AGRICULTURAL CHEMISTRY AND RESEARCH ...

Journal of the University of Wales Agricultural Society, (1993), 73, 116-125.

AGRICULTURAL CHEMIS TRY AND RES EARCH INS TITUTIO NS : PAST, PRESENT AND PROSPECTIVE

Nigel Faithfull1

PAST Agricultural chemistry may be considered to have begun with Carl Wilhelm Scheele (1742-1786) the Swedish pharmacist who isolated citric acid from lemons and gooseberries, and malic acid from apples. In France, Nicolas Theodore de Saussure (1767-1845) studied CO2/O2 changes during plant respiration, and also the mineral composition of plant ash.

In Britain, Sir Humphrey Davy, then Professor of Chemistry at the Royal Institution, published in 1813 a series of lectures under the title, 'Elements of Agricultural Chemistry'. He collated the scattered publications of the previous two centuries and tested some statements with his own experiments. Davy systematised the analysis of plants into nineteen constituents, and attempted on one occasion to assess the feeding value of 97 different grasses grown by the Duke of Bedford at Woburn. The Bath and West Society, founded in 1777, established a Committee of Chemical

1

Dr. Nigel T. Faithfull graduated in Chemistry at UCW Aberystwyth in 1968, and obtained M.Sc. and Ph.D. (Wales) degrees on automation in agricultural chemical analysis. He is currently Senior Research Associate at the Agricultural Sciences Analytical Laboratory, Frongoch Field Station, Aberystwyth

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Agricultural Chemistry and Research Institutions

Rese ar ch in 1805, and set up a laboratory in a vault in Netting House. It was here that Davy's methods were used by Drs. Archer and Boyd to analyse farmers' samples.

FATHER OF AGRICULTURAL CHEMISTRY '...the great services he had rendered to agricultural science and

economics, by his zealous promotions of designs for placing the art of farming on a more scientific footing.' Thomas Hardy, The Mayor of Casterbridge, (1886)

The title 'Father of Agricultural Chemistry', however, is usually ascribed to Bar on Justus von Liebig (1803-1873). He was Professor of Chemistry at the University of Giessen and published in 1840 his 'Organic Chemistry in its Relation to Agriculture and Physiology'. His rese arch group impressed the government so much that they financed the first state agricultural rese ar ch sta tion at Mockern, Nr. Leipzig, in 1851-2. Twenty-five years later there were 74 such sta tions in Germany, 16 in Austria and 10 in Italy. In the United States the first was not established until 1875 at Middletown, Connecticut, and that was largely due to a student of Liebig's, Samuel W. Johnson.

The very first research station was founded by J.B.Boussingault in 1834 at Bechelbronn in Alsace, France. The oldest existing station, however, is that at Rothamsted, situated twenty-five miles north of London. It was founded privately in 1843 by Sir John Bennet Lawes. It remained the only B ritish research station until the Woburn Experiment Station was established in

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1876 by the Duke of Bedford and the Royal Agricultural Society. Woburn Experiment Station was subsequently handed over to Rothamsted in 1936. The Long Ashton Research Station was founded in 1902, having 27 per cent of its costs funded by the Board of Agriculture. Commenting on the early situation in Britain, James MacDonald, in his preface to The Rothamsted Experiments' said it is 'curious that while on the continent of Europe and in America there are many Agricultural Experiment Stations, Great Britain, which for centuries has led the van in agricultural progress, can claim to have had for any considerable period of time but one extensive centre of original research', i.e., Rothamsted.

EARLY CHEMICAL ANALYSIS AT ROTHAMSTED

Initial research at Rothamsted Experimental Station was squarely based on chemical analysis. Lawes himself had one of the best bedrooms in the mansion professionally converted into a laboratory to enable him to assay the active principles in poppies, hemlock and other narcotic plants he was cultivating. The laboratory was later transferred to an old barn. With the passage of time, Lawes' interest in pharmacy declined and he became more concerned with the question of why bone-fertiliser acted well on some soils and not on others. His experiments included adding sulphuric acid to the bones to form a superphosphate of lime, an idea first suggested by Escher in 1835.

This

cured the inertness of crushed bones when used on these

awkward soils and established a use for the vast quantities of mineral

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phosphates which the geologists were discovering in Europe. He patented the process in 1842 and the modern fertiliser industry was born.

