used (Bremner, 1965).
• 1996 onwards: nitrogen content is determined by combustion analyser, based on the Dumas method. Originally a Heraeus Combustion analyser, currently a LECO combustion system is used.

Phosphorus (P), Potassium (K), Calcium (Ca), Magnesium (Mg), Sodium (Na) and Sulphur (S)

• 1968-late 1980s: dry ashing, as described by Piper (1942) was used to produce an acid extract. The extracts were analysed for P colorimetrically on a Technicon Auto Analyser, or later equivalents (Alpkem continuous flow system / Skalar SanPlus segmented flow system), using the modified Murphy & Riley (1962) molybdenum blue method developed from Fogg & Wilkinson (1958). K, Ca, Mg and Na were determined using atomic absorption methods. A Pye Unicam SP90 and later Perkin Elmer 372 atomic absorption spectrophotometer (AAS) was used to analyse Ca, Mg and Na; K was analysed by an EEL flame photometer until 1973, K was then analysed with Ca, Mg and Na by the AAS. S was not routinely measured until 1996.
• Late 1980s onwards: open tube nitric-perchloric digestion (Zarcinas, et al, 1987) has been used to produce an acid extract. P, K, Ca, Mg and Na have been determined by ICP-OES (Inductively coupled plasma optical emission Spectrometer) since 1982, and S since 1996.

See Additional Information for references for analytical techniques. For further information about comparison of methods, refer to the e-RA curators.

Technical Information

Blank (control) values: Data for sodium is presented after the analysis blanks (controls) have been subtracted from the raw data. Sodium blank values tend to be relatively large, and can be greater than the raw data. If subtracting the blank resulted in a negative value, this is shown as zero. Thus the sodium data should be treated with some caution. Blank (control) readings for the other nutrients are very small, relative to the treatment values, and have not been subtracted.

Grain and straw samples were not taken from all Sections. Section 1 and the 1st wheat (Sections 2-5 and 7) were sampled every year, and some other sections in later years. Straw was not always available in the same years that grain was measured.

Related Documents

• Johnston (1969) The plant nutrients in crops grown on Broadbalk, pp 50-62. :
• Dyke et al. (1983) Broadbalk wheat experiment 1968-78: yields and plant nutrients in crops. . . :
• Thorne et al (1988) Variation between years in growth and nutrient uptake after anthesis. . . :

Related Datasets

• Broadbalk wheat grain micronutrients 1845-2005

Contributors

• Sarah Perryman: Data curator
• Margaret Glendining: Data curator
• Andrew Macdonald: Project manager
• Paul Poulton: Researcher
• Richard Ostler: Project leader
• Ruth Skilton: Data collector
• Nathalie Castells: Data manager
• Mark Durenkamp: Data collector
• Chloe Garwood: Data collector
• Wendy Wilmer: Data collector
• Chris MacKay: Data collector
• Steve Freeman: Data collector

Dataset Access and Conditions

Rights Holder

Rothamsted Research

License

This dataset is available under a Creative Commons Attribution Licence (4.0).

Cite this Dataset

YOU MUST CITE AS: Sarah Perryman, Wendy Wilmer (2021). Dataset: Broadbalk Crop Nutrient Content, Wheat 1968-2017 Electronic Rothamsted Archive, Rothamsted Research, Harpenden, UK https://doi.org/10.23637/rbk1-BKNUTRW-01

Please review our How to Credit Datasets guidance for more information.

Conditions of Use

Rothamsted relies on the integrity of users to ensure that datasets are used appropriately and Rothamsted Research receives suitable acknowledgment as being the originators of these data. Please review the Conditions of Use before downloading.