296 Practical Farming 



way to the preservation of the mineral matters of their 

 soils by the use of the cheaper mixtures of phosphoric 

 acid and potash, and to a study of their soils to ascertain 

 whether they need to buy even both of these. 



Any farmer can ascertain approximately the needs of 

 his soil by laying out a series of plots, reserving one on 

 which no fertilizer is to be applied, then on another apply- 

 ing phosphoric acid alone, on another potash alone, on 

 another some form of nitrogen alone. Then on other 

 plots make combinations of nitrogen and potash, nitrogen 

 and phosphoric acid, potash and phosphoric acid, and 

 then a combination of all three. Then by noting the 

 results carefully for several seasons he can come very close 

 to what the land especially needs and what he need not 

 buy. We knew one wheat grower in Maryland who did 

 this, and years ago came to the conclusion that phosphoric 

 acid was the only thing needed on his land. He there- 

 fore adopted a short rotation of crops with clover on the 

 land frequently, and in a few years found that his wheat 

 crop increased from fifteen bushels per acre to an average 

 of forty bushels year after year, while he used only plain 

 dissolved South Carohna rock phosphate on his wheat, 

 and got through the clover all the nitrogen he needed. 



There are some crops hke the Irish potato which, when 

 grown as an early market crop demand special fertihza- 

 tion. Tobacco, too, is another crop on which we cannot 

 afford to omit a complete fertilizer. But for the ordinary 

 grain crops of the farm I feel sure that the man who farms 

 right, and works his land in a short rotation with legume 

 crops coming in frequently on the land, need never buy 

 an ounce of nitrogen in any form. 



