INTRODUCTION. 11 
alone, instead of on the total weight of dry matter produced, have 
also been omitted. 
The earliest water-requirement measurements appear to have been 
made by Woodward (1699). Lawes (1850) was. however, the first 
to extend his experiments so as to include the entire growth period 
of annual crop plants. References to some of the earlier papers 
dealing with this subject are given by Burgerstein (1904, pp. 154- 
158) in his work on transpiration. The methods employed in some 
of the more recent investigations of the water requirement of plants 
have been summarized by Montgomery (1912). 
EFFECT OF SOIL, FACTORS ON THE WATER REQUIREMENT. 
EFFECT OF SOIL-MOISTURE CONTEXT OX THE WATER REQUIREMENT. 
il'exkov's experiments. 
The effect of soil-moisture content on the water requirement was 
first investigated by LTenkov (1865, p. 162). Buckwheat {Polygonum 
fagopyrum) was planted in five flowerpots containing garden soil, and 
seven plants were grown in each pot. The pots were exposed in the win- 
dows of a room which received the sun at midday. The experiment 
Pagxoul, A. 
1898. Essais relatifs a la transpiration des plantes. Rgpublique Francaise, Departement du Pas-de- 
Calais, Station Agronomique, Bulletin, pp. 10-15. 
Lotngstox, B. E. 
1905. Relation of transpiration to growth in wheat. Botanical Gazette, v. 40, no. 3, pp. 178-195. 
Reprinted as Contributions from the Hull Botanical Laboratory, 67. 
Brittox, J. C, axd Reid, F. R. 
1905. Studies on the properties of an unproductive soil. I". 8. Department of Agriculture, Bureau 
of Soils, Bulletin 28, 39 pp. 
Jexsex. C. A., Breazeale, J. F., Pember, F. R., axd Skixx'er, J. J. 
1907. Further studies on the properties of unproductive soils. U. S. Department of Agriculture, 
Bureau of Soils, Bulletin 36, 71 pp. 
Hartwell, B. L., axd Pember, F. R. 
1908. Relation between the effects of liming and of nutrient solutions containing different amounts 
of acid upon the growth of certain cereals. Rhode Island Agricultural Experiment Station, 
20th Annual Report, 1906-7, pp. 358-380. 
Wheeler, H. J., axd Pember, F. R. 
1908. Effect of the addition of sodium to deficient amounts of potassium upon the growth of plants 
in both water and sand cultures. Rhode Island Agricultural Experiment Station, 20th Annual 
Report, 1906-7, pp. 299-357, 1 pi. 
Krauss, F. G. 
1908. Rice investigations. Report of first year's experiments. Hawaii Agricultural Experiment Sta- 
tion, Annual Report, 1907, pp. 67-90, pLs. 5-9. 
Gardner, F. D. 
1908. Fertility of soils as affected by manures. U. S. Department of Agriculture, Bureau of Soils, 
Bulletin 48, 59 p. 
Reed, H. S. 
1910. Effect of certain chemical agents upon the transpiration and growth of wheat seedlings. 
Botanical Gazette, v. 49, no. 2, pp. 81-109, 9 figs. 
Borroucos, G. J. 
1912. Transpiration of wheat seedlings as affected by soils, by solutions of different densities, and by 
various chemical compounds. Proceedings, American Society of Agronomy, v. 3, 1911, pp. 
130-191, 16 figs. See also Transpiration of wheat seedlings as affected by different densities 
of a complete nutrient solution in water, sand, and soil cultures. Beihefte, Botanisches 
Centralblatt, Abt. 1, Bd. 29, Heft 1, pp. 1-20, 3 figs., 1912. 
Dachxowski, Alfred. 
1912. The nature of the absorption and tolerance of plants in bogs. Botanical Gazette, vol. 54, no. 6, 
pp. 503-514. 
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