Part of experiment rhb2

Hoosfield Crop Nutrient Content

The Hoosfield experiment was started in 1852 to investigate the relative importance of the plant nutrients nitrogen, phosphorus, potassium, magnesium and sodium (N, P, K, Mg and Na) and silicate (Si), applied as either fertilizer or manures, on the yield of spring barley. From the start of the experiment, samples of barley grain and straw were kept for chemical analysis, although straw samples from the 19th Century are limited.

Early analysis

Lawes and Gilbert (1857) reported on yield and %N for the first six years of the experiment, and Gilbert (1893) on yield and grain composition for the first 30 years.

Hall and Morrison (1906) and Fisher (1929) reported on the effects of silica on yield.

Russell and Watson (1939) comprehensively discuss the effects of the different plant nutrients and FYM on composition and quality of barley grain from 1852-1937. Yates and Watson (1939) also published data on crop N content.

Warren and Johnston (1967) compared N, P, K, Ca, Mg and Na content in grain and straw of the old variety Plumage Archer and the modern variety Maris Badger, in 1964 and 1966. This data is available in the dataset HFBNUTRI. They also report on the effects of sodium silicate on P%.

The whole experiment was fallowed in 1912, 1933, 1943 and 1967.

1968 to present

In 1968 some of the Hoosfield plots (subsequently called the "Main" plots) were divided into four sub-plots, to test four rates of N. Two three-course rotations with barley, potatoes and beans were started on Series AA and C of the experiment; plots were divided into 16 sub-sub-plots to accommodate the different crops and four rates of N. The rotations continued until 1978.

No barley grain or straw was analysed for nutrient content in 1968 or 1969. From 1970 onwards grain samples were analysed for total N every year. On the Main plots straw was also analysed, and in most years, P, K, Ca, Mg, Na were also determined. Sulphur (S) concentrations in grain and straw have been determined since 1996. See Main Plot nutrient data, 1964-2000 and Main Plot nutrient data, 2001 onwards for details of which elements were measured on which plots.

Leigh and Johnston (1983, 1985 and 1986) published a series of papers looking at N, P and K in dry matter and tissue water on the Hoosfield barley crops.

15N-labelled fertilizer was applied to plots of contrasting nutrient status on Hoosfield in 1986 and 1987. The grain and straw total N and 15N content was measured over several years (Glendining et al, 1997, 2001).

Hoosfield crop nutrient data is available from e-RA as the following datasets:

• HFBNUTRI: Spring barley grain and straw nutrient data, 1964 & 1966, two contrasting varieties, all plots
• HFNUTRIMAIN: Spring barley grain and straw nutrient data, 1970 onwards.
Main Plots 111-724 (old Series O and A) 1970-2000. Plots 631-4 and 731-4 were added 2001 onwards.

See Main Plot nutrient data, 1964-2000 and Main Plot nutrient data, 2001 onwards for details of which elements were measured on which plots.

Methodology

For analytical techniques used prior to 1968 see Johnston (1969) in Methodology References below.

Nitrogen (N)

1968-1995: nitrogen content was determined by Kjeldahl digest, the digest was then 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 techniques, as described by Piper (1942) were 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 automated atomic absorption methods. The SP90 atomic absorption flame photometer was used to analyse Ca, Mg and Na; K was analysed by the EEL flame photometer until 1973, K was then analysed with Ca, Mg and Na by the SP90. S was not routinely measured until 1996.

1980s onwards: since the late 1980s the 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.

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 sample values, and have not been subtracted.

Methodology 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.
• Fogg, D.N. and Wilkinson, N.T. (1958). The colorimetric determination of phosphorus. Analyst, London, 83:406-414.
• Johnston, A. E. (1969) "The plant nutrients in crops grown on Broadbalk", Rothamsted Experimental Station Report for 1968, Part 2, 50-62.
• Piper, C.S. (1942) Soil and plant analysis. The University of Adelaide, Adelaide, Australia.
• Zarcinas, B.A., Cartwright, B., Spouncer, L.R., 1987. Nitric acid digestion and multi-element analysis of plant material by inductively coupled plasma spectrometry. Communications in Soil Science and Plant Analysis 18:131-146.

Key References