4 BULLETIN 47, U. S. DEPARTMENT OF AGRICULTURE. 



cial fertilizers. 1 from which there are important residual effects on 

 other crops in the rotation. The clean culture practiced also brings 

 all weeds into thorough subjection. The yields per acre of all farm 

 crops have been greatly increased since the extension of potato 

 growing. 



BY-PRODUCTS FOR FEEDING AND MANURE. 



That 40 per cent of the entire crop is fed to live stock has already 

 been pointed out. This is important for a diversified and profitable 

 s} 7 stem of farming, since it not only gives a large return in meat from 

 the 19,000.000 swine thus supported, but contributes an indispensable 

 supply of stable manure to the upbuilding of the soil. The nearly 

 100,000,000 bushels that are made into alcohol are mostly worked up 

 in farm distilleries, and the resulting by-product, or mash, possesses 

 considerable value for feeding cattle, and thus returns the greater 

 part of the fertilizing elements in the crop to the land. The more 

 than 50,000,000 bushels that are converted into starch, dextrin, and 

 related products enter quite largely into Germany's export trade. It 

 should also be mentioned that potato tops are now dried and used for 

 stock food on many estates. 



A MAXIMUM ACREAGE THE POLICY. 



For all these reasons the German farmers seek to plant a maximum 

 acreage of potatoes, and when, through the abundance of their har- 

 vests, their various markets are oversupplied there is not so much 

 talk of reducing production as of finding some new outlet for the 

 surplus. This is illustrated by the development of the potato-drying 

 industry. Previous to 1894 there had been an overproduction of 

 potatoes and low prices, to relieve which the Government united with 

 the organizations of the distillers and starch makers and with sev- 

 eral agricultural societies to offer prizes, aggregating 30,000 marks, 

 for the most practical and economical method of drying potatoes. 

 After thorough tests of the apparatus designed by the competitors 

 these prizes were awarded to several firms. That the method was 

 successful has been demonstrated by the rapid increase in the num- 

 ber of factories for drying potatoes, which now number 371. In 1910 

 more than 12,200,000 bushels of potatoes were dried in these factories. 



COMPARISON WITH AMERICAN CONDITIONS. 



SOIL FERTILITY. 



The disparity in the average yields of Germany and the United 

 States is not due so much to the superior quality of the German soils 



1 The average expenditure for potato manures on 140 German estates was $10.G8 pen- 

 acre, less than is frequently used in Maine or in the trucking districts of other States. 

 See Howard, W. II., Produktionskosten der wichtigsten Feldfriichte, Aufl. 3, Berlin, 1908. 



