INFLUENCE OF MAN ON SOIL FERTILITY — JACKS 329 



country was based on wool, and the rise of the wool trade gave a great 

 impetus to the enclosure of common land which, after enclosure, 

 was almost invariably put into pasture for sheep. Grass is the best 

 soil improver known; indeed, it is noteworthy today that wherever 

 soil improvement is being planned, from the Poles to the Equator, 

 first reliance is placed on grass. At the time of the Tudor enclosures, 

 at the end of the exhaustive stage of soil evolution, it was pressure 

 from commercial interests, and against the will of the great majority 

 of farmers, that gave the soil its first dose of fertility-producing 

 medicine. Later, great improvements, which would have been im- 

 possible on unenclosed land, were effected in pastoral and arable 

 farming, mainly with capital earned in the towns. Investment in 

 soil fertility was profitable because the towns provided a market 

 for all that the soil could be made to produce. 



Large-scale investment in soil fertility of money earned in com- 

 merce and industry continued until about 90 years ago with immense 

 benefits to both farmers and land. Then the opening up of the 

 New World brought near disaster to British agriculture, and offered 

 greater attractions than did British land for the surplus wealth of 

 the towns. 



However, the subsequent neglect of British agriculture, which 

 lasted until 1940, had little effect on the inherent fertility of the soils 

 because so much land went back to grass, which gave the soil a rest. 

 If arable farming had been maintained at the 1870 level with insuffi- 

 cient capital investment, the loss of inherent soil fertility might have 

 had serious consequences in the two world wars. At the present time 

 the crying need of the soil is for capital which can only be provided 

 in sufficient quantity by the products of industry. It is becoming 

 evident that, in future, Britain will be unable to rely to the same 

 extent as formerly on buying unlimited food from abroad, so more 

 of the wealth of the towns may again be diverted into the soil. Al- 

 ready the state pours money into the land on a vast scale ; the level of 

 soil fertility — crop yields — would fall immediately if the state ceased 

 to do so. 



NORTH AMERICA 



In North America the soil is going through a similar sequence of 

 evolutionary stages under the influence of Man. Social development 

 has been telescoped into a much shorter space of time than was the 

 case in Europe. Most people would say that industrial progress has 

 advanced further in America than in Europe, but it is of very recent 

 date and the beneficent effects of American industrialism on the soil 

 are only now beginning to be discernible. 



At first there was a period of "shifting cultivation" as the frontier 

 was pushed westward. The land was skimmed of its fertility and then 



