114 FERTILITY AND FERTILIZER HINTS 



to the soil and it should be preserved to prevent losses of the 

 essential elements by fermentation and leaching. The land 

 should be well drained and tilled. Crops should occupy the 

 land continually. Erosion must be prevented. Use commercial 

 fertilizers only to supplement the organic matter and those con- 

 stituents which should be contained in the soil. Fertilizers are 

 not expected to produce crops alone, unless increased amounts 

 are used every year. This is well illustrated by an experiment 

 conducted at the Louisiana Experiment Station on corn. For 

 four years commercial fertilizer only was applied to one plot 

 and legumes and farm manure was used on another plot. The 

 yield on the plot receiving commercial fertilizer alone, showed 

 12 bushels per acre and that on the plot receiving organic matter, 

 52 bushels, at the end of four years. 



Fertilizing Materials Used by Manufacturers. — The fertilizing 

 materials described in the previous chapters are those that the 

 manufacturers draw on for making their mixtures. The farmer 

 generally purchases his fertilizer in the mixed state under some 

 brand name, as Corn Fertilizer, B. C. Brand, etc., which does not 

 indicate the materials of which it is composed. The fertilizer 

 materials usually predominate in one constituent while the manu- 

 factured fertilizers show usually two or three of the constituents, 

 as nitrogen, phosphoric acid and potash. The manufacturers may 

 employ materials that furnish large amounts of a particular con- 

 stituent, as nitrate of soda, sulphate of ammonia, dried blood, 

 sulphate of potash, muriate of potash, kainit, and Tennessee or 

 Florida rock phosphate. He may choose some high grade 

 materials as those just mentioned and some low grade materials 

 as beet refuse, leather preparations, low grade cotton-seed meal, 

 soluble hair and wool waste, low grade bone-meal, etc. So when 

 a mixed fertilizer reaches the farmer the identity of the materials 

 of which it is composed is not known.* 



Basis of Purchase of Fertilizers. — There are two systems used 

 in purchasing fertilizers, namely, the unit system and the ton 

 system. 



I. The Unit System. — A unit is 20 pounds or one per cent, of a 

 ton. Manufacturers and dealers in fertilizer materials use the 



