200 The Plant World. 



taking collection of data and the theoretical considerations 

 and conclusions are too voluminous for reproduction but should 

 be duly weighed by students of plant distribution.^ — V.M.S. 



The choice of crops for alkaline land is discussed by Thomas 

 H. Kearney in Farmer's Bulletin 446 of the United States 

 Department of Agriculture. To get rid of the excess of salts 

 in alkali soils by flooding and drainage is expensive, and often 

 impracticable, hence it becomes necessary to investigate care- 

 fully the relations and possible adaptations of various crop plants 

 to such soils. Thus a question primarily economic becomes one 

 of great scientific interest andinspiteof its difficulties good pro- 

 gress is being made towards its solution. The author's state- 

 ment of principles suggests at once the complicated nature of 

 the problem. In the first place it is shown that the mere state- 

 ment of the percentage of alkali in a soil tells us little about how 

 plants will be affected. Some plants which can endure one 

 percent of alkali if present in a heavy soil, would quickly perish 

 in a sandy soil containing the same quantity and the same kind 

 of salts, the reason being that the heavier soil can hold more 

 water. Again in regions of winter rainfall like California a 

 winter crop might succeed better in alkali land of a given con- 

 centration that a summer crop that is actually more resistant. 

 The vertical position of a given quantity of alkali in the soil in 

 relaiton to the depth reached by plant roots is also an important 

 matter. Thus, for example, a comparatively small quantity 

 of alkali near the surface will prevent crops starting that 

 might grow well if a heavy rain or irrigation has occurred just 

 before planting, resulting in driving much of the alkali into 

 lower depths of the soil. Crop plants adapted to difi"erent 

 grades of alkali in soils are discussed at length and useful practi- 

 cal suggestions are given which give the impression of careful 

 scientific weighing of the complicated interrelations of the 

 factors involved. — V.M.S. 



William Hussell Dudley, Professor of Systematic Botany 

 in the Iceland Stanford Junior University from 1892 till 1911, 



