PRODUCTION AND AGRICULTURAL USE OF SODIUM NITRATE 7 



RESIDUAL EFFECT 



While its immediate availability and loss from leaching would 

 seem to imply that there would be little residual effect of this fertilizer 

 on the soil, as a matter of fact it so stimulates plant growth that the 

 increased plant residues thus given to the soil under some conditions 

 continues the effect of the nitrate to a certain degree for several years. 



AGRICULTURAL USES OF SODIUM NITRATE 



The principal ways of using sodium nitrate from a crop-production 

 and fertilizer standpoint are (1) direct application to the soil as side 

 dressing, (2) in commercial and home-mixed fertilizer preparations, 

 and (3) special uses, such as the growing of greenhouse crops. The 

 most extensive use, however, is with the first two, although the third 

 may be expected to assume greater importance in the future. 



APPLICATION TO SOIL 



The application of sodium nitrate to the soil must be considered 

 in the light of its properties. As it is very soluble, large amounts 

 should not be applied at one time as any excess not used by the 

 plants would be lost as a result of leaching. If a large amount of 

 nitrogen is to be used in this form, it should be applied in divided 

 applications at intervals sufficient to allow the plants to use up the 

 nitrate. Losses of this character are most likely to be felt in open 

 sandy soils. In making mixed commercial fertilizers, it is often felt 

 advisable to include sodium nitrate, for immediate availability; 

 ammonium sulphate or some similar material, for continuing the 

 action of the fertilizer ; and some form of organic nitrogen carrier, such 

 as fish scrap, cottonseed meal, or tankage, to still further forward 

 the crop. 



The quantity of sodium nitrate to be applied to crops varies with 

 so many conditions that it is difficult to make any general statement. 

 Considering its price as compared with that of the products grown, it 

 will normally pay to use only from 50 to 200 pounds an acre for 

 general farm crops, but for special crops it may be possible to use 

 larger amounts to advantage. The amount of sodium nitrate to use 

 depends not only on the type of soil and of crop grown, but also on 

 the previous history of the soil and the amount of manure or compost 

 that is available. 



Sodium nitrate is often applied in the early spring before nitri- 

 fication has taken place in the soil, because a light application at this 

 time will give the plant a start and later when the soil warms up the 

 nitrogen already in the soil tends to become available for the crop. 

 For example, in the southeastern part of the country, an application 

 ranging from 75 to 100 pounds an acre of sodium nitrate applied to 

 corn when it is a few inches high will give it a good start and more 

 than justify the cost of the fertilizer, but the same amount of nitrogen 

 applied later in the season may not be profitable. 



It must not be forgotten also that an excess of sodium nitrate 

 applied at the wrong time will often delay maturity of the crop, and 

 from the business point of view do more harm than good. Sodium 

 nitrate is considered one of the most efficient carriers of nitrogen, but 

 it must not be considered a general cure-all for bad soil conditions. 

 Care must be exercised both in the amounts applied and in the time 



