Reprinted from Soil Science 

 Vol. XIII, No. 3. March, 1922 



^^ THE EFFECT OF DRYING SOILS ON THE WATER-SOLUBLE 

 J CONSTITUENTS! 



I A. F. GUSTAFSON 



New York Slate College of Agriculture at Cornell University 



Received for publication, May 1, 1921 

 INTRODUCTION 



The effect of dr>'ing and of burning soil on the growth of crops was noted in 

 the field by the Roman farmer many years before the beginning of the science 

 of soils. At first, improvement in the crop was attributed to the well known 

 effect of drying on the physical condition of medium and fine-grained soils; 

 later, as chemistry developed, the increased growth was considered to be due 

 to some chemical change which occurred in the soil during the process of 

 drying; while a more recent idea is that the improvement is brought about by 

 readjustment in the microscopic life of the soil. 



For several decades greenhouse growers have practiced heating the soil to 

 kill various plant and animal enemies of the crop. In many instances the 

 improvement in growth was greater than could have been affected by steriliza- 

 tion alone, the rank growth of stem and dark green color of leaf being par- 

 ticularly noticeable. Some growers have found it necessary to withhold a 

 portion of the nitrogen usually supplied, to avoid excessive growth of the 

 vegetative portion of the plant and thus permit proper fruiting. 



It is the purpose of this paper to review the observed effects of drying and 

 heating soils, and to present some experimental data indicating the effect of 

 drying, and of heating at 105°C., on the amount of total water-soluble solids 

 recovered by extraction with distilled water. 



REVIEW OF LITERATURE 



Davy (17) says: 



"The improvement of lands by burning was known to the Romans. It is mentioned by 

 Virgil in the first book of the Georgics. It is a practice still much in use in many parts of 

 these islands; the theory of its operation has occasioned much discussion, both amongst 

 scientific men and farmers. It rests entirely upon chemical doctrines; and I trust I shall be 

 able to ofi'er you satisfactory elucidations on the subject." 

 Also: 



"Whenclay or tenacious soils are burnt, .... they are brought nearer to a state 

 analogous to that of sands All poor siliceous sands must be injured by it (burn- 

 ing), and here practice is found to accord with the theory." 



1 A thesis submitted to the Faculty of the Graduate School of Cornell University in 

 partial fulfillment of the requirements for the Degree of Doctor of Philosophy, September, 



1920. 



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