§ CIRCULAR 436, U. S. DEPARTMENT OF AGRICULTURE 



of application. However, in the future, if agriculture becomes more 

 intensified in this country, and more attention is given to the indi- 

 vidual plant and soil type, there probably will be a more careful use 

 of sodium nitrate, especially in solution as now practiced by some 

 specialists. 



SPECIAL USES 



Sodium nitrate is often used in solution, especially among florists. 

 Diluted at the rate of 1 ounce to 2 gallons of water, it has been recom- 

 mended for the growing of flowers in greenhouses. It has also been 

 used in the irrigation water for growing truck crops, such as cucumbers. 

 Generally the nitrate is used most advantageously at a rate not 

 exceeding 50 pounds to each 7,000 or 8,000 gallons of irrigation water. 

 When dissolved in the irrigation water, sodium nitrate gives a very 

 quick response. 



SOIL BACTERIA 



The application of sodium nitrate under some conditions influences 

 the bacterial flora of the soil. This is partly due to the quickly 

 available plant food supplied and may also in part be influenced by 

 the change in the soil acidity. Where large amounts of organic 

 material, such as straw or similar products, are turned under, the 

 initial bad effect of this practice may be minimized by adding sodium 

 nitrate to the soil as a nutrient for the bacteria which are instrumental 

 in breaking down the straw. This gives a supply of quickly available 

 nitrogen for the bacteria which otherwise would compete with the 

 crop itself for available nitrogen in the soil. 



NITRATE IN MIXTURES 



When nitrogen is the limiting factor, as is the case on many soils, 

 an application of sodium nitrate, alone may give very profitable re- 

 turns, but with the increase in the amount of nitrogen it may be 

 necessary to add carriers of phosphoric acid and potash to balance 

 the nitrogen. In this way larger amounts of sodium nitrate may be 

 used successfully. Inasmuch as it is difficult to distribute evenly 

 small amounts of sodium nitrate, if phosphate is also needed, it is 

 often advisable to mix the sodium nitrate with superphosphate. 

 This will not only insure more even distribution of sodium nitrate 

 but add phosphoric acid in quickly available form. This applies 

 also to potash where needed. 



COMPLETE FERTILIZERS 



Sodium nitrate is a satisfactory material for use in complete mixed 

 fertilizers, and it has been widely used for this purpose in commercial 

 fertilizer mixtures. However, due in large measure to its higher price 

 per unit than competing products, there is a tendency to substitute 

 for it other fertilizer materials which may be obtained at lower prices. 

 Since the fertilizer-control laws of many States do not compel either 

 the use of sodium nitrate in fertilizers or a statement of the nitrogen 

 in nitrate form in fertilizers, the farmer or gardner must either apply 

 it as a top dressing, or home-mix his fertilizer, if he desires to be certain 

 of setting sodium nitrate. 



HOME MIXING 



Home mixing of fertilizers enables the farmer to make certain not 

 only that he is getting the actual materials he desires, but that he can 



