Cultural First Principles. 



By G. S. BOULGER, F.L.S., F.G.S., late Professor of Natural History in the 

 Agricultural College, Cirencester, 



II. The Natuke of the Soil. 



The science of geology as usually taught is of little use to the prac- 

 tical forester. Except where questions of water supply arise he need 

 care little for gault, lias, or oolite, and certainly cannot afford the 

 time or mental labour necessary to enable him to recognise strata by 

 their fossils. The scientific look of an advertisement of " grasses for 

 the different geological formations " pays, no doubt, but, as a matter 

 of fact, it would puzzle an astufe botanist to say whether he was on 

 clay of liassic, Oxfordian, Kinmieridgian, aptian, albian, or wealden 

 age, judging merely from the flora. The " father of English geology," 

 William Smith, was thus led to confuse formations of very different 

 geological age, though physically alike, under the name " oak-tree 

 clay," from the luxuriance of that species upon them. Except in 

 very new countries the cultivator now-a-days can procure a map of 

 the geology of his district ; but he will not require such assistance to 

 enable him to distinguish a clay from a sandstone, or gravel from a 

 limestone. In fact, the cultivator requires a knowledge not of geo- 

 logy, but of the as yet unnamed and unrecognised science of soils. 



The soil plays two parts with regard to trees : it gives them a solid 

 basis to grow upon, and it supplies them with water, containing in solu- 

 tion some of the substances necessary for their nutrition. By far the 

 greater part of the bulk of our forest trees is made up of carbon, 

 derived from the carbonic acid or carbon dioxide of the air, in com- 

 bination with the elements hydrogen and oxygen, derived from pure 

 water. 



Since, however, plants cannot take in solid food, all the so-called 

 inorganic substances they require must be introduced in solution 

 through the roots. The greater part of this — lime, silica, potash, 

 soda, magnesia, and phosphorus, being returned annually to the soil 

 by the falling leaves and fruit, it will be seen that the physical cha- 

 racters of a soil, may well be niore important than its chemical 

 composition. Nevertheless a chemical analysis of the soil mny be 



