i8 



decrease was obtained, without a consistent variation in the acidity of the sap. Rock 

 phosphate apparently is not taken into the plant as mono-calcium phosphate. 



Reaction of the soil to litmus paper was determined from time to time. 

 After the first applications of sodium phosphate the soil reacted alkaline 

 to litmus on the surface, with decreasing alkalinity or acidity as the. dis- 

 tance below the surface increased. On March 22, 19 15, Section 295 

 (to which applications of 1000 g. of sodium phosphate had been made) 

 was found to have an alkaline reaction to litmus paper when tested for 

 each inch of soil down to the bottom of the bench (5 inches). Two 

 shoots each from plant Number 4, badly injured, and plant Number 12, 

 apparently normal, were taken and the sap expressed without previous 

 freezing. The sap reacted acid to phenolphthalein in each case. 



The power of soils to absorb bases from salts is well known. ^ With 

 this in mind, a liter of solution of disodium phosphate was made up with 

 carbon dioxide-free water, and aliquot portions titrated with standard 

 sulfuric acid to a faint rose coloration, using phenolphthalein as the indi- 

 cator. Six carnation cuttings, rooted in water, were cleansed by repeated 

 washing with distilled water and floated on the surface of 500 cc. of the 

 solution by placing them in holes of a paraffined cork. They were placed 

 in the greenhouse for six days, covered with a large bell jar and shaded 

 during the daytime. The cuttings were taken out, the solution care- 

 fully rinsed off and after removal of the roots the remainder of the shoots 

 was frozen, the sap expressed, and i cc. portions titrated with standard 

 alkali, using phenolphthalein as the indicator. Comparison was made 

 with the acidity of the sap from cuttings taken from the cutting bench 

 and prepared as in the former case for sap expression. 



Strength of Solution 2 G. Na2HP04.i2H20 per Liter. 



Titration of 10 cc. portions Titration of plant sap. 



H2SO4 (0.01550 N). KOH (0.02130 N). 



(1). (2). (1) Check. (2) Treated. 



0.32 cc. 0.31 CC. 0.92 cc. 1.3 1 CC. 



0.0048 CC. A' alkali per cc. 



In the absence of soil, the sap had become more acid when the plants 

 were grown in the disodium phosphate solution, hence the increased 

 acidity could not be attributed, at least entirely, to the absorptive power 

 of the soil for bases. 



Effect of Large Applications of Potassium Sulfate on Carbohydrate 

 Content of Sap and Foliage. — The increased exudation of nectar and 

 gluing together of the petals in the flowers on plants which had been treated 

 with large amounts of potassium sulfate has been listed among the charac- 

 teristic signs of overfeeding with this fertilizer (page 6). An attempt 

 was made to determine the cause of this increased flow. 



The amount of nectar present in an affected flower amounted to as much 

 as 1 cc. in the spring of 1912-13, when applications of potassium sulfate. 



