Effect of Alkali Salts in Soils on Crops 



From Table VII it will be seen that germination was first retarded by 

 the salts when the soils contained but a small amount of moisture. 

 With most of the salts the highest germination was in the wettest sand, 

 while with sodium chlorid the intermediate moisture gave the highest 

 germination. 



It will be noted that in the sand sodium carbonate was more toxic 

 than sodium chlorid. This same relation is also reported later in this 

 paper with sand, although in all the tests with loam sodium chlorid was 

 more toxic than sodium carbonate. A comparison of the limits of 

 growth in sand with those already reported for loam brings out the fact 

 that germination is reduced by a much lower concentration in sand than 

 in loam. This is also brought out clearly in results reported later. 



OUTLINE OF LATER WORK 

 GENERAL METHODS OF EXPERIMENTATION 



A number of experiments were conducted in glass tumblers in which an 

 equivalent of 200 gra. of dry soil was placed. Salts were added to the 

 soil as follows: A stock solution of each salt was made up, containing 

 an equivalent of 10 per cent of the anhydrous salt. The necessary 

 quantity of the stock solution was then added to sufficient distilled water 

 to make the soil up to 20 per cent water on the dry basis. The water 

 containing the solution was thoroughly mixed with the soil on oilcloth 

 and the whole placed in the glass. This method insured an even dis- 

 tribution of the salt through the soil. 



In all cases the soil was made up to 20 per cent wuth moisture. This 

 was about the optimum amount for plant growth. Ten seeds were 

 planted in each glass to a depth of K inch from the surface. After the seeds 

 were planted the glass tumblers were covered with panes of window 

 glass until the plants were up. This prevented evaporation and enabled 

 the seeds to germinate with an even soil-moisture content. 



Counts were made of the number of plants up each day, which made 

 possible a determination of the relative time required for germination in 

 the different treatments. The original moisture content was maintained 

 by adding the necessary quantity of water every day or two. The plants 

 were allowed to grow for two or three weeks, when they were harvested 

 and measured and the dry weights determined. 



The data obtained for each glass therefore included (i) the percentage 

 of germination, (2) the average time required for germination, (3) the 

 average height of plants, (4) the average number of leaves, and (5) the 

 dry matter produced. 



In each test there were 15 glasses for each concentration of salts, and 

 there were 10 concentrations. In addition, there were four check 

 glasses to which no salt was added. This made 154 glasses for each test. 

 In the series there were 24 tests, which gave a total of 3,696 glasses. 



