54 STATD POMOLOGICAL SOCIETY. 



not get the full value of the others. For instance, if there is a 

 lack of phosphoric acid, then your trees are not getting the full 

 effect of the nitrogen and the potash which the soil contains 

 because the trees require the phosphoric acid in order to make 

 their normal, satisfactory growth. So it may be possible that 

 either more nitrogen or phosphoric acid is needed by the trees 

 where Mr. Dawes applied only the sulphate of potash. It is 

 possible that if with the sulphate of potash he had applied either 

 nitrogen or phosphoric acid, he would have gotten the returns 

 that he was looking for. The only way that could be deter- 

 mined would simply be to make the test, to apply phosphoric 

 acid with the potash, or the potash with nitrogen, and note the 

 results. In that way, and in that way only, could one tell just 

 exactly what the trees need. 



Now the notion is very commonly expressed by fruit growers 

 and farmers generally, that a chemist can analyze their soil and 

 tell them just what it needs. I have frequently been asked, in 

 my contact with fruit growers and other farmers, if I can have 

 samples analyzed for them, thinking that if the chemist analyzes 

 their soil that is all they need to know. All the chemists in the 

 wide world could not tell you what your soil needed to make it 

 give the results that you are after, and that is no disparagement 

 to the chemist either ! The chemists' methods and the methods 

 of the tree are different and do not give the same result. The 

 chemist can analyze your soil. He can tell you how mucii phos- 

 phoric acid there is in it and how much nitrogen and whatever 

 else he may examine it for. That is good as far as it goes, but 

 he cannot tell you how much of the plant food which a soil con- 

 tains the plant can get out, and that is where the rub comes with 

 the agricultural chemist. The methods that the plant uses and 

 those of the chemist are different and give different results. 

 That is to say, no methods which are known to chemistry will 

 reveal just how much of any plant food is available to the plant 

 itself by means of the methods which the plant uses in getting 

 that food. The only way you can learn this is to do what Prof. 

 Roberts of Cornell University used to say so commonly to his 

 boys and at horticultural meetings — you have got to "question 

 the soil" and find out in that way. This can be done by making 

 applications of pure chemicals in different combinations, apply- 



