DR. MCliOL.^" AJ)l)RE.-.<, 15 



of potash ; -dho, I am certain it will remuVL' 15<> pouiuls; uf phuspliurii; 

 acid. Now these amounts are very hirge and serve to sliow that the 

 potato plant is a great consumer of the two substances, and also it 

 shows that in order to restore our potato fields to their former prod uc- 

 tive condition we must supply phosphatic compounds and substances 

 holding potash in large ([uantities. For six or eight generations, in 

 Kew England, our fathers have been exhausting the soil by removing 

 these agents, in their potato and other crops, and we have nniched a 

 time when the vegetable is starving in our tields for want <»f its proper 

 food. Our farmers have found that new land gives the best crop.s, and 

 this is due to the fact that such fields afford the most potash. But so 

 long as we crop our pastures so unreasonal)ly we cannot resort to new 

 land, as land is not new that has had its potash and phosphatic ele- 

 ments removed by grazing animals. Remember that a potato field 

 which gives but 10(1 bushels to the acre, re((uires at least i()0 pounds 

 of potash, but by allowing the tops to decay upon the field, GO pounds of 

 this is restored to the soil again, as that amount is contained in them. 

 A medium crop of potatoes re(|uires twice as much phosphoric acid 

 as a incdium crop of wheat, so that in two years with wheat, the land 

 is deprived of no more of the agent than it loses in one year with 

 potatoes. 



The subject of the food of plants is so vast and important in it.-- 

 bearings upon agriculture that it cannot l)e properly con.sidered in a 

 single address, and I fear to weary you ])y dwelling upon it longer. 



My aim has been to point out the nature of the materials which 

 plants require, and to impress upon the minds of those who hear me, 

 the great truth that when the farmer has gaineU this knowledge, and 

 also learned the quantity necessary for a given crop, the accumulation 

 and u.se of these materials is as simple as that of supplying raw mate- 

 rials for the manufacture of cloth, boots and shoes, or any other manu- 

 factures. A field in proper condition for culture should contain in 

 ample abundance all the inorganic materials which the intended crop 

 requires, and these materials should be in an a.ssimilable condition, or 

 in other words, they should be in a soluble condition, so that by the 

 aid of water they can be taken up and carried through the plant 

 organism. The proper manures for wheat and corn are the nitrogenized 

 varieties, or tho.se which hold nitrogen, either in the form of ammoni;'. 

 or us nitric acid. These should be conjoined with phosphates and pot- 

 ash in considerable amounts. For potash, phosphates and linie are 

 required ; the latter element, lime, enters largely into the leaves and 

 is an important article of food for the vegetable. Gypsum, or plaster, 

 which holds lime and sulphuric acid, is a valuable manurial agent for 

 potatoes, especially on moist land. T have u.sed it with satisfactory 

 results. Fioots, and also wheat, should be supplied with magnesia, a.s 

 it is found largely, in the form of phosphate, in the ash of these jtlants. 

 But enough has been said to show that each variety of plants demand.^ 

 peculiar kinds of food, and without it is supplied by the ^oil, or through 

 our agency, it is impossible for it to flouri.sh. 



During the past eight years T have been endeavoring to guide the 



