56 VERMONT AGRICULTURAL REPORT. 



1. Rock and soil potash. Potash is found in soils as clay, as marl, 

 and in other forms. It is insoluble in water and is available with ex- 

 treme slowness. 



2. Organic potash. Potash is built into vegetable matter during 

 the course of the life of the plant and through its decomposition may 

 become available to the growth of other plants. Cottonseed meal, to- 

 bacco refuse, castor pomace and the like contain considerable propor- 

 tions of this ingredient, which, while insoluble in water, is of use as a 

 fertilizer. 



3. Potash from ashes. When cottonseed hulls, tobacco stems, wood, 

 etc., are burned, the ash residues contain from 5 to 30 or more per 

 cent, of potash, mainly as carbonate. Most of this potash is soluble in 

 water and is an admirable form of this ingredient for fertilizing pur- 

 poses. 



4. Potash from mineral salts. Practically all the potash which 

 enters into the manufacture of commercial fertilizers to-day is de- 

 rived from the German potash salt mines. The saline minerals which 

 are mined in that country are sold either purified or in the crude, but 

 ground, state. The more common salts are the muriate, sulphate, and 

 kainit. All of these salts are soluble in water, and the potash is im- 

 mediately available for plant purposes. 



FUNCTIONS OF POTASH. 



The known functions of this ingredient appear to be three in num- 

 ber. 



1. It seems to be an essential to the formation and transference of 

 starch in plants and thus indirectly affects sugar formation. 



2. It plays an important part in the development of wood structure 

 and of the fleshy portions of the fruit. 



3. It is in part a neutralizer of plant acids. 



1. Starch is formed in the leaves of the plant through the agencies of 

 the sunlight and the chlorophyll or green coloring matter. But starch 

 is insoluble and cannot pass through the plant tissues. In some way 

 not thoroughly understood it becomes sufficiently changed so that it 

 can permeate the cell walls and thus be transferred to and accumulated 

 in fruit, stalk, root, or tuber, where it becomes insoluble again. While 

 the way in which this transference is brought about is not thoroughly 

 comprehended, it is known that potash plays an important part therein 

 and, also, that this ingredient aids in the original formation of the 

 starch. No other constituent seems capable of replacing it in this 

 peculiar and important function. 



When potash is in the form of muriate the accumulation of starch 

 more particularly at some one point, as in the tuber of the potato, seems 

 to be somewhat interfered with. The tendency of chlorin seems to be 

 in the direction of diffusing rather than of concentrating starch. This 

 point has some bearing in the choice of the form of potash for the 

 growth of different crops. Since sugar is probably formed from starch, 

 the relationship of potash to its formation is obvious. 



