1913] CURRENT LITERATURE 515 
workers, the methods employed have as a rule been crude and inexact, leading to 
much uncertainty in the results. Still it is evident that there was an increase 
in the water requirement when the soil moisture content approached either 
extreme; when the soil was deficient in any plant food element; when the 
amount of soil used in the i t was small; and when shading of the plants 
occurred. Atmospheric conditions profoundly affected the water require- 
ment, being greater in dry than in moist air. 
The extensive experiments of the present investigators in 1910 and 1911 
were conducted at Akron, Colo., with plants grown in water-tight pots con- 
taining about 115 kilos of soil each, so sealed that the loss of water was limited 
to that resulting from the transpiration of the plants, water being added as 
required. Among other results, it was found that wheat consumed an average 
of 507 kilos of water for each kilo of dry weight produced, and taking this as 
the standard (100), the relative water requirements of certain other plants were 
as follows: alfalfa 211; rye 143; oats 122; barley 106; potato 88; maize 73; 
sorghum 60; millet 54; and such weeds as Amaranthus retroflexus and Salsola 
pestifer 63. These results would indicate the great suitability of sorghum and 
millet for semi-arid regions. The bulletins contain a mass of detail and much 
additional data valuable to students of the agriculture and ecology of the 
great plains—Gro. D. FULLER. : 

Agriculture on acid lands.—It has long been known that moors and heaths 
have acid soil, and many ecological classifications, such as that of WARMING, 
regard acidity as the chief determining factor of the vegetation. In several 
interesting and important papers, CoviLLe* has given the results of some 
experiments that should almost revolutionize certain phases of agricultural 
Practice. As is well known, various species of Vaccinium and Gaylussacia are 
commonly sold in the markets as blueberries and huckleberries, and yet are 
not cultivated, as are most other commercial fruits. Many attempts have 
made to cultivate these berries, and their failure is attributed by CoviLLE 
to the fact that their cultivation has been attempted in rich garden soil. Ordi- 
nary cultivated plants, such as alfalfa or roses, grow well in rich garden soil 
and poorly in peat, unless the acidity of the latter is neutralized by lime. The 
blueberry, on the other hand, grows poorly in garden soil, thrives in peat, and 
grows poorly in peat neutralized by lime. After describing the root fungi and 
their probable réle in making nitrogen available, the author gives directions 
for germinating and growing blueberries, showing that fruiting plants can be 
a 
* Covitte, F. V., Experiments in blueberry culture. U.S. Bur. Plant Ind. Bull. 
193. Pp. 100. pls. 18. figs. 3I. 1910. 
——,; The formation of leaf mold. Jour. Wash. Acad. Sci. 3:77-89. 1913. 
—, Directions for blueberry culture. U.S. Dept. of Agric. Circular 122. 
Pp. 11, IQ13 
» The agricultural utilization of acid lands by means of acid-tolerant crops. 
US. Dept. of Agric. Bull. 6. pp. 13. 1913. 
