716 SOILS: PBOPSHTIES AND MANAOJEMSJNT 



615. Soils associated with dry-farming. — Dry-farming 

 is often closely associated with irrigation, being practiced 

 on the heavier soils where the water-storage capacity is 

 large and where the practice of irrigation is most difScult. 

 Successful dry-farming requires an annual rainfall of at 

 least fifteen inches, and twenty inches is much, safer as a 

 basis for the practice. A general principle to be observed 

 in dry-farming is that the shorter the soil moisture supply, 

 the lighter should be the rate of seeding. Wheat, for 

 example, may be seeded at the rate of only twenty pounds 



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Fia. 82.— Areas of western Umted States where dry-land farming is or 



may be practiced. 



