growing in humid regions relate to the maintenance or 

 increase of the supply of plant food in the soil ; in north- 

 ern climates the chief consideration, at least in the grow- 

 ing of cereals, is to get them ripe before fall frost comes ; 

 but in dry areas cropping practices are primarily con- 

 cerned with making the best possible use of the moisture 

 that falls. 



The principles underlying crop production are the 

 same the world over, but the relative supply of plant 

 food, heat and moisture under different climatic and 

 soil conditions determines the relative importance of the 

 different farm practices that are commonly used in 

 growing crops. The supply of the factor that generally 

 limits the yield in any given region largely determines 

 the general trend of farm practice there, and, as in the 

 case of the semi-arid regions, sometimes gives to the 

 practices followed the name by which the system is com- 

 monly known. 



2. History of Dry Farming. Before the present dry 

 farming movement began, the Chinese on the dry lands 

 of Western China and the American Indians in the arid 

 States and in parts of Mexico are known to have grown 

 crops under very dry conditions. It is reported also 

 that crops were produced in the dry parts of northern 

 Africa without irrigation. The ancient civilization of 

 the Orient, the Euphrates Valley, Palestine and Egypt 

 developed in dry climates, but chiefly in areas where 

 irrigation was practised. It is probable that many of 

 the dry farming practices are very old, but such meth- 

 ods as may have been used in early days must have been 

 largely lost to Americans, most of whom came from 

 humid countries. 



The recent development in America does not appear 



