CONTEXTS. 



Page. 



The Effect upon Seedling Plants of Certain Components of Alkali Soils. By 

 Thomas H. Kearney and Frank K. Cameron: 



Introduction 7 



Methods of experiment 9 



Salts employed 9 



Plants selected for experiment .--,-.. 10 



Details of manipulation . . 13 



Determination of the limit of endurance 15 



Results with pure solutions - 19 



Concentration maximum permitting survival of the roots 19 



Concentration minimum prohibiting elongation of roots 24 



Results with less soluble salts 25 



Results with mixed solutions 27 



Magnesium sulphate in mixtures 29 



Magnesium chloride in mixtures 32 



Sodium carbonate in mixtures 33 



Sodium sulphate in mixtures 35 



Sodium chloride in mixtures 36 



Calcium chloride in mixtures 37 



Sodium bicarbonate in mixtures ... . . 37 



Calcium sulphate and calcium carbonate in mixtures 37 



General significance of results with mixed solutions 40 



Stimulating effect of dilute solutions 47 



Economic importance of the results _ _ . 52 



Summary 54 



Conclusion 55 



Bibliography 56 



Formation of Sodium Carbonate, or Black Alkali, by Plants. By Fr.^nk K, 

 Cameron: 



Introduction _ . 6^ 



Creosote bush 61 



Greasewood 63 



Absorption of mineral constituents by the plant 65 



Comparison of analyses 68 



Summary 69 



Resistance to Black Alkali by Certain Plants. By Frank K. Cameron: 



Introduction li 



Method of examination 7^ 



Distichlis spicata 71 



Isolation and identification of acid exudation 72 



Hydroscopic salt on the plant surface. 73 



Selective absorption of soil constituents 73 



Function of the acid exudation 74 



Phosphorus in the plant 74 



Ash analyses . 75 



Suaeda intermedia and Atriplex bracteosa 76 



Summary 77 



5 



