No. 6. DEPARTMENT OF AGRICULTURE. 177 



conditions favorable for tlie changes that must tal^e place in germi- 

 nation, growth and maturation, but also the chemical transforma- 

 tions that render inert plant food available for future crops. 



It is with the improvement of these three phases of the soil that 

 we must deal, if we are to build them up in a natural way. It 

 is also true that soils derived from the same rock formation are not 

 equally good, for even those of similar origin may vary widely in 

 their quality, and more especially in their physical and chemical 

 character; some are too open and porous, contain too much sand, 

 become too hot Lnd are poor in plant food; others are too heavy 

 and compact, and while they contain an abundance of plant food, 

 it is difficult for the plant roots to penetrate and absorb it. Others 

 contain so little vegetable matter that there is no "life;" they be- 

 come hard, and break up into clods and lumps, and if by reason of 

 good tillage are made hue, they puddle with the first rain. These 

 are deficiencies that are to be made good by the proper direction of 

 natural agencies, which may, on the one hand, make the light soil 

 cooler and more compact, and absorptive of water and plant food, 

 and, on the other hand, the heavy one less compact, and to freely 

 permit the circulation of air and water, thus changing the chemical 

 character in such a way as to enable the plants to obtain an abun- 

 dance of food otherwise unavailable. 



In a general way, the four chief ingredients in soils are sand, clay, 

 lime and vegetable matter, or humus, and which, existing in proper 

 proportion, make them productive. Any one of these in themselves 

 would not make a good soil, yet each is essential in order that a 

 good soil may be made. If we assume that a farm is divided into 

 the tw'o opposite types, a heavy clay and light sand, both deficient 

 in vegetable matter and in lime, though wdth good natural drainage, 

 we have a w^orking basis for a discussion of the methods of im- 

 provement by natural agencies which will apply quite as well to 

 the numerous intermediate types. 



The deficiencies in the clay soil are that it is too cold, air does 

 not penetrate freely, and it does not warm quick enough to enable 

 an early planting and quick germination of seed; it remains wet and 

 soggy until hot w^eather, when frequently it becomes too dry, and 

 is then hard and compact, and the plants suffer because they can- 

 not obtain food. In wet w^eather the water does not evaporate 

 rapidly — it becomes water-logged, and plants scald and die. 



The sandy soil possesses opposite characteristics. Its deficiencies 

 are that it is too open and porous, the w^ater moves too freely. It 

 is easily worked, and may be handled at any time without serious 

 damage to its physical cfiaracter, but when dry times come, the soil 

 becomes too hot and plants burn and wither; the crop is of no 

 value. If it is too wet, they grow rapidly at first, then become yel- 

 low, and the crop is a failure, because the food contained is not 

 abundant, and the rains carry it away. 



In the first case, what is needed is to direct the natural agencies, 

 sun. air and water, in such a way as to make that soil less com- 

 pact and adhesive, and to permit the air to penetrate more readily, 

 the water to move more freely, and thus encourage chemical changes, 

 as well as providing for the activities of bacterial life, which have 

 a tendency both to add to and to set free the plant food that is 



12—6—1907. 



