34 Practical Farming 



Experience There has long been a notion, and it is 



More Reliable g^.-^ prevalent among those who have not 



*^ given close study to these things, that a 



chemical analysis of our soils will at once show us 

 what they need in order to become more productive. 

 But while the chemist can find out the composition 

 of the soil, he cannot determine the availabihty of the 

 materials of which it is composed, and a soil may 

 show a full composition of all the essential elements of 

 plant food and still be a barren soil so far as plant life is 

 concerned, because the existing plant food is not in availa- 

 ble form. It seems that often the physical nature of the 

 soil and its mechanical texture has more to do with its 

 productiveness than the actual amount of plant food it 

 contains. 



A study of the soil through the experimental growing 

 of various plants in plots, with the addition of the different 

 plant foods separately and in various combinations, will 

 help the farmer to Understand the needs of his soil better 

 than any number of chemical analyses. Chemical analy- 

 sis shows that there is a very great difference in soils within 

 very limited areas, and it has also been shown that the 

 roots of plants have a selective capacity, and that some 

 take far more of certain elements than others do. Hence 

 the study of the soil must be continued for several years, 

 and with varying plants, in order to arrive at an intelKgent 

 understanding of its needs. Of this we will treat more 

 fully when we come to the study of fertilizers. 



The common classification of soils as clayey, clay 

 loam, sandy loam, sandy, or peaty, really tells us little 

 in regard to the actual composition of soil, since soils of 



