Johann Friedrich Mayer (agriculturist)

Work

Mayer is considered the most influential agricultural reformers of the late 18th Century through his many writings, in which he promoted sustainable agricultural reforms such as the use of fertilizer, new crops, such as potatoes, new ways of crop rotation, sophisticated agricultural devices, and advanced management methods. He also advocated free property for peasants. In the 18th Century the pressure upon agriculture had increased to feed the steady growing population, and Mayer was one of the driving forces to make this happen.

Valuable fossil as a manure

The 1804 Repertory of arts, manufactures and agriculture Richard Weston reports that "New manure appearing as an uncommon phenomenon in the Annals of Agriculture, it cannot be an uninteresting matter to disperse the knowledge of its valuable qualities, and how it came to be known, especially as it is now making a rapid progress into every enlightened country where the farmers are not above being taught from the ingenuity, labour, and researches of others, and of all the modern improvements in agriculture no one appears to be of greater consequence..." The general description, Weston gave, started with:

Description of the best Sort, and Method of proving its Quality.

From the experiments made in America, it is found, that that which is produced near the surface of the ground has not the qualities necessary for vegetation in so powerful a manner as that which is dug deeper, on account of the sun, frosts, and atmosphere weakening its virtues, and that the lumps composed of flat shining specula are preferred to those which are formed of round particle* like sand; but that all kinds of gypsum, however different in exterior form or appearance, have a perfect resemblance in their chemical and essential qualities.
To try its quality, some should be pulverized very fine; then put dry into an iron pot placed on the fire, and if it be good it will soon boil, and great quantities of the fixed air will escape by ebullition.

Method of preparing it.

The usual method of preparing it is, by first stamping it in a stamping-mill, and then grinding it in a common grist-mill; but the finer it is ground it is so much the better, nor must it be calcined, and the fresher from the quarry the qualities will be the stronger.
If you have not a stamping-mill break it with a large hammer, and then sift or grind it.

The Marnier, Quantity, and Time of sowing it.

The method of putting it on the land is sowing it in the broad-cast manner, as you sow corn, and the only Care necessary is to make the distribution as equal as possible. A day inclining to rain is to be preferred for sowing it; but if the weather be very dry it ought to be moistened before it is sown, to prevent it from blowing away, and the distribution being unequal.
From a variety of experiments already made, from six to eight bushels to an acre seem to be the most approved quantity for grass or clover; but when only half of the quantity has been used, its effects have been very visible, and more productive by three tons to an acre than some of the same land left unplastered. One farmer mentions that he used nine bushels...

Weston further explains about experiments on various soils, its effects on grasslands, and a comparison between dung and plaster. He ends up describing the experiments with fossil as a manure has had on barley and clover, buckwheat, cabbages and turnips, clover alone, Indian corn, rye and wheat.

Weston explicitly mentioned, that "it is to the indefatigable researches of Mr. Mayer, a German clergyman, that we are indebted for this valuable fossil as a manure; but where his residence is I have not yet been able to discover, nor have seen any of his .writings concerning it. In the year 1768 he first discovered its virtues as a manure, and its reputation soon caused it to be tried in various parts of Germany. Thence its fame spread to Switzerland and France. Near to Paris are several hills of it, named Montmartre, whence the Americans transported it to their country, and its reputation soon spread it through that continent, even to Quebec. As a proof of which, I have taken an account of the following experiments, from a book printed in that city, in French and English, but first published in various periodical works in Philadelphia, Pennsylvania, &c.; and from these American publications it was introduced into England, after having made a circuit of nearly ten thousand miles."

Legacy

Johann Friedrich Mayer was the first to present to the public a series of experiments upon it the relation of gypsum to agriculture, and many chemists have followed him in the 19th century. Early 19th century however a great variety of opinion remained with regard to its mode of operation, for example:

• The French agronomist Victor Yvart (1763–1831) believed that the action of gypsum is exclusively the effect of the sulphuric acid, which enters into its composition; and founds this opinion upon the fact that the ashes of turf, which contain sulphate of iron and sulphate of alumina, have the same action upon vegetation as gypsum.
• The French agronomist Charles Philibert de Lasteyrie (1759–1849), observing that plants whose roots were nearest the surface of the soil were most acted upon by plaster, concludes that gypsum takes from the atmosphere the elements of vegetable life, and transmits them directly to plants.
• Louis Augustin Guillaume Bosc intimates that the septic quality of gypsum (which he takes for granted) best explains its action on vegetation; but this opinion is subverted by the experiments of Davy.
• Humphry Davy found that, of two parcels of minced veal, the one mixed with gypsum, the other left by itself, and both exposed to the action of the sun, the latter was the first to exhibit symptoms of putrefaction. Davy's own belief on this subject is, that it makes part of the food of vegetables, is received into the plant, and combined with it. Davy postulated the idea of atmospheric carbon, which was dismissed by Albrecht Daniel Thaer, who postulated instead his "humus theory."

After being applied with success by Mayer in the year 1763, Gypsum soon came into general use, not only in Germany, but in France, America, Switzerland, and other countries. Sutton Thomas Wood of Oxford (1807) acknowledged, that it was cheaper than dung composts, much more convenient for carriage, and may be attained, where dung cannot be had. Its value cannot easily be ascertained, as there are few soils that will not be benefited by its application. It renews and invigorates those lands which have been exhausted by neglect and improper management, and it wonderfully improves some stubborn clays.

Another lasting contribution was Mayer's farmhouse design, presented in his 1773 textbook on agriculture and husbandry. This design; known as the so-called "Pfarrer-Mayer-Häuser", became quite popular not only in the area of Hohenlohe, but in larger parts of Germany. The type of farms are still present visible in rural Germany, and are nowadays characterized as the typical Hohenlohe's farmhouse.

Mayer is considered among the most important agricultural reformer of the late 18th century. To socially improve the situation of the rural population, Mayer advised his readers not just about to changing agricultural methods, but he was strongly committed and an outspoken advocate for change in the agrarian structure. He called for the abolition of forced labor and inveighs against hunting and pasture justices of the lord. The range of subjects treated by him is great from topics classified under the purely agricultural engineering to cultivation, fertilization, harvesting, livestock, etc. But he, again and again, focussed his writings on social ethical and diaconal questions of his town, and openly criticized that rural life would be better served with dutiful authorities and philanthropic landowner.