I9O AGRICULTURAL ANALYSIS 



BASIC PHOSPHATIC SLAGS 



162. Uses of Basic Slag. The importance of basic Bessemer 

 slag, the residue of the process of manufacturing steel by the basic 

 process from ores rich in phosphorus, is every where acknowledged. 

 The use of this material in the United States has not been very ex- 

 tensive, chiefly for the reason that practically none of it is pro- 

 duced in this country, sted not being made from phosphatic 

 ores. It is, however, made in very large quantities in Europe, 

 and it is stated that over 2,000,000 tons of it are used annually 

 in Germany alone for manurial purposes. 



Leavens has given the following reasons for believing that 

 basic slag is a superior quality of phosphatic fertilizer: 40 



I. The phosphoric acid in basic slag is in a form which can 

 not revert or go back to more insoluble forms when mixed with 

 the soil as is the tendency with all superphosphates. 



II. The phosphoric acid in basic slag is not washed from the 

 soil by the heavy rains and leached away in the drainage waters 

 as is the case with many other phosphates. 



III. Since the phosphoric acid in basic slag never wastes after 

 application to the soil, it follows that basic slag may be applied 

 at any time, either fall, spring, summer, or even in winter without 

 danger of loss. 



IV. In addition to its high content of phosphoric acid, the 

 large amount of lime in basic slag greatly adds to its value. In- 

 stead of having a souring effect upon the land, as do superphos- 

 phates, basic slag on account of its strong alkaline reaction sweet- 

 ens acid soils and restores them to a productive condition. 



The lime also possesses the valuable property of making avail- 

 able the potash already in the soil and has a similar effect on- 

 crude forms of organic nitrogen. In addition to the chemical 

 effects already mentioned, lime greatly improves the physical 

 quality of the land, loosening up compact clay soils, thus mak- 

 ing them more permeable, and compacting light sandy soils ren- 

 dering them more retentive of moisture and plant food. 



V. Basic slag also contains a considerable amount of magnesia 

 which is extremely valuable in changing crude forms of plant 



40 Basic Slag and its Uses, 1906 : 5. 



