238 THE MONTHLY BULLETIN. 



research may show — scientific candor dictates that we announce at 

 the present time there is no evidence for such a belief. 



Now it is true that the appearance, flavor, size and other characters 

 of, for example, fruit, may be improved by the addition of a given 

 fertilizer element; but that, as mature reflection will soon show, is no 

 indication that that fertilizer element has any specific effect. It is only 

 an indication that we are supplying a missing material without which 

 we can not expect the plant in question to do well, and thus, by making 

 its general conditions for life better, we also produce a better fruit. 

 Any one who has the slightest conception of the complexity of the soil's 

 composition from all points of view, can readily realize that the appli- 

 cation of a given fertilizer, while it may in the end give, for example, 

 a sweeter fruit, may as a matter of fact have no power itself to change 

 the sugar content of a fruit, but may have power indirectly to affect 

 many of the processes concerned in the production of the plant's food, 

 or the plant's growth, which will operate toward that end. 



The only case on record of a specific effect of a plant food element 

 which we have some good reason to believe is correct, is that avaihihle 

 nitrogen does give a darker green color to the leaves of plants and 

 increases the growth of leaves and stalks. Even that, however, as 

 experience shows, may not be thoroughly reliable, since larger additions 

 in excess of phosphoric acid or potash may offset that effect, and instead 

 of causing the much deeper color and larger vegetative growth of 

 plants, we may get a thoroughly well balanced and normal plant which 

 will ripen normally instead of having its ripening period put off, as it 

 does when nitrogen is in excess. In other words, the proportion or 

 relationship between the amounts of fertilizer present in soils, which, 

 as present research is beginning to show, may be a very important 

 factor in the kind of plant which is grown on a given soil, may influence 

 this growth entirely and not the absolute amount nor the specific effect, 

 of the several important chemical elements of plant food. 



CONCLUDING REMARKS. 



My object in making the statements just read has not been t(j 

 destroy, but to build up. They are not iconoclastic in nature but con- 

 structive, for it is only through a dispassionate examination into our 

 ideas and a searching inquiry into their intrinsic value that we may 

 hope, by recognizing our weaknesses and our errors, to build up a more 

 stable structure to represent progress in soil fertility. 



Before making my closing remarks, I desire to make a statement in 

 justice to everything and everybody concerned in my discussion. I 

 do not desire by any manner of means to convey the impression that 

 I recommend against the use of commercial fertilizers or fertilizers 

 of any kind; quite the contrary. I am a strong advocate of the use 

 of fertilizers wherever I can have indubitable proof that such ferti- 

 lizers are needed and can return profit. I am, however, opposed to 

 their use by hit or miss methods in which one is obliged to take chances 

 on the possibility of the fertilizers doing some good. My only object 

 in this paper is to point out that we can not by a laboratory examin- 

 ation of the soil (by the ordinary chemical methods of soil analysis), 

 determine what fertilizers are needed. That is the only phase of the 

 fertilizer question which I wish to emphasize here. I may also add 



