SOILS AND THEIK COMPOSITION. 163 



of corameroial fertilizers now made, the mineral t lements form far 

 the largest portion of their weight. It must be constanth' borne in 

 mind that however minute the quantit}- of a given element required 

 by a plant that atom must be supplied or the plant cannot be brought 

 to perfect maturity. 



Soils suitable for cultivation usually contain all of the necessary 

 elements. But they are often in so close chemical combination that 

 the plant cannot obtain the necessary supply. For it must be 

 constantly remembered b}' cultivators of the soil that the plant can 

 take its food onlv in liquid or gaseous form, and it is the work of 

 the farmer by cultivation and application of the right elements to 

 not only suppl}' lacking elements, but b}' cultivation and application 

 of solvents to dissolve plant food already in the soil so as to be 

 available to the plants. The lexture and mechanical condition of 

 soils has much to do with their capacit}' for absorbing and retaining 

 moisture and fertilizers, qualities on wh'ch every farmer knows much 

 of the value of a soil depends. A knowledge of their origin and 

 their constituent elements is of deep importance in obtaining a 

 thorough acquaintance with soils. 



Soils may be classed, first, as soils which have been formed by 

 decomposition of the rock on which they rest; and, second, as drift 

 soils, which are those which have been carried from the places 

 where thev originally formed by water and other agencies and 

 became mixed with other soils and finally deposited on rock very 

 different, perhaps, from any of the material of the soil above it. 

 The entire soil of New England and the Middle states is composed 

 of drift, therefore \^ must bear in mind there is no uniformity of 

 soil over an}' considerable area, and we often find a marked difference 

 in the soil in different parts of the same field. The value of a given 

 soil depends much upon the kind of subsoil immediately below the 

 plow. A clay soil resting on gravel or sandy subsoil will drain 

 readily and pulverize with the plow and by the frost so as to be in 

 a fine condition for a crop, while the same kind of a soil resting on 

 an impervious cla}' subsoil will retain too much water in wet seasons, 

 and will be too hard when dry for the roots to penetrate. On the 

 other hand, gravelly and sand soils do much better when lying on 

 clay subsoil, as it will hold moisture, which the sands and gravels 

 are not able to do, only to a limited extent. In judging the value 

 of soils, their capacity for absorbing and retaining water must not 

 be overlooked. Our loams will absorb from forty to fifty per cent 



