May, '14] GRANITIC SOIL POTASSIUM. 25 



rate of 40 lbs. per acre, phosphoric acid (P20r>) at the rate of 50 lbs. 

 per acre, and potash (K2O) at the rate of 120 lbs. per acre. These 

 amounts are not to be recommended in practice but, for the pur- 

 pose of determining effects, are very satisfactory. The fertili- 

 zers were applied as top dressing. Some of these plots have been 

 under observation for seven years. 



An examination of the soil from these plots in the laboratory 

 shows that some of the fertilizer constituents disappear very rapid- 

 ly after they are applied to the soil. It is not difficult to find 

 the nitrate and ammonium salts for some time after they have 

 been applied but for all practical purposes the potassium and 

 phosphoric acid change from soluble forms soon after the first 

 good rainfall and in an ordinary application cannot be found by 

 chemical methods now in use. This is in keeping with the re- 

 sults obtained in the experiments which have already been dis- 

 cussed and which show the chemical reaction which takes place 

 between soils and potassium salts. Like the sulfate and chlo- 

 ride, the nitrate radical remains soluble until it finall}- disappears 

 through leaching or decomposition. 



Data are tabulated in Table XIX which show the relative 

 amounts of inorganic water-soluble soil constituents in a series of 

 fertilized and unfertilized plots. The determinations were made 

 some time after the fertilizers were applied and after a good rain 

 had fallen. The data in Tables XIX and XX were obtained by 

 extracting 100 grams of soil with 500 cc. of water for three min- 

 utes. After filtering through a Chamberlain porcelain filter, 

 100 cc. of the filtrate were evaporated to dryness, the organic 

 matter driven off and the residue weighed. 



Averages show that the plots fertilized carry a little more inor- 

 ganic water soluble material than those which have not been 

 fertilized. The relative amounts of soil and fertilizing elements 

 are so different that no very satisfactory results can be had to 

 determine the effect of the fertilizers on the soil constituents. 

 Clay soils very readily take up practicall}^ all of the soluble ferti- 

 lizer elements soon after they are api)lied. 



The water-soluble inorganic matter from a series of plots on a 

 light soil show the effect of the application of fertilizers. These 

 plots are in an orchard and have been fertilized for seven years. 



