15 



aluminum salts do not form compounds analagous to those of 

 ferrous and ferric salts, but behave like salts of calcium and 

 magnesium. No data were given. 



Prianischnikoff 1 working on the relative values of mineral 

 phosphates, made sand culture experiments with cereals manured 

 with phosphorites. The phosphoric acid was only slightly avail- 

 able. Under the same conditions certain other plants such as 

 peas, lupines, buckwheat, and mustard seemed to be able to util- 

 ize the phosphoric acid. The "podzols" (soils containing a 

 large amount of fine siliceous and organic matter) were appar- 

 ently able to render phosphorites available for cereals and other 

 plants. The same was true of forest and peaty soils. Some of 

 the black soils, however, were without action on the phos- 

 phorites. 



The results of numerous experiments conducted by Ullmann 

 and Grimm 2 showed that for months after the application of 

 superphosphate, phosphoric acid soluble in water passed through 

 a depth of soil equal to ten inches. The authors found only a 

 portion of the magnesia, lime, and oxides of iron and aluminum, 

 available for retaining phosphoric acid. The mechanical fixa- 

 tion appeared to depend on the amount of fine sand present, 

 especially sand of the fineness of dust. 



A series of experiments, on the use of lime, extending over 

 several years, have recently been carried out at the Rhode Island 

 Experiment Station 3 . The practical results obtained in field 

 tests by the use of lime in conjunction with phosphates are of 

 particular interest, and apparently contradictory to a majority of 

 the writers on agricultural chemistry. Because of its peculiar 

 interest, the work is quoted here in some detail. Crops were 

 grown for four successive years, and the average yields on the 

 limed and the unlimed plots recorded. The results on the yields 

 of hay are given herewith as being typical of those obtained 

 with the crops grown. The figures represent pounds per acre. 



1 Ann. Agron., 1899, 25, 177. 



2 Chem. Ind., 1900, 23, 61. 



3 R. I. Agr. Expt. Sta. Bull., No. 58. 



