This section is from the book "The Potato: A Compilation of Information from Every Available Source", by Eugene H. Grubb, W. S. Guilford. Also available from Amazon: The Potato: A Compilation Of Information From Every Available Source.
As Will be seen by the graphic map of the world in Chapter I (Importance Of The Potato), the aggregate potato production of the countries on the continent of Europe is enormous.
During his European trip in the interest of American potato growers, the senior author spent considerable time in France and Germany and is indebted to Consul-General Frank M. Mason, Paris; Robert P. Skinner, Consul-General, Hamburg; Lutten & Son, commission merchants, Hamburg; and Baron Kriesheim of Bariskow, for many courtesies and kindnesses.
In a report of Consul-General Robert P. Skinner of Hamburg the following facts about the situation in Germany are given:
A number of causes have combined to bring about the immense German potato crop, which has apparently reached the limit of profitableness, as, in spite of the efforts of the German Government to encourage the industrial use of potatoes, only 4 per cent. of the total crop is taken up for the manufacture of starch and its by-products, and 8 per cent. for the distillation of alcohol. Thus the chief demand for potatoes remains the ordinary consuming market, which, because of climatic conditions, looks to a number of foreign countries for considerable quantities of early varieties. There are in this country immense areas of poor agricultural land which yield fairly well when planted with potatoes, and as the crop is valuable for rotation purposes, and the table demand probably greater, relatively, in Germany than in any other country, and the industrial applications numerous, the succeeding years have seen the yield advance steadily to an average which now exceeds 45,000,000 tons.
The cultivation of potatoes is indirectly encouraged by the German Government, which confers special privileges upon farm distilleries consuming the products of the land. Consul-General Thac-kara, in his able report of October 3, 1908, has furnished valuable figures in regard to the production of potatoes and their uses. In respect to the agricultural distilleries, the Imperial Government permits them to produce a certain amount of grain or potato alcohol, the amount depending upon the size and the location of the farms and the annual demand for the product, upon the payment of a revenue tax of marks 1.05 (25 cents) instead of the usual tax of marks 1.25 (29.75) cents per litre. Alcohol distilled in excess of the quantum is subject to the higher rate of tax, and denatured alcohol is not subject to any tax at all. The slops are used for feeding and the refuse is returned to the land.
At the present time over 200 varieties of potatoes are raised in this country, the most of which are used indifferently for all purposes. Naturally, such varieties as have a small content of water are best adapted for the production of alcohol. In some parts of Germany a mealy potato is popular, while in others the watery variety is preferred. The hard, mealy tubers are found to keep better through the winter than the others. A loose and not too heavy soil is preferably chosen for this culture, as in a heavy soil the crop is likely to deteriorate or become diseased. In the proximity of large cities farmers seek to raise favorite table varieties, and in the remote, and particularly the northern, portions of the country the crop goes to a large extent to the alcohol distilleries or starch factories, or to cattle feeding purposes. In portions of the empire where grain is a large crop potatoes are planted every fifth or sixth year. Cabbage also is raised for rotating purposes between wheat and rye, or other cereals. Should the demand for this vegetable be considerably increased there are large tracts of marsh and heath land in northern Germany which could be improved and made to yield potatoes in fair quantities.
The success of the German farmer with potatoes has largely resulted from the necessity of securing an income from soil which could hardly be utilized for anything else, and upon such soils, in addition to stable manure, large quantities of industrial fertilizers are also applied. In connection with experiments made by order of the Director of the Botanical Garden of Hamburg, the following industrial fertilizers have been successfully used for the cultivation of potatoes:
Kainit........... 0.7 tons per hectare (2.47 acres)
Thomas meal..... 0.5 " "
Chilean nitrate. . . 0.3 " "
The kainit and Thomas meal were applied in the fall and the nitrate was strewn in the spring. Instead of nitrate, sulphate of ammonia was also used. No mention is made of superphosphates as having been used in these experiments, although farmers employ them to a very large extent. Kainit is a mixture of sulphate of potash and sulphate of magnesia with variable proportions of chlorure of magnesium and marine salt. The useful substance in this combination is the potash which is represented by a proportion of 12.96 per 100. As the chlorure of magnesium is a salt destructive to vegetation, the use of raw kainit is not recommended. As a rule it is sold in prepared form after having been calcined, whereby the chlorure is eliminated.
Thomas meal is a fertilizer made from basic slag. Concerning Chilean nitrate of soda it is scarcely necessary to speak. In respect to this fertilizer, C. V. Garola says that it is not an indispensable fertilizer, and need not be employed unless it furnishes a pound of azote at a cost inferior to that of other fertilizers containing azote, such as blood, horns, flesh, and, particularly, sulphate of ammonia.
Mr. Garola, already quoted, in his Ten Years of Agricultural Experiments' says in regard to the effect of fertilizers upon the cultivation of potatoes: 'The potato is always very grateful for the manure that it receives. A strong manure, well prepared, is the first condition to a good crop. By using it to an extent of thirty tons (the author does not state over what area) I have obtained an increase of 88 per cent. in the yield; and a small dosing of manure, completed by super-phosphate and nitrate of soda, increased the crop by 105 per cent.