CITRIC-SOLUBLE PHOSPHORIC ACID AND POTASH. 9 



In the case where large samples (25 grams) of slag and feldspar 

 were used the resulting solutions differed but little in respect to their 

 potash content, but considering the fact that the sample of slag con- 

 tained less than one-half as much potash as the feldspar, the per- 

 centage of potash dissolved from the former was nearly four times 

 as great. Moreover, while no quantitative determinations were made 

 of the total solids in solution, the amount dissolved from the slag 

 was apparently many times greater than that dissolved from the 

 feldspar. 



In the case where only 0.25 gram samples of the two substances 

 were used the slag jdelded a solution nearly three times as strong 

 (in respect to potash) as the feldspar, and when the quantity of 

 potash in the two substances is considered the percentage dissolved 

 from the slag was nearly seven times greater. 



RESULTS OF POT TESTS WITH SLAG FERTILIZER. 



Although the solubility of the potash and phosphoric acid in the 

 slag product was indicative of its agricultural value it was thought 

 advisable to test its merits by actually growing plants in soils treated 

 with this material, and comparing their growth with that of plants 

 grown under similar conditions in the same soils untreated and 

 treated with well-known potassic and phosphatic fertilizers. 



The experiments were conducted by Mr. J. J. Skinner of this 

 bureau. The wire-basket method described in Circular 18, Bureau 

 of Soils, was employed, using wheat seedlings. 



Three types of soil were used, namely, the Carrington silt loam 

 from Wisconsin, the Hagerstown loam from Pennsylvania, and the 

 Volusia silt loam from New York. These soils are described in 

 Bulletin 96 of this bureau as follows: 



The Carrington silt loam consists of a dark-brown to black silt loam, having 

 an average depth of about 12 inches. The subsoil is a yellowish-brown to pale- 

 yellow silty clay loam or silty clay. The topography is mainly level to undu- 

 lating. The soil represents a residual stratum derived from glacial till. The 

 type is admirably adapted to the general farm crops, including wheat, corn, 

 oats, barley, rye, flax, and grass. 



The Hagerstown loam is a brown or yellow loam averaging about 12 inches 

 in depth. The subsoil is a yellow or reddish clay loam to a depth of 24 inches, 

 but frequently grades into a stiff, yellowish-red clay. The type occupies rolling 

 valley land, and is derived from the weathering of pure limestone. This is 

 typical corn soil. It is one of tbe best general farming types in the eastern 

 States, and is used for corn, tobacco, wheat, grass, and apples. 



The soil of the Volusia silt loam, to an average depth of 8 inches, is a gray to 

 brown silt loam. The subsoil to a depth of 2 feet is a light-yellow silt loam, at 

 which point mottlings of gray or drab are encountered. Both soil and subsoil 



