SOME SILVICULTURAL ASPECTS AND PROBLEMS OF THE SOIL. 35 



4. Some Silvicultural Aspects and Problems 

 of the Soil. 



By G. K. Fraser, M.A., B.Sc, 

 Forestry Department, University of Aberdeen. 



Owing to the greater importance of agriculture in the earlier 

 stages of rural economic development, the investigation of the 

 influence of soil properties on plant growth was at first under- 

 taken almost entirely from an agricultural standpoint. Although 

 the fundamental principles which regulate the growth of normal 

 plants are the same whether these plants be of horticultural, 

 agricultural, or silvicultural value to man, yet the raw materials 

 and final products desired, as well as the conditions under which 

 these are utilised, are so distinct in their nature as to give to the 

 silvicultural branch of soil science a quite specific standpoint of 

 its own, both as regards the soil factors specially involved in the 

 production of forests, and also the most suitable methods by 

 which these factors may be controlled and used to the best 

 advantage. 



The modern development of agriculture may be dated from 

 Liebig's work entitled Chemistry in its Application to Agriculture 

 and Physiology, in which he set the subject of nutritional plant 

 physiology upon a fairly correct scientific foundation. At the 

 same time, owing to his extreme chemical outlook, he rather 

 alienated the plant physiologist from the study of soil science, 

 with the result that the work of the agricultural chemist obtained 

 a somewhat exaggerated importance as regards plant nutrition 

 as a whole. Although even the agricultural outlook upon soil 

 problems has moved slightly away from this purely chemical 

 foundation, yet it still has and must always have a more intense 

 chemical outlook than belongs to general plant physiology, 

 since agriculture is devoted to the artificial stimulation of 

 abnormal growth in localised organs of its crop plants, not 

 necessarily of the plant as a whole, a stimulation which requires 

 usually abnormal soil conditions as regards one or more of the 

 nutrients necessary for the particular development desired. 



On the other hand, within recent years more attention has 

 been paid to the physical condition of the soil in its bearing on 

 plant growth, and since in forestry the direct chemical ameliora- 

 tion of the soil is for all practical purposes impossible, the effects 



