MAINTAINING SOIL FERTILITY 299 



wheat, the last plowing is usually given before the 

 middle of August, so that the soil may have time to 

 settle and become compact before seeding. 



Oftentimes a short fallow may be practicable. 

 This consists simply in tilling the soil during the 

 few weeks that may elapse between the harvesting 

 of one crop, as barley, clover, or oats, and the sow- 

 ing of the next crop, as wheat. Occasionally land 

 is left idle for several weeks, or longer, when it 

 ought to be at work, either growing a green-manure 

 to plow under, or being subjected to the weathering 

 that is set in motion, by tillage. 



Summary oj Value of Fallowing. In American 

 farm practice, fallowing is used to advantage chiefly 

 for increasing the water content of soils, and for 

 cleansing them of weeds, rather than for increasing 

 their supply of available plant food and improving 

 their texture. It is often practicable in the dry 

 sections but rarely in the humid sections. It is not 

 adapted to leaohv soils. In this country fallowing 

 is practised chiefly in the arid and semi-arid 

 regions, under dry farming, and mostly in the 

 culture of wheat and oats. ^^ 



ROTATION OF CROPS 







Rotation of crops is the order or system in 

 which crops are grown upon the same land, and 

 refers to me sequence of crops when a number of 

 different kinds are grown, in distinction from the 

 one crop system. 



Very early in the history of agriculture it was 

 noticed that many crops grew much better if they 

 followed some other crops .than if grown con- 

 tinuously on the same land. Centuries ago En- 

 glish farmers divided their land into three parts, 



