Oct. 4, 191 5 Effect of Alkali Salts in Soils on Crops 3 



Nesslcr in 1877 (9) stated that 0.5 per cent of cooking salt (sodium 

 chlorid) injured the germination of rape, clover, and hemp, and that 

 wheat withstands this solution, but is injured by a i per cent solution. 



Hilgard was a pioneer in the study of alkali soils and as early as 1877 

 began pubUshing results on his investigations in California. From that 

 time to the present his contributions, together with those of Loughridge, 

 his associate, have constantly enriched the literature. Their results are 

 contained in numerous publications of the California Agricultural Experi- 

 ment Station and were well summarized by Hilgard in 1906 (11). 



An excellent review of the work done on alkali in the United States 

 up to 1 905 is also given by Dorsey (6) . A large proportion of the work 

 on alkali in this country has consisted of the analysis of soils for the 

 determination of the presence of various alkali salts. 



A number of workers, however, have investigated the amounts of the 

 dififerent salts necessary to inhibit crop growth. Hilgard (10) and 

 Loughridge (17) made numerous studies of the alkali content of Cali- 

 fornia soils and the limits of concentration of the various salts at which 

 cultivated and native plants cease to grow. 



Buffum (3), Slosson (23), and Knight and Slosson (15) in Wyoming 

 carried on many experiments on the effect of alkali on the germination 

 of seeds and growth of crops. From their results they concluded that 

 there is a regular decrease in the germination of seeds as the osmotic 

 pressure increases; and there is no apparent difference between sodium 

 or potassium, or between the sulphate and chlorid of the same or differ- 

 ent salts. It will be noted that this conclusion is not borne out by the 

 data contained in the present paper. 



Headden (8), working with sugar beets, found that varieties differed 

 in their resistance to alkali. He also determined the effect of sodium 

 carbonate, sodium sulphate, and magnesium sulphate on the germina- 

 tion of sugar-beet seed. He concluded that — 



The best seed germinated freely in soil containing as much as o.io per cent of sodium 

 carbonate but the plants were attacked by as much as 0.05 per cent and it is doubtful 

 whether any of them can survive when there is as much as o.io per cent of this salt 

 present in the soil. Sodium sulphate affects the germination to a much less degree, 

 even when it is equal to 0.90 per cent of the air-dried soil, but it is injurious when 

 present in larger quantities. When both sodium carbonate and sodium sulphate are 

 present inequal quantities, the action of the carbonate, or black alkali, is only slightly 

 or not at all mitigated . Magnesium sulphate retards, but does not prevent germination 

 when present in quantities equal to i per cent of the air-dried soil. 



Stewart (25) made germination tests of a number of crops in soil to 

 which different quantities of alkali salts had been added. He found 

 sodium carbonate to be the most injurious of the alkalies with most crops. 

 However, with white clover and red clover white alkali proved as injuri- 

 ous as the black. In their resistance to alkali the cereals stood in the 

 following order: Barley, rye, wheat, and oats, barley being the most 