In 1843, Lawes invited Dr. Joseph Henry Gilbert (1817-1901) to join him. Gilbert was an analytical chemist who had studied for a while under Liebig. He had the disposition of a martinet, was meticulously accurate, but was so reactionary he would never use metric units; instead he had his burettes specially calibrated in thousandth parts of a gallon! The validity of his results were unquestionable but he lacked originality, directing the same excruciatingly dull analytical procedures for fifty-eight years. He accordingly resented any other younger scientist working at the laboratory, and was furious when Lawes invited the young chemist Robert Warington (1838-1907) to join him in the study of carbon and nitrogen changes in soils using more sophisticated analytical methods than employed hitherto.

Warington also improved the analytical methods for determining chloride and nitrate in rain and drainage waters. It is remarkable that during the last few years interest has again been aroused in the anion content of 'acid-rain' and soil

leachates,

and

the

recent

technique

of

high-performance

ion

chromatography developed by Dionex enables the determination of several anions at sub-p.p.m. levels within a few minutes.

The Barn Laboratory was soon inadequate, and in 1855 was duly replaced by

a new edifice designed by Gilbert's brother Charles,

who was an

architect. Sir John Russell (Director of Rothamsted, 1913-1943) described it as a wretched piece of work; one wall fell down during building and the

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rest collapsed in 1912. It was an unfortunate example of the dangers of nepotism.

At Aberystwyth, the Welsh Plant Breeding Station (now the Institute for Grassland and Environmental Research) was founded in 1919 under the directorship of Sir Reginald George Stapledon (1882-1960). His interest in grassland stemmed from contact with Edward Kinch, Professor of Chemistry at the Royal Agricultural College, Cirencester. Kinch was repeating work similar to that carried out at Rothamsted and Stapledon was asked to undertake the botanical analysis of the herbage.

The W.P.B.S. was established as a research department of the University College of Wales, Aberystwyth, with which it continues to have close collaborative links. Thomas Wallace Fagan was then the Advisory Chemist and Head of the Department of Agricultural Chemistry at the University College. He was a true scholar - winning an exhibition to Caius College, Cambridge in 1895, where he took a first class in the Science Tripos in Chemistry. Fagan was a mercurial character - hopefully not all agricultural chemists are characterised by such tense personalities! - but also kind and modest. He successfully pursued research into the chemistry of grassland as well as maintaining an analytical service to farmers. In the mid-1930s, the latter involved processing up to 500 samples annually. Fagan also lectured and cooperated with the W.P.B.S. in the chemical analysis of the herbage and cereal varieties they produced. His own research led to his being the first in Britain to deal comprehensively with the chemical composition of herbage plants, especially the variations associated with

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stage of maturity, ratio of stem to leaf, frequency of cutting, manuring, environment and strain or species. The plant constituents he measured commonly included ether extractable material, crude protein, true protein, fibre, ash, soluble carbohydrates, silica, silica-free ash, phosphoric acid and lime. He was more concerned with the effect of manuring on the nutrient composition of the crop than on its yield. One outstanding effect Fagan demonstrated was that the application of nitrate of soda as a fertiliser to Italian Ryegrass could increase the true protein content of the leaf by 63 per cent and the crude protein by 49 per cent. This contrasted with Liebig's insistence, supported by Daubeny, Professor of Chemistry and later of Botany, at Oxford, that nitrogen was not a necessary fertiliser ingredient because plants obtained sufficient nitrogen from the atmosphere. This illustrates the importance of sustained research, not only in opening up new frontiers of knowledge, but also in refuting respectable but misconceived theories which may be held with disadvantageous consequences. This holds true even now when one is not so much concerned with maximising yield with large applications of mineral fertilisers, but reducing run-off and leaching of nitrates and using the nitrogen-fixation of legumes to greatest advantage in mixed swards.

Fagan

retired in 1939, and owing to financial stringencies, his Chair

remained vacant until 1954 when it was filled by R.O.Davies who had taken over from Fagan as Head of Department. Meanwhile, the Department's advisory function had passed after the war to the National Agricultural Advisory Service (now A.D.A.S.) at Trawscoed.

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When the W.P.B.S. moved to the Gogerddan mansion in 1953 it had its own Chemistry Department headed by Goronwy ap Griffith. He was succeeded in 1968 by D.I.H.Jones who has enthusiastically directed research into the nutritive and toxic properties of forages, and developed new and improved methods of their assessment. The W.P.B.S. is, of course, known mainly for its famed varieties, including S.23 Ryegrass, S.48 Timothy and varieties of cocksfoot, clovers and arable crops. Few would argue that chemical analysis of the nutritional components of such species has played a crucial role in the selection processes used in their breeding.

