148 MINNESOTA STATE HORTICULTURAL SOCIETY. 



ACIEICULTITRAL CHE]\[ISTRY. 



AGRICULTURAL CHEMISTRY. 



PROF. HARRY SNYDER, ST. ANTHONY PARK. 



Mr. President, ladies and gentlemen: 



The subject assigned to me, agricultural chemistry, is such an exten- 

 sive one that I shall take the liberty of limiting it to a general consider- 

 ation of some of the present views in regard to the functions of the ash 

 elements in plants. 



Whenever a plant is reduced to ashes by burning, there are always defi- 

 nite building materials present, and whenever any of these elementary 

 mineral substances are absent from the soil no plant can live. 



Not less than fifty years ago a prize was offered for a solution of the 

 then vexed question, "are the ash constituents necessary to the plant 

 economy, or are they accidental, in as much as the plant takes up such a large 

 quantity of water and so must of necessity take up what mineral mat- 

 ters are in solution, as well?" So it will be seen that what little is known 

 in regard to the mineral matter in our plants is of a comparatively re- 

 cent date. To the labors of Liebig, Wolf, Knapp and many others, we are 

 indebted for our limited knowledge of the functions of the plant ash. 



The methods employed by these men are familiar to many of you— how 

 plants were fed on a carefully prepared mineral diet, in which one plant 

 element was supplied in a meagre allowance and then again in liberal 

 ration. 



When lime was withheld from the young and growing plant it was ob- 

 served that no new organic matter was produced, when withheld from 

 the more mature plants the effect was not so marked. Numerous experi- 

 ments with this element soon indicated that lime was necessary to the 

 plant in the early stages of its growth. In this regard plants are quite 

 like animals, in as much as they require the larger portion of their lime 

 while young. The mature animal or plant cannot assimilate the lime in 

 Its later stages, so that it will take the place of the lime that should 

 have been assimilated in its early stages. 



Of magnesium, an element quite like calcium (or lime), only a small 

 amount is required, and in its absence the plant will grow, but the seeds 

 from such plants possess but little vitality. The presence or absence of 

 iron is extremely marked in the plant. When iron is withheld the color- 

 ing or greening of the chloryphyle grains cannot take place. Just how 

 the iron effects this change is not known. This mineral occurs in the 

 smallest quantity of anyone of the elements, and is seldom absent from 



any soil. 



Potassium, familiar to us as potash, is never found wanting in any 

 plant, and, in general , it is quite equally and evenly distributed in all parts 

 of the plant, and can readily be removed from ashes by leaching. 

 When the required amount of potash is withheld the plants are not vig- 

 orous if all of the potash is removed from the soil the plant soon dies of 



