INTRODUCTION 5 



is often undesirable to use a fertilizer that readily dissolves 

 in water. Very soluble manures may actually wash out of 

 the soil before the plant can obtain its proper share of the 

 nourishment. 



In considering the actions of fertilizers on the plant and 

 on the soil it is always important to remember that in no 

 sense is such a series of actions a static matter. The plant 

 itself is undergoing rapid chemical change and the soil is 

 full of life. When a fertilizer is applied to the soil, chemical 

 change begins at once and may go on for a long time. These 

 chemical changes induce changes in the development and 

 rates of growth of organisms in the soil from the common 

 earth-worm down to bacteria. The equilibrium of the soil 

 is upset and will only be re-established after an interval 

 of time. In some cases this interval of time is short, but in 

 others may last several years. In addition to the above, 

 there are many secondary points of practical importance. 

 A manure to be successful must be well distributed. A little 

 consideration will at once show that the distribution of 

 fertilizers is a difficult problem. There is no more important 

 point in presenting any commodity to the consumer than 

 placing it on the market in a uniform condition. The same 

 point is just as true of the products of the field as of the 

 factory. The soil is not by any means uniform by nature, 

 and all efforts must be made to correct the irregularities 

 and not intensify them by irregular applications of fertilizers. 

 Soluble fertilizers have the great advantage that the rain 

 distributes them automatically. Unfortunately the distri- 

 bution by this means is only very slight in a horizontal 

 direction although in a vertical direction it is much more 

 complete. If we imagine a dressing of a hundredweight or 

 so applied to an acre and that all the grains of the fertilizer 

 are about one-tenth of an inch in diameter, then there would 

 be about one such grain for each square inch. So that even 

 if we had a perfect distributing machine, the distribution 

 of such a fertilizer would leave much to be desired, since the 

 root hairs of the plant are very small and numerous, and if 

 many of them fail to get their share of plant food there is sure 



