340 ILLINOIS STATE DAIRYMEN'S ASSOCIATION 



Illinois system of permanent fertility ground natural limestone 

 is applied where needed at the rate of about two tons per acre 

 every four years. 



Phosphorus can be purchased, delivered at the farmer's rail- 

 road station in Illinois, for about three cents a pound in the form 

 of fine-ground natural rock phosphate; for lo to 12 cents a 

 pound in steamed bone meal, and for 12 to 15 cents a vpound 'in 

 acid phosphate or in basic slag phosphate. 



Phosphorus can be used with profit in any of these forms^ 

 but the data thus far secured in comparative experiments indi- 

 cate that, with equal amounts of money invested, the natural 

 rock phosphate will give the greatest profit in rational permanent 

 systems. At least 1,000 pounds per acre every four years should 

 be applied, and for the first application even two or three tons 

 per acre is not too much phosphate for those who best under- 

 stand the need and value of phosphorus on normal Illinois land. 

 On soils deficient in decaying organic matter, we advise the use 

 of bone meal, slag phosphate or acid phosphate, rather than rock 

 phosphate. 



Rotation with such crops as corn, oats, and clover depletes 

 the soil of all important elements of fertility, and always results 

 ultimately in land ruin on normal soils, unless some system of 

 restoration is practiced. Clover takes large amounts of calcium 

 and phosphorus from the soil, and the roots and stubble of the 

 clover crop contain no more nitrogen than the clover itself will 

 take from soils of normal productive power. 



To increase or maintain the nitrogen and organic matter of 

 the soil is the greatest practical problem in American agriculture. 

 In an hour's time one can spread enough limestone or phosphate 

 on an acre of land to provide for large crops of wheat, corn, oats ^ 

 and clover for ten or twenty years, while to supply the nitrogen 

 for the same length of time would require from 20 to 40 tons of 

 clover, or from 80 to 160 tons of farm manure, to be added to 

 the same acre of land, even though one of the four crops har- 

 vested secures its nitrogen from the air. 



To provide nitrogen in the Illinois system of permanent ag- 

 riculture requires the use of common sense and positive knowl- 

 edge, the same as with limestone and phosphorus. 



