WHAT WATER DOES IN SOILS 59 



countries of abundant rainfall. We thus see that, 

 also, more plant food remains in the arid soils than in 

 those of the region of summer rains, where the plant 

 food is washed into the streams and thence into the sea. 

 Therefore the soils of the arid regions, when irrigated, 

 nearly always give better crops than those of the humid 

 countries. They contain, for example, about ten times 

 more lime and three times more potash. Probably on 

 this account the arid countries have been most anciently 

 and continuously inhabited, as in the case of Egypt, 

 the Holy Land, Assyria, Babylonia, and northern India. 





