220 ANNUAL REPORT OF THE Off. Doc. 



planl food ie preseni in the soil, will not sonic of il be lost before 

 the crops have a chance to use it?" Berein lies one of Nature's 

 most wonderful contrivances for aiding the farmer. Nature has 

 given soil a certain holding power, so that very large amounts of 

 phosphoric acid and potash may be added to a soil and yet none 

 of this will be carried off in the drainage water; it will be held 

 strongly by the soil. And yet as soon as the root of a plant comes 

 through this soil seeking for food, the soil loosens its hold and allows 

 the plant the nourishment it desires. This beneficent result is 

 brought about by the fact that the plant does its feeding at the end 

 of its roots and that the point of each root is continuously secreting 

 a small quantity of acid and this acid dissolves and makes available 

 fhe plant food held so strongly by the soil that rain water could not 

 loosen it. It is possible, therefore, for the farmer to put on at one 

 application enough of phosphoric acid and potash for a generation 

 of crops and have no fear of its being carried out of the soil except 

 as the crops make use of it. All the loss there is by the extra fertili- 

 zation is the interest on the cost of the fertilizer. 



If the same could be said of the nitrogen, then the whole problem 

 of farm fertilization would be much simplified. But, unfortunately, 

 soil has not this holding power for nitrogen and still more unfortu- 

 nately, nitrogen is the most expensive element of plant food. The 

 most difficult problem of farm fertilization is the economical hand- 

 ling of the nitrogen supply. Nitrogen exists in several forms and 

 combinations. It exists pure in the form of a gas and in this form 

 is of no value to most of our crops; it exists in combination as the 

 nitrogen of organic matter in such substances as bone meal, cotton- 

 seed meal, dried blood and the solid portions of barnyard manure; 

 and finally it exists as the nitrogen of ammonia and as the nitrogen 

 of nitric acid or nitrates. In only one of these forms can nitrogen 

 be safely applied in large quantities and that is in the insoluble form 

 of organic nitrogen. So long as the nitrogen remains in this solid 

 form, so long it will not wash out of the soil and be lost. On the 

 other hand, just so long as it remains in this form, it can be of no 

 use to the crop, for all crops take up their food in the liquid form, 

 and this solid organic nitrogen must decay, it must be broken down 

 by the action of the various germs in the soil and changed to nitric 

 acid or nitrates before it can become available to the crop. Then 

 as soon as it has been converted to this available form, if there 

 are no plant roots to absorb it, there is danger that it will be washed 

 out of the soil by the next rain-storm. 



The economical use of nitrogen demands that it be applied in more 

 than one form. If an immediate effect is desired, the nitrogen should 

 be employed in the forms of nitrate of soda or sulphate of ammonia 

 that are available as soon as a showpr washes them to the rooti 