At the Long Ashton Research Station, trace element analysis enabled the diagnosis of whiptail in cauliflower by Hewitt and Jones in 1947. It was shown to result from a deficiency in molybdenum which is an essential constituent of nitrate reductase and in another Mo-dependent enzyme, xanthine dehydrogenase.

One famous discovery made at the Rothamsted Experimental Station should be mentioned. Experiments on the natural insecticide pyrethrum were begun by Dr. Charles Potter in 1935. In the late 1940's he recruited Michael Elliott to study the structure-activity relationships of the pyrethrins. In 1973 Elliott produced NRDC 161 (deltamethrin) which revolutionised insecticide chemistry, being light-stable yet biodegradable; this avoided the persistence of organochlorines like DDT. It was the tenacity and determination of Elliott and his team over a very long period of painstaking, and often unexciting work, that enabled their success.

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PRESENT Some recent examples of research will demonstrate the continuing importance of agricultural chemistry in scientific establishments.

NIR Spectroscopy Near infra-red reflectance spectroscopy (NIRS) was applied to the analysis of agricultural products by Karl Norris and coworkers in 1968 and has since gained widespread acceptance in the feedstuffs industry for the rapid analysis of e.g. moisture, protein, oil and fibre in grain. Methods have been developed at the National Institute of Agricultural Botany to predict DOMD digestibility in perennial ryegrass and other grass species, and C.W.Baker of the A.D.A.S. laboratories at Starcross is developing computerised statistical procedures to relate spectral output to parameters normally determined by chemical methods of analysis in silage. Only a few minutes is sufficient to measure several feed constituents in a sample. Research to obtain a greater understanding of the mathematical treatments used in the method and its relationship to variability within the corresponding chemical analyses is being carried out at the Department of Agricultural Sciences at the University of Wales, Aberystwyth, using data supplied by A.D.A.S. Starcross. Research into the analysis of fresh samples of herbage is being undertaken at I.G.E.R.

The A.F.R.C. Food Research Institute have developed NIR methods for the analysis

of protein, lipid and starch in pea-flour, and its use in on-line

process control in the food industry. The Scottish Institute of Agricultural

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Engineering has applied NIR to the automatic quality grading and disease characterisation of potato tubers .

Endosperm electrophoresis The Chemistry Department of the Plant Breeding Institute, Cambridge, has been using the electrophoretic band patterns of endosperm proteins to characterise cereal varieties, especially wheat and barley. As the proteins are genetically determined, these patterns are very useful to seed-testing and trading organisations for varietal identification, and for defining distinctive features and assessing genetic uniformity of a variety. Pattern variation can be exploited for genetic analysis, and for assessing the effect of particular proteins or groups of proteins on processing quality.

Ruminant digestion and nutrition The Rowett Rese ar ch Institute has been developing a method for the estimation of amino acids in protein hydrolysates of animal feed by high-resolution gas-liquid chromatography. Stand ar d amino acids yield quantitative results and attention is now being focussed on those parameters which influence quantitation in natural samples. The susceptibility to microbial digestion of the various ryegrass cell types, both within the rumen and by isolated rumen bacteria in vitro is also being investigated. The aim is to relate the susceptibility to microbial attack with chemical composition. Research at the Institute is supported by a Department of Chemical and Physical Analysis with an annual throughput of about 87,000 analyses, one third of which are for nitrogen content.

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Other sophisticated methods are currently being used such as inductively coupled plasma spectroscopy at the Scottish Agricultural College, Auchincruive, and nuclear magnetic resonance spectroscopy at I.G.E.R., plus others which have only become available during the last 25 years or so.

PROSPECTS

The foregoing illustrates how agricultural chemical analysis has been and remains the main foundation stone of agricultural research departments. Several establishments have been recently closed in the name of rationalisation. It is hoped that essential long-term patient research will not be sacrificed for short-term financial gains. Some rationalisation has probably been warranted, but it is to be regretted that staff with irreplacable experience have been lost in the process. Meanwhile, we look forward to the outcome of the exciting research that is currently in progress, especially the application of state-of-the-art technology in the form of computerised analytical instruments to agricultural chemical analysis.

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