No. 6. DEPARTMEJNT OF Ai-'.KICULTURE. 457 



The Biological Character of Soils. 



The physical character of soils, also, has an important bearing 

 upon the question of the living organisms in the soil, whose activity 

 in improving soils is very important, though not api)reciated until 

 recent years, and not yet fully understood. Soils are not, as has 

 been believed to some extent in the past, dead things, serving only 

 as banks from which we may draw out deposits of materials, already 

 in a state capable of serving as food, but are rather laboratories, 

 in which the natural agencies, already described, are actively en- 

 gaged in working over the raw materials, converting them into 

 forms available for use. They contain millions of living creatures, 

 small to be sure, which depend for their life upon air, moisture and 

 the insoluble matter in the soil, the latter of which in the transfor- 

 mation which takes place in the growth of organisms, is changed 

 into forms which the plant can absorb. 



It must not be forgotten that these lower orders of life depend for 

 their best growth and development upon the conditions that are fa- 

 vorable for the life and growth of the higher orders of life, namely, 

 food, moisture and warmth, and as the farmer by his practice makes 

 the conditions favorable for their life and thus encourages their 

 growth, he provides for a more rapid change of soil substances, while 

 on the other hand, if he by his practice prevents or in any way re- 

 duces the opportunities for the life and growth of these agencies, he 

 reduces in just that degree the i>ossible usefukiess of the potential 

 fertility of such soil. For example, the farmer who allows his soil by 

 improper treatment to become compact and hard, thus not permit- 

 ting the free movement of air and water, is making the conditions 

 unfavorable for the living organisms in the soil, and is preventing in 

 part the change of insoluble into soluble substances, the result of 

 which is food for the plant; while, on the other hand, the farmer who 

 by his practice makes the conditions for life in the soil favorable by 

 controlling the movements of water , warmth and air, obtains from 

 his soil a larger crop, because he has directed in an intelligent way 

 the agencies which assist in the change of soil substance, and which 

 is necessary in order to insure an abundance of available food, which 

 assists in the natural improvement of soils. Improvement of soils 

 may, therefore, be brought about, and without expense, by assisting 

 Nature, in changing for the better both the chemical and physical 

 character of soils, and by controlling the movements of the soil 

 solutions. Efforts in this direction may be called ''natural methods 

 of improvement," because the aim is to assist Nature in her work 

 which results in changing potential or possible into active, or actual 

 fertility, rather than to add to the soil substances which contribute 

 directly to the store of active constituents. 



