52 THE OLIVER PLOW BOOK 



These observations tend to the belief that those who 

 plow deep in the fall with bad results the next year, 

 must not have had fertility on the surface of the plowed 

 field or the winter's freezing destroyed it, and further 

 that the deep plowed field in the spring contains fertility. 



If one regards these deductions as logical, the question 

 as to whether one should plow deep or shallow in the 

 fall or spring must be solely determined by the condition 

 of the land. The farmer must be absolutely certain that 

 he has the plant food elements in the soil either in avail- 

 able or unavailable form, and also whether freezing 

 influences are necessary for the liberation of that food. 

 How can this be determined? 



It is doubtful whether samples taken from the surface 

 of a plowed field and examined by a soil chemist would 

 be of any practical value to the farmer for the simple 

 reason that the soil chemist would be unable to tell as 

 to the availability of these elements in the soil. The 

 most the chemist can do is to determine the amount and 

 kinds of elements that are in the sample submitted. 

 These deductions are apt to be entirely wrong as far as 

 the quantity over the whole field is concerned. 



It is a question whether any man by following this 

 method can ever be sure as to what the soil needs on 

 account of the uncertainty of the amount of plant food 

 elements of all kinds existing in different portions of the 

 field. A much better way for a farmer who is not 

 positive as to what he is going to accomplish by deep 

 plowing is to do a little experimenting of his own. It 

 can be done very successfully providing the experimenter 

 has learned how to handle the different soils as discussed 

 in Chapter V. 



