•224 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



NOTES ON RECENT RESEARCH. 



Effect of Alkali on Roots. 



Alkali Soils, Effects upon Seedling's of certain Components of. 



By Thos. H. Kearney and Frank K. Cameron (Some Mutual Relations 

 between Alkali Salts and Vegetation. Report No. 71, U.S.A. Dep. Agr. 

 p. 7 ; 1902). — In many of the arid districts of the Western United States 

 the soil contains various salts collectively termed " alkali " by the people 

 of the district. The salts most commonly met with are sodium chloride, 

 sodium sulphate, sodium carbonate, sodium bicarbonate, magnesium 

 chloride, magnesium sulphate, and calcium chloride. Frequently they 

 form thin efflorescent crusts on the surface of the ground. Soils con- 

 taining moderate amounts of some of these — notably sodium carbonate or 

 "black alkali" — support little or no useful vegetation. The authors 

 endeavoured to determine the relative harmfulness of each of the 

 commonly occurring salts of alkali lands. Experiments were made with 

 pure salts singly and in mixture with each other, the plants utilised for 

 the work being White Lupin and Lucerne. 



The primary roots of well-developed plants germinated on damp 

 sphagnum were allowed to dip for twenty-four hours into solutions of 

 various strengths of the different salts, and the limits of concentration 

 of each solution which would just permit the roots to live during that 

 time were determined. 



The following results were obtained with White Lupins : — 



Magnesium sulphate ... 7 parts in 100,000. 



Magnesium chloride ... 12 „ „ 



Sodium carbonate . . . 26 ,, „ 



Sodium sulphate ... 53 „ „ 



Sodium chloride . . . 116 „ „ 



Sodium bicarbonate . . . 167 „ „ 



Calcium chloride . . . 1,377 „ „ 



From this table it is clear that the basic radicles or kathions of the 

 salts are more active upon plant tissues than the acid radicles or anions. 



Comparison of the same salts was made in regard to the concentration 

 of each which would prevent any elongation of the roots to take place 

 during twenty-four hours. The following results were obtained : — 



Concentration preventing 

 growth. 



Sodium carbonate . . . 260 parts in 100,000. 

 Sodium bicarbonate . . . 417 „ „ 

 Magnesium chloride . . . 960 ,, ,, 

 Sodium chloride . . . 1,160 ,, ,, 

 Sodium sulphate . . . 1,410 ,, ,, 

 Calcium chloride . . . 1,652 „ ,, 

 Magnesium sulphate . . . 1,680 ., ,, 



That the injurious or toxic effect of solutions of these salts is not 

 merely a function of their osmotic pressures is obvious from a comparison 



