468 ANNUAL REPORT SMITHSONIAN INSTITUTION, 193 8 



California Agricultural Experiment Station has no recommendations 

 to offer at this time for the general use of the water-culture method, it 

 seems proper and necessary that those who wish to experiment with 

 this method on their own responsibility should have accessible a 

 popular account of the information now available from the researches 

 of the Agricultural Experiment Station. 



The method of water culture is, as previously indicated, not the 

 only one for growing plants without soil. Several other experiment 

 stations have developed large-scale techniques of sand or gravel 

 culture. These involve the periodic flooding, or subirrigation, of a 

 solid medium with nutrient solutions similar to those employed in 

 the water-culture method. Some investigators hold the opinion that 

 the sand- or gravel-culture methods have certain advantages in 

 practical use over the water-culture method, particularly in respect 

 to conditions of aeration of the root system. 7 



PRINCIPLES AND APPLICATION OF THE WATER-CULTURE 



METHOD 



The purpose of this circular is to give an account of the water- 

 culture method as a means of supplying mineral nutrients and water 

 to plants. The absorption of nutrient salts and water are only two 

 of the physiological processes of the plant. In order to evaluate the 

 possibilities and limitations of any special technique for growing 

 plants, one has to understand the significance of other interrelated 

 processes, especially photosynthesis, respiration, transpiration, and 

 reproduction. 



IMPORTANCE OF CLIMATIC REQUIREMENTS 



Many inquiries have been received on the possibility of growing 

 plants in water culture in dimly lighted places, or at low temperatures, 

 under conditions which would prevent growth of plants in soil. Obvi- 

 ously, no nutrient solution can act as a substitute for light and suitable 

 temperature. If doubt is entertained of the suitability of a particular 

 location or season for the growth of any kind of plant, a preliminary 

 experiment should be made by growing the plant in good garden soil. 

 If the plant fails to make satisfactory development in the soil medium 



» Further information on the sand- and gravel-culture methods may be obtained from the following 

 publications: 



Withrow, R. B., and Biebel, J. P., Nutrient solution methods of greenhouse crop production. Indiana 

 (Purdue Univ.) Agr. Exp. Stat. Circ. 232, pp. 1-16, 1937. 



Biekart, H. M., and Connors, O. H., The greenhouse culture of carnations in sand, New Jersey Agr. 

 Exp. Stat. Bull. 688, pp. 1-24, 1935. 



Shive, J. W„ and Robbins, W. R., Methods of growing plants in solution and sand cultures, New Jersey 

 Agr. Exp. Stat. Bull. 636, pp. 1-24, 1938. 



Eaton, Frank M., Automatically operated sand-culture equipment, Journ. Agr. Res., vol. 53, pp. 433-44, 

 1936. 



Chapman, H. D., and Liebig, George F., Jr., Adaptation and use of automatically operated sand-culture 

 equipment, Journ. Agr. Res., vol. 56, pp. 73-80, 1938. 



