I02 FERTILITY AND FERTILIZER HINTS 



Potassium nitrate, or saltpeter, contains from 12 to 13 per 

 cent, of nitrogen and 40 to 45 per cent, of potash. It is an 

 excellent fertilizer but the market price prohibits its general use.* 



Anunonium nitrate is a rich nitrogenous salt but it is too ex- 

 pensive to employ for fertilizing purposes. 



Silicate of Potash. — Some minerals as feldspathic rock contain 

 considerable amounts (12 to 15 per cent, and more) of potash. 

 These potash feldspars have been ground to a powder and put 

 upon the market for fertilizer from time to time. Experiments 

 show this material to be of very low crop producing value.* 



Iron sulphate is produced quite extensively as a by-product in 

 the manufacture of steel. Although iron is necessary for plant 

 growth most plants do not use more than 15 pounds of iron oxide 

 per acre and average soils contain 15 tons of this material per 

 acre in the surface soil to a depth of 9 inches. So it is evident 

 that soils contain abundant amounts of iron for the needs of 

 plants. 



Common salt, or sodium chloride, has been used for many years 

 in some of the older countries as a fertilizer. In this country a 

 product called agricultural salt has been on the market, which is 

 mainly common salt. Most of our soils are rich enough in 

 sodium so that applications of common salt are not necessary. 

 This material does not furnish any nitrogen, phosphoric acid or 

 potash.* 



Powder waste is another product that is principally made up 

 of common salt. Some of this material may contain nitrates in 

 which case it is more valuable than common salt, although it 

 should not be considered unless it can be had for nothing, or 

 very cheap. It should be applied in small quantities because of 

 the deleterious action that large applications of sodium chloride 

 have on vegetation. 



Sulphates of Soda and Magnesia. — The use of either sulphate 

 of soda or magnesia is hardly to be considered on American soils 

 except when some special crop is grown that depletes the soil 

 of them, which is indeed very rarely. When fertilizers are Used 

 there is enough of these constituents supplied for the needs of 



