Aug. 2S, 1916 Effect on Plant Growth of Sodium Salts 



859 



weight of a quantity of sodium carbonate is 63 per cent of the weight of the 

 sodium bicarbonate that could be formed from it. 



In the following tables and discussions the sum of the sodium carbonate 

 and 63 per cent of the sodium bicarbonate found in the soil solution have 

 been designated as "carbonate salts." 



EFFECT OF SODIUM CARBONATE ON WHEAT SEEDLINGS 



Experiment i . — The soil used in this experiment was obtained on the 

 farm of the Truckee-Carson Field Station. It would be classed as a fairly 

 productive sandy loam. It was analyzed for alkali salts and found to 

 contain but a small quantity. The samples were made up in triplicate 

 and sodium carbonate in solution was added to each set in the following 

 percentages to the dry weight of the soil: Series 1, no treatment; series 2, 

 0.05; 3,0.10; 4,0.15; 5,0.20; 6,0.25; 7.o-3o; 8,0.35; 9.0.40; 10,0.45; 

 11, 0.50; 12, 0.60. 



Wheat was planted on November 1, 191 3, and cut and weighed on 

 December 11. Because of the lateness of the season, the growth had been 

 very slow. After the wheat seedlings were removed, the soil from each 

 set of pots was composited for analysis. The analysis was made of the 

 solution secured by thorough digestion with an excess of water. The 

 condensed results of this experiment are given in Table I. 



Table I. — Results of experiment 1 (iqij), giving the quantity of sodium carbonate added 

 to the soil, the quantity finally recovered as carbonates, the number of plants, and the 

 combined weight produced in each case 



1 In excess of sodium bicarbonate present at beginning of experiment. 



This experiment showed that where more than 0.30 per cent of sodium 

 carbonate was added to the soil no plant growth was obtained ; therefore 

 the analyses of the higher percentages have not been included in Table I. 

 The addition of 0.15 per cent of the salt reduced the germination of the 

 seed, so that the full number of plants was not obtained and the total 

 green weight produced was 73 per cent below that of the check series. 



