Oct. 4, 19IS 



Effect of Alkali Salts in Soils on Crops 



15 



these salts can readily be determined by consulting figure i. The number 

 at the bottom of each triangle refers to the concentration of soluble salts 

 in all the glasses of that triangle expressed in parts of anhydrous salt 

 per million parts of dry soil. 



An examination of figure 2 shows that some seeds germinated in all 

 glasses up to a concentration of 4,000 p. p. m., but that at 5,000 p. p. m. 

 there was no germination in the glass having all sodium chlorid, and only 

 germination in one of the glasses with three-fourths sodium chlorid. 

 In the part of the triangle toward the sodium chlorid the germination 

 gradually decreased as the concentration increased. The sodium car- 

 bonate and sodium sulphate showed almost a complete germination up 

 to 10,000 p. p. m., or I per cent of salt. 



Check^NoSalt 



4.oooppm. 



sfiooppm. 



e.oooppm. toooppm. Stoooppm. 9,ooop.p.ni. to.ooopprk. 



. = One plant. — =0.1 gm. dry matter. 



IG. 2.— Diagram showing the number of wheat plants up and dry matter produced in 24 days on Green- 

 ville loam with sodium sulphate, sodium carbonate, and sodium chlorid in different combinations and 

 concentrations. 



The greater toxicity of sodium chlorid as compared with sodium car- 

 bonate was somewhat of a surprise, since most of the literature on alkali 

 considers sodium carbonate, or black alkali, as being by far the most 

 harmful of the alkali salts. The results given here agree with those 

 found in the experiments of 191 2 and 19 13 and are also borne out by 

 the results shown in figures 7, 12, 17, 18, 19, 20, 21, and 22, where dif- 

 ferent crops are compared. 



In the glasses that received sodium carbonate the surface was black 

 with dissolved humus and was somewhat crusted, showing that the phys- 

 ical condition had been injured. Notwithstanding this fact, seeds germi- 

 nated in the soil and the plants grew for three weeks with no great injury 

 except a slight blackening of plants at the surface of the soil with higher 

 concentrations. 



Figure 3 shows results for the chlorids of potassium, calcium, and 

 magnesium. These chlorids are not as toxic as the chlorid of sodium, 

 5770°— 15 2 



