1905.] 



On the Retention of Bases by the Soil. 



25 



contained in cylinders of Jena glass holding about 3 litres ; it was found that 

 after growth had gone on for some time the solutions had gained in alkalinity 

 by an amount equivalent to the nitrogen taken up by the plant, less the 

 alkalinity of the plant ash. One example of these trials will suffice. 



A cabbage plant made 7"52o grammes dry matter containing 2'705 per cent, 

 of nitrogen = 0'2035 gramme nitrogen, equivalent to 0'01454 gramme 

 hydrogen. The ash of the plant had an alkalinity equivalent to 

 0'01082 gramme hydrogen. The culture solution gained alkalinity 

 = O00558 gramme hydrogen, which with the 0"01082 gramme alkalinity of 

 the ash makes O0164 gramme of alkaline hydrogen found in ash and solution, 

 to correspond with the 0'01454 gramme of acid hydrogen equivalent to the 

 nitrogen in the plant. 



In 1904 six cultures were started with wheat in similar jars on March 3, 

 and growth was continued without changing the solutions until June 11, 

 when the grain was fully formed. Three grains were sown in each jar and 

 growth was extremely vigorous, but was continued a little too long, for at the 

 close of the experiment no nitrate remained in the solution. For purposes of 

 analysis a mixture was made of ISTos. 1 and 2, and of 3 and 4, the remaining 

 two being kept in reserve. Table XIII shows the results obtained. 



In the initial solution there was a trifling excess of acid over base owing 

 to the presence of a little ferric chloride, of which the acid alone is brought 

 into the account. At the end it will be seen that there is an apparent gain 

 of nitrogen, due in the main to dust (the greater part being present in the 

 sediment which formed in each jar) and the seed (which contained 



Table XIII. — Wheat Grown in Water Culture. Composition of Plant and 



Solution after Growth. 



Original Solution. 





Quantities 

 taken. 



Equivalent to 

 hydrogen. 



K 2 



MgO 



CaO 



Total bases ... 

 P 2 5 (monobasic) 



so 3 



CI 



grammes. 

 4 -2190 

 -6018 

 2 -8000 



gramme. 

 -0898 

 -0301 

 0-1000 



1 -4000 



2 -0974 



1 -2080 



2 -1658 



-2199 



o-iooo 



-0295 

 -0302 

 0-0608 



Total acid 





-2205 



