862 



Journal of Agricultural Research 



Vol. VI, No. 22 



The difference in the effect of the carbonate in the two soils was 

 evident in a very few days. The time required for the wheat to emerge 

 was approximately the same in both cases, but in the sand all germination 

 was stopped by the addition of 0.20 per cent of sodium carbonate, whereas 

 it required the addition of 0.50 per cent to the loam to have the same 

 effect. The carbonate had a very detrimental effect on the physical 

 condition of the loam soil, causing a stiff crust to form on the top of the 

 pots, the crust becoming more noticeable with the increase of the per- 

 centage of carbonate. This made it difficult for the plants to break 

 through. The detailed results of the experiment with loam and sand 

 soils are given in Table III. 



6 7 a & 



Fig. 2. — Diagram of the percentage of sodium carbonate added to the soil in experiment 2 (1914), with the 

 percentage of carbonate and bicarbonate recovered and the 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 of the plants in each series of pots. 



A comparison of the data on loam and Monterey sand (Table III) 

 shows that the decrease in the yield of the plants was much more rapid 

 in the sand than in the loam. The apparent loss of carbonates was 

 much greater in the loam than in the sand. The loam soil also showed 

 a steady increase in the amount of recoverable sodium bicarbonate, 

 which was not the case with the sand. 



A marked difference is to be noted in the green weight of the plants 

 grown in the loam and in the sand. In the check pots the green yield 

 from the sand series was only 62 per cent of the yield of the plants in 

 the loam, although the average height of the plants in the two series 

 was approximately the same. 



The data presented in Table III are shown graphically in figures 3 

 and 4. 



