;]() Tub Bulletin. 



table 7. results on field b, buncombe farm, 190s and 1909. 



By a comparison of plats in table 7 it will be seen that on Porter's 

 loam, phosphoric acid is the only material giving a decided profit on 

 corn. Throughout this table the profit from commercial fertilizer 

 on Porter's loam is decidedly less than on Toxaway loam ; but in 

 both cases phosphoric acid was the only constituent which gave any 

 decided profit. 



PHOSPHORIC ACID. 



The results which are given in this bulletin show conclusively that 

 phosphoric acid is required by both the upland and valley soils of 

 the mountains. Wherever it has been applied the yields have been 

 increased. The chemical analyses show that the total supply in any 

 of the types which are farmed extensively is below that commonly 

 required for the production of maximum crops, and that 20 to 30 

 large gTain crops would require as much of this clement as is con- 

 tained in the surface 6§ inches of most of the types. 



There are several sources from which phosphoric acid is com- 

 monly obtained as a fertilizer. These are acid phosphate, bone 

 meal, basic slag, and ground phosphate rock or floats. Floats is the 

 name given to ground jdiosjihate rock ; acid phosphate is the same 



