Boys' Second Book of Inventions

by Ray Stannard Baker

Having thus proved the remarkable efficacy of soil inoculation in his laboratory and greenhouses, where I saw great numbers of experiments still going forward, Professor Nobbe set himself to make his discoveries of practical value. He gave to his bacteria cultures the name "Nitragen"—spelled with an "a"—and he produced separate cultures for each of the important crops—peas, beans, vetch, lupin, and clover. In 1894 the first of these were placed on the market, and they have had a steadily increasing sale, although such a radical innovation as this, so far out of the ordinary run of agricultural operation, and so almost unbelievably wonderful, cannot be expected to spread very rapidly. The cultures are now manufactured at one of the great commercial chemical laboratories on the river Main. I saw some of them in Professor Nobbe's laboratory. They come in small glass bottles, each marked with the name of the crop for which it is especially adapted. The bottle is partly filled with the yellow gelatinous substance in which the bacteria grow. On the surface of this there is a mossy-like growth, resembling mould. This consists of innumerable millions of the little oblong bacteria. A bottle costs about fifty cents and contains enough bacteria for inoculating half an acre of land. It must be used within a certain number of weeks after it is obtained, while it is still fresh. The method of applying it is very simple. The contents of the bottle are diluted with warm water. Then the seeds of the beans, clover, or peas, which have previously been mixed with a little soil, are treated with this solution and thoroughly mixed with the soil. After that the mass is partially dried so that the seeds may be readily sown. The bacteria at once begin to propagate in the soil, which is their natural home, and by the time the beans or peas have put out roots they are present in vast numbers and ready to begin the active work of forming nodules. It is not known exactly how the bacteria absorb the free nitrogen from the air, but they do it successfully, and that is the main thing. Many German farmers have tried Nitragen. One, who was sceptical of its virtues, wrote to Professor Nobbe that he sowed the bacteria-inoculated seeds in the form of a huge letter N in the midst of his field, planting the rest in the ordinary way. Before a month had passed that N showed up green and big over all the field, the plants composing it being so much larger and healthier than those around it.

The United States Government has recently been experimenting along the same lines and has produced a new form of dry preparation of the bacteria in some cakes somewhat resembling a yeast-cake.

The possibilities of such a discovery as this seem almost limitless. Science predicts the exhaustion of nitrogen and consequent failure of the food supply, and science promptly finds a way of making plants draw nitrogen from the boundless supplies of the air. The time may come when every farmer will send for his bottles or cakes of bacteria culture every spring as regularly as he sends for his seed, and when the work of inoculating the soil will be a familiar agricultural process, with discussions in the farmers' papers as to whether two bottles or one is best for a field of sandy loam with a southern exposure. Stranger things have happened. But it must be remembered, also, that the work is in its infancy as yet, and that there are vast unexplored fields and innumerable possibilities yet to fathom.

Wonderful as this discovery is, and much as it promises in the future, its efficacy, as soon as it becomes generally known, is certain to be overestimated, as all new discoveries are. Professor Nobbe himself says that it has its own limited serviceability. It will produce a bounteous crop of beans in the pure sand of the sea-shore if (and this is an important if) that sand also contains enough of the mineral substances—phosphorus, potassium, and so on—and if it is kept properly watered. A man with a worn-out farm cannot go ahead blindly and inoculate his soil and expect certain results. He must know the exact disease from which his land is suffering before he applies the remedy. If it is deficient in the phosphates, bacteria cultures will not help it, whereas if it is deficient in nitrogen, bacteria are just what it needs. And so agricultural education must go hand in hand with the introduction of these future preservers of the human race. It is safe to say that by the time there is a serious failure of the earth's soil for lack of nitrogen, science, with this wonderful beginning, will have ready a new system of cultivation, which will gradually, easily, and perfectly take the place of the old.

Before leaving this wonderful subject of soil inoculation, a word about Professor Nobbe himself will surely be of interest. I visited his laboratory and saw his experiments.

Tharandt, in Saxony, where Professor Nobbe has carried on his investigations for over thirty years, is a little village set picturesquely among the Saxon hills, about half an hour's ride by railroad from the city of Dresden. Here is located the Forest Academy of the Kingdom, with which Professor Nobbe is prominently connected, and here also is the agricultural experiment station of which he is director. He has been for more than forty years the editor of one of the most important scientific publications in Germany; he is chairman of the Imperial Society of Agricultural Station Directors, and he has been the recipient of many honours.

We now come to a consideration of the other method—the fixing of nitrogen by machinery: a practical problem for the inventor.

Every one has noticed the peculiar fresh smell of the air which follows a thunderstorm; the same pungent odour appears in the vicinity of a frictional electric machine when in operation. This smell has been attributed to ozone, but it is now thought that it may be due to oxides of nitrogen; in other words, the electric discharges of lightning or of the frictional machine have burned the air—that is, combined the nitrogen and oxygen of the air, forming oxides of nitrogen.

Mr. Charles S. Bradley.