Purchase of Fertilizers 171 



low-grade mixtures cannot be made from high-grade 

 materials without adding "make-weight." The advan- 

 tages of high-grade products are concentration and high 

 quality of plant-food. 



It will be observed that formula No. 1 contains nearly 

 twice as much plant-food as No. 2, or, in other words, it 

 will require about two tons of a fertilizer made according 

 to formula No. 2 to secure the same total amount of plant- 

 food as is contained in one ton of No. 1. Now, the mate- 

 rial in No. 2, other than the actual plant-food, is of no 

 direct fertilizing value, it is of no more value as a fer- 

 tilizer than the soil to which it is applied, but the actual 

 cost of the constituents is considerably increased, because 

 the expenses of handling, bagging and shipping are just 

 double what they would be for No. 1. 



Formula No. 3 illustrates a low-grade fertilizer in 

 the sense that it contains the poorer forms of the con- 

 stituents, and furnishes a comparatively small total 

 amount of plant-food. The nitrogen is all in the organic 

 form, and is derived from tankage, which, while not the 

 poorest, is poorer than other forms of organic nitrogen. 

 The phosphoric acid is also in organic combination, and, 

 while useful under many conditions, is less useful for cer- 

 tain other conditions than the soluble in Nos. 1 and 2. 

 The potash, while soluble, is derived from kainit, which, 

 because of its large content of chlorin, is regarded as less 

 desirable for certain crops than the more concentrated 

 materials, muriate, or the high-grade sulfate, which is 

 free from chlorids. It would require more than 2| tons 

 of a mixture made according to this formula to furnish 

 as much total plant-food as would be contained in a mix- 

 ture made according to formula No. 1, besides the dis- 

 advantage of the lower quality of the constituents. 



