86o 



Journal of Agricultural Research 



Vol. VI, No. 22 



Beyond this critical point the reduction of germination and growth was 

 rapid and consistent. 



The experiment also showed that the quantity of sodium carbonate 

 recoverable at the end of the experiment was much less than had been 

 added to the soil at the beginning. The quantity of sodium bicarbonate 

 had been increased in every case, but the total carbonate salts recovered 

 was much less than had been added. 



The apparent loss of the sodium carbonate added to the soil is shown 

 in the difference between the figures in columns 2 and 5 of the table. 

 The data of Table I are shown graphically in figure 1. 



30 

 25 

 20 

 /S 



l.<25" 



6 



/ 



2 3 



5 6 7 / 2 3 

 5E&/F5 A/UM0E&S 



f 



\ 

 se 



7 



Fig. i. — Diagram of the percentage of sodium carbonate added to the soil in experiment i (1913), with the 

 percentage of carbonate and bicarbonate recovered and the total green weight of wheat obtained. 

 The solid black line on the left at each series number indicates the percentage of sodium carbonate added 

 to the soil; the line at the right shows the percentage recovered at the end of the experiment. The solid 

 portion of the line shows the carbonate and the hatched portion the bicarbonate. The curve at the 

 right of the figure shows the relative growth oi the plants in each series of pots. 



Experiment 2. — The experiment was in most respects a repetition of 

 experiment 1. The soil used was also taken from the same farm and 

 was of the same physical character, but had been made more productive 

 by the use of farm manure on the field from which it was taken. A 

 preliminary analysis of this soil gave the following results: Sodium 

 carbonate, o; sodium bicarbonate, 0.091 per cent; sodium chlorid, 0.006 

 per cent; sodium sulphate, o. 



A triplicate series of sample pots were made up as before and sodium 

 carbonate in solution was added as shown in Table II. 



The wheat was planted in the pots on September 22, 1914, and cut 

 and weighed on October 5. It was noted that with the successive 

 increases in the percentage of carbonate added the time required for 

 germination was increased, the percentage of germination decreased, and 

 the amount of growth, both of leaves and roots, decreased. The results 

 of this experiment are summarized in Table II. 



