48 SOUTHERN FIELD CROPS 



These figures indicate that the grain depletes the land of 

 considerable quantities of nitrogen and phosphoric acid, 

 while the straw removes a large quantity of potash and also 

 considerable nitrogen. The straw, after being used as 

 food or bedding, should be restored to the farm in the form 

 of manure. This, however, will usually not be applied to 

 the field from which the straw was taken. 



Phosphoric acid is very generally deficient in Southern 

 soils. Phosphate is the fertilizer usually applied to wheat. 

 Two hundred to four himdred pounds per acre may well 

 be employed. The time to apply acid phosphate to 

 wheat is at the time of sowing the grain. It may be sown 

 through the fertihzer attachment of the grain drill and 

 while the seed is being sown. The germination is not in- 

 jured by phosphate in contact with the seed. 



Since wheat makes most of its growth during the cooler 

 part of the year, while decay and nitrification are least ac- 

 tive, this plant responds profitably to applications of nitrog- 

 enous fertilizers. For the reason just indicated the most 

 readily soluble form of nitrogen, namely, nitrate of soda, 

 is usually the most effective form in which to convey at 

 least a part of the supply of nitrogen to the wheat plant 

 (Fig. 19). On account of its ready solubility, nitrate of 

 soda should not be applied until winter is past and the 

 plants have a well-developed root system ready to appropri- 

 ate the soluble nitrates. It is well to apply nitrate of soda 

 at least two months before the date of anticipated harvest. 



This usually means that in the Gulf States nitrate of soda 

 should be used by or before the twentieth of March, or in higher 

 latitudes at proportionately later dates ; 80 pounds per acre is the 

 amount most generally advisable, — though profitable use can 



