92 CROP GROWING AND- CROP FEEDING 



use tankage in the fall as a carrier of nitrogen to wheat.* * * * Our experi- 

 ments do not support the claim that the acidulation of tankage is necessary, 

 unless the tankage has been adulterated with leather scraps or similar 

 material; they rather show that it is a disadvantage. * * * The sulphuric 

 acid used in acidulation costs only about one-third as much per pound as the 

 fertilizer is sold for. In point of fact, the manufacturer can very well afford 

 to pay $6 to $8 per ton for sulphuric acid to be sold again at $20 to $30. * * 

 In the field experiments of this Station factory mixed fertilizers, made by 

 firms of high standing, produce no greater crops than home mixed fertilizers 

 of equivalent composition. The cost of the factory mixed fertilizers was 

 greater by 50 to 90 per cent, than that of the equivalent home mixtures. 

 Physical and chemical examination of the two forms of mixtures show that 

 the factory mixed fertilizer is not more homogenous in its character than that 

 mixed by the farmer. Fertilizer materials may be as perfectly mixed with a 

 shovel on a barn floor or in a large box as by the most elaborate mixing 

 machinery." 



HOW TO MIX FERTILIZER. 



There is a widely prevalent idea that the chemical constituents of a fer- 

 tilizer must have a "filler" mixed with them to make bulk. This notion has 

 arisen from the fact that fertilizer mixers commonly use worthless materials 

 for fillers in low grade goods, so as to be able to sell them at an apparently 

 low price, while still getting full prices for all that is of value in them. The 

 various fertilizing constituents are already combined in such a way that no 

 further filler is needed, and they only need to be mixed in the desired propor- 

 tions. This mixing we have shown can be as well done on a barn floor as by 

 the most elaborate machinery. 



Having determined from a formula the proportions in which the articles 

 are to be mixed, is is a simple matter to spread them out in layers on the barn 

 floor, and then having set up an ordinary sand screen to shovel the mass 

 through the screen repeatedly, beating up all the lumps, till a perfect mixture 

 is made. After the mass has been shovelled through the screen two or three 

 times it will be sufficiently mixed for all practical purposes. In fact, if we 

 could distribute the materials over the land in the exact proportions needed, 

 there would be no necessity for mixing them at all, but this would take a 

 great deal more labor than mixing and spreading at one going over the 

 ground. 



We give elsewhere a series of formulas adapted to various crops on dif- 

 erent soils. These are largely for complete fertilizer mixtures containing due 



