370 STATE HORTICULTURAL SOCIETY. 



that vary between widely distant limits, and appear to depend to a high 

 degree on the condition of soil and season. Confusing as were these 

 results, two facts have been established beyond any question of doubt i 

 First, that the plant derives its ash constituents from the soil ; and 

 second, that a certain amount of each of about 13 substances is so 

 absolutely necessary to its development that complete absence of any 

 one of them not only checks but actually prevents growth. Potash^ 

 phosphoric acid and nitrogen in available form are the only three, how- 

 ever, that need consideration, as the other 10 are never wanting in an 

 arable soil, and discussion of them can lead to no practical result. 



Potash, phosphoric acid and available nitrogen — that is, nitrogen 

 in the form nitrate — enter the plant through the roots and from the soil^ 

 and as these substances are intimately connected with the production 

 within the plant of the two great classes of foods on account of which 

 we carry on agriculture, viz., starch and proteids, it is plain that greater 

 quantities of the former in the soil will mean greater production of the 

 latter in the plant; and since cultivated differ from uncultivated plants 

 mainly in being richer in starch and protein, it follows that the re- 

 moval of cultivated crops deprives land of a greater proportion of these 

 valuable mineral constituents than does the gathering and removal of" 

 plants that were the natural growth. Increasing of one's crop, there- 

 fore, means plainly, first increasing of the plant food in the soil ; the 

 one depends upon the other, and to expect continuous and large crops 

 of any kind from land inherited or bought by its cultivator is as reason- 

 able as to expect continued payment of checks on the strength of the 

 deposit that at some former time had been made in a bank. In both 

 cases the drafts upon the available resources, as a means of continued 

 profitable business relations, must be made good ; fertilizer must be put 

 upon the land and money placed in the bank. 



It may, then, be taken for granted that potash, phosphoric acid 

 and nitrates in the soil in certain amounts are necessary to insure satis- 

 factory crops, and that they must be in soluble — that is, available — 

 form to become active. The large quantities of the two former that 

 have been mentioned before as existing in our soils are, however, 

 soluble only to a limited extent, and though certainly valuable, they 

 are not sufficiently and immediately available for the demands of a large 

 crop; for such a one additional and proper fertilizing material must be 

 supplied regularly and intelligently. This necessity is emphasized by 

 the fact that plants absorb the greater share of these mineral matters 

 during the early stages of their growth, and do so in a special and pe- 

 culiar manner. 



This truth has, in fact, a most important bearing upon the whole 

 question of manuring ; for it is plain that if the absorption of the larger 



