492 NATURE AND PROPERTIES OF SOILS 



3. Miscellaneous. 



fSandy soil 7-6-5 



a. Early potatoes * \ Loamy soil 5-8-5 



[Clayey soil 4-8-4 



fSandy soil 5-8-7 



b. Late potatoes * ] Loamy soil 4-8-6 



[Clayey soil 4-8-4 



c. General trucking * on sandy soils of Atlantic 



seaboard 5-8-7 



* Note. — Keduee ammonia if farm manure is used. 



In this table of suggested formulae, it is noticeable that 

 wherever manure is used, the ammonia is reduced or even 

 eliminated. Ammonia is also unnecessary on leguminous 

 crops. With vegetables, the ammonia is usually high. Top 

 dressings for pastures, meadows, and cereals in the spring 

 should always carry large quantities of readily available nitro- 

 gen. 



I n a mixed fertilizer, the phosphoric acid is generally h igh, 

 for reasons already explained. Due to the absorptive power 

 of a clay, the mixture applied to such a soil should generally 

 carry more phosphorus than that added to a sandy soil. Pot- 

 ash is usually lower in a fertilizer for clayey soils, due to the 

 possibility of liberating potassium from the soil itself by good 

 soil management. 



277. Amounts of fertilizers to apply. — The agricultural 

 value of a fertilizer is necessarily a variable quantity, since, 

 in applying fertilizers, a material subject to change is placed 

 in contact with two wide variables, the soil and the crop. 

 Moreover, soil conditions are constantly changing, thus forc- 

 ing a modification of the fertilizer applied to the same soil 

 bearing the same crop at different times. The factors influ- 

 encing the efficiency of a fertilizer application may be listed 

 as follows: (1) seed, crop, and adaptation of crop, (2) weather 

 conditions, (3) physical condition of the soil, including drain- 



