THE SOIL AND SOIL FORMATION 65 



to periods of drouth. Many light soils are far better 

 adapted to forest crops than to field crops. 



Medium soils are made up of sand and clay, coarser 

 and finer rock particles, mixed. They are sufficiently 

 open to absorb large quantities of water, and they have 

 the ability to retain it. They are usually productive 

 soils, having large quantities of organic matter rather 

 firmly " fixed," among the mineral soil particles. These 

 soils provide the best home for the roots of plants, being 

 neither too dense for the easy penetration of the roots, 

 too close for the circulation of air, water and heat, nor 

 too drouthy; and they provide a healthy place for those 

 bacteria which are friends of the crop. These medium 

 soils sometimes are given names indicating their geolog- 

 ical origin, as till soils, bowlder clay soils, loose soils and 

 alluvial soils. 



On the prairies these soils are nearly black, and bear a 

 rich covering of native grasses. In the timber sections 

 they carry a heavy growth of trees, usually of the 

 deciduous class. Color is not a very good general index 

 to the richness of a soil ; some rich soils are black, others 

 red, yellow or other lighter shades. 



These mixed soils are the golden mean : they form the 

 kind of land upon which every farmer should be am- 

 bitious to establish himself and his family. Such soils 

 often sell below their real value. They are the lands 

 on which usually may be raised the best crops. These 

 soils are most suitable for mixed and intensive systems 

 of farming. They are adapted to grains, grasses, cul- 

 tivated crops, roots, garden vegetables, small fruits and 

 forest trees ; in fact, to almost all staple crops for which 

 the latitude is favorable. 



Peaty soils, formed in wet places by the accumulation 

 of vegetable matter in the water, where it decomposes 

 only very slowly, differ from the three classes of soils 

 named above in that they contain little mineral but 



