AGRICULTURAL MACHINERY 166 



science of animal husbandry and of technical equipment, there 

 exists a certain optimum density of population, varying with the 

 geographical and economic conditions of each region, in order to 

 secure the maximum surplus production of animal foodstuffs. 1 

 When that optimum is passed, as seems to be now the case in the 

 United States, the increased population begins to trench upon the 

 surplus. On the other hand, below the optimum, each increase 

 in the population leads to a greater proportionate increase in the 

 product, and hence also in the exportable surplus, since when the 

 population is very small and the animal industries of the country 

 quite undeveloped, the surplus is nil. Various factors complicate 

 the determination of this optimum for new countries, notably the 

 proportion of waste land, the suitability of the whole country for 

 animal rearing, and the extent to which competitive cereal and 

 fibre crops are grown for export in excess of home requirements. 

 The great animal-raising regions of the world (exclusive of the 

 tropical highlands, as yet scarcely developed) lie between 30 and 

 60 from the Equator. Medium land under average climatic 

 conditions in these belts will maintain one head of cattle to about 

 3 acres or 1J to 2 sheep per acre all the year round, provided hay 

 arid some fodder crops are grown for winter use. 2 The optimum 

 density of population for the maximum surplus of animal food- 

 stuffs under existing conditions seems to be between 10 and 20 

 persons per square mile. Wherever such conditions as a high 



1 Cf. Max Sering, Landwirtschaftliche Konkurrenz Nordamerikas, 1887, 

 p. 609 : " ... the number of cattle per square kilometre rises to a certain 

 limit with the increasing density of the population ... it grows with the 

 number of the producers and the more complete methods of exploitation till 

 the time when all the suitable land is occupied and brought into use. Con- 

 versely the production of cattle per head of the population will be greatest 

 when the process of settlement is in its earlier stages . . . the number of 

 cattle per capita will gradually decline after a certain point, because . . . 

 the pasture lands available for the herds will be reduced in area by crop 

 cultivation." 



This, however, does not allow for the increases in the numbers of live-stock 

 due to the introduction of modern intensive methods as they exist in the 

 elaborating-commercial countries. 



On the plains of both North and South America the trend of development 

 seems to be from ranching pure and simple to cereal cultivation, and thence 

 to mixed farming. The curve of the number of live-stock per square mile 

 shows a downward movement from the first stage to the second, followed 

 by an upward movement in the third stage. The per capita curve may or 

 may not show an upward movement in this last stage. 



a The carrying capacity of English grazing land is said to be one bullock 

 for every 3 acres on an average the whole year round. C. Middleton ,in 

 evidence before a Royal Commission (Cd. 2644), QQ. 8157-9. 



1 The Argentine alfalfa pastures will carry one steer to 2 J acres in general 

 and one to 3J acres for fattening. U.S. Dept. Agric. Year Book, 1913, p. 357. 

 The distant natural pastures in Argentina carry one head of cattle to 6 acres 

 or one head of sheep per acre. U.S. Dept. Agric., Bureau of Animal Industry' 

 Bulletin 48, p. 55. 



The average carrying capacity of New Zealand land is one head of cattle 

 to 2 acres with fodder crops. Dominions Commission (Cd. 7170) Q. 2686. 

 The permanent pastures in the same country are expected to carry 1 to 3 

 sheep per acre. U.S. Daily Commerce Reports, Aug. 14th, 1911, p. 69. 



