Joseph Henry Gilbert was born at Hull on August 1, 1817. He was a son of the manse being the second son of the Rev. Joseph Gilbert, a Congregational Minister. His mother was one of the gifted daughters of the Rev. Isaac Taylor of Ongar, and a well-known writer of hymns and songs for children. Whilst at school young Gilbert had the misfortune to meet with a gunshot accident which deprived him of the use of one eye, a mishap which for a time threatened to mar his future career, but his own inherent determination and the home-training of the manse enabled him to overcome the disadvantage of defective eye-sight, and triumph over physical disability.
From school he went to Glasgow University and studied chemistry under Professor Thomas Thomson, then to University College, London, where he attended the classes of Professor Graham and others, and worked in the laboratory of Professor Todd Thomson. Here it was, in Dr Thomson's laboratory, that he first met Mr J. B. Lawes, with whom he was afterwards so intimately associated. He then proceeded to Giessen for a short time, studying under Liebig and taking his degree of Doctor of Philosophy in 1840. Returning to London, he worked at University College, acting as laboratory assistant to Professor Thomson, and became a Fellow of the Chemical Society on May 18, 1841, when the Society was barely three months old. He then left London to take up calico printing and dyeing in the neighbourhood of Manchester, but returned south in 1843, at the invitation of Mr Lawes, to assist in the agricultural investigations at Rothamsted, Herts.
Mr John Lawes had begun experiments in 1837 on growing plants in pots with various manures. He discovered the fact that mineral phosphates when treated with sulphuric acid yielded a most effective manure. Taking out his patent for the production of superphosphates in 1842, Lawes soon found himself busy with the establishment of a successful business. Not wishing to give up the agricultural investigations which he had commenced in the fields of Rothamsted he decided to obtain scientific assistance, and remembering the young chemist he had met in Dr Thomson's laboratory, Gilbert was invited in June 1843 to superintend the Rothamsted experiments. Thus began that partnership in investigation which has yielded such a rich harvest of results, and an association with Rothamsted which lasted for fifty-eight years.
Gilbert was elected a Fellow of the Royal Society in 1860, and received a Royal Medal in 1867. He was President of the Chemical Section of the British Association in 1880, and President of the Chemical Society, 1882-3. In 1884 he was appointed Sibthorpian Professor of Rural Economy at Oxford, and held the chair until 1890. He was a member of various foreign academies and societies, and was the recipient of honorary degrees from several home universities, becoming LL.D. of Glasgow (1883), M.A. of Oxford (1884), LL.D. of Edinburgh (1890), and Sc.D. of Cambridge (1894). In 1893 on the occasion of the jubilee of the Rothamsted experiments he received the honour of knighthood.
The character and scope of Gilbert's life-work was well described by Prof. Dewar at a special meeting of the Chemical Society in 1898, when he said, "The work of Gilbert, as we know, was early differentiated into that most complex and mysterious study, the study of organic life. For the last fifty years he has devoted his attention to the physiology of plant life in every phase of its development. With a skill that has been unprecedented, he has recorded from year to year the variations in the growth of every kind of nutritious plant. He has examined into the meteorological conditions, the variations of climate, of soil, and of mineral agents, of drainage, and of every conceivable thing affecting the production and development of plant growth. These memoirs are admitted throughout the world to be unique in their importance. Wherever the chemist or the physiologist, the statistician or the economist has to deal with these problems, he must turn to the results of the Rothamsted experiments in order to understand the position of the science of our time. These results will be for ever memorable; they are unique and characteristic of the indomitable perseverance and energy of our venerated President, Sir Henry Gilbert."
The close association of Lawes and Gilbert in the Rothamsted experiments makes it almost impossible to separate the work of the two men. The majority of the 132 papers issued from Rothamsted between 1843 and 1901 appeared under the joint names of Lawes and Gilbert, and it would be as difficult as it is undesirable to attempt an analysis of this partnership. It was essentially a partnership devoid of any jealousy, and actuated by a feeling of mutual regard and esteem. There never was a question as to the "predominant partner." The two workers formed an unique combination, each supplying some deficiency in the other. Lawes possessed the originating mind and had a thorough knowledge of the facts and needs of practical agriculture; Gilbert was the exact scientist, the man of detail and method. Dr J. A. Voelcker, who speaks of Gilbert as his life-long friend and teacher, says, "The partnership and collaboration of 'Lawes and Gilbert' represented an excellent embodiment of the motto 'Practice with Science.' Lawes was essentially the practical agriculturist—quick to see and grasp what the farmer wanted, and to become the interpreter to him. He was the man to whom the practical farmer turned, the one to write a brisk article on some subject of agricultural practice or economy, to answer a practical question, or to solve some knotty problem. Lawes was the more versatile of the two, the more inclined to introduce changes in and modifications of the original plan; and he has been known to say, jokingly, that if he had been left to have his own way, he would have ploughed up many of his experimental plots before they had yielded the full results, which continuance on the old lines alone brought out. Gilbert, on the other hand, was possessed of indomitable perseverance, combined with extreme patience and careful watching of results. His was the power of forecasting, as it were, what might, in the end, lead to useful results. With the determination to carry out an experiment to the very close he united scrupulous accuracy and attention to detail. Gilbert, it may be said, was not so much the man for the farmer, but for the scientist, and he it was who gave scientific expression to the work at Rothamsted, and who established field experiments on a scientific basis in this country."
To describe in detail Gilbert's work it would be necessary to write an account of the Rothamsted experiments, a task beyond our present limits seeing that the collected reports occupy nine volumes.
The last published "Rothamsted Memoranda" gives a list of 132 papers. They are divided into two series, one relating to plants, the other to animals.
Series I. deals with "Reports of Field Experiments, Experiments on Vegetation, &c., published 1847-1900 inclusive," and contains 101 papers. These reports on plants are concerned chiefly with the results obtained by growing some of the most important crops of rotation separately, year after year, for many years in succession, on the same land without manure, with farm-yard manure, and with various chemical manures, the same description of manure being, as a rule, applied year after year on the same plot.
Amongst the numerous field experiments conducted on these lines one of the most interesting is the field known as Broadbalk field, in which wheat has been grown continuously for over 60 years. The results show that wheat can be grown for many years in succession on ordinary arable land if suitable manure be provided and the land be kept clean. Even without manure of any kind the average produce for 46 years—1852 to 1897—was nearly 13 bushels per acre, about the average yield per acre of the wheat lands of the world. On this field it was found that mineral manures alone gave very little increase, whilst nitrogenous manures alone gave a much greater increase than mineral manures alone, but the mixture of the two gave much more than either alone. It is estimated that the reduction in yield, due to exhaustion, of the unmanured plot over 40 years—1852 to 1891—was, provided it had been uniform throughout, equivalent to a decline of one-sixth of a bushel per acre. It is related that a visitor from America, when being shown over the Broadbalk field, said to Sir John Lawes, "Americans have learnt more from this field than from any other agricultural experiment in the world."