NATURAL MANURE. 25 



"Assuming," suiil tin- Doctor, who is font! of an argument, 

 " that tho above ^talriiu'iil is triu-, let us look al tlif fads. An 

 acre of soil, 12 inches deep, would weigh about 1,G0U Ions; and if, 

 as the writer quoted by the Deacon states, the soil contains 4 ozs. 

 of potash in every 100 ll)s. of soil, it follows that an acre of soil, 

 12 inches deep, contains ^,000 lbs. of potash. Now, potatoes con- 

 tain about 20 per cent of diy matter, and this dry matter con- 

 tains, say, 4 per cent of ash, half of which is potash. It follows, 

 therefore, that 250 bushels of potatoes contain about 60 lbs. of 

 potash. If we reckon that the tops contain 20 lbs. more, or 80 

 lbs. in all, it follows that tho acre of soil contains potash enough 

 to grow an annu<;l crop of 2oO bushels of potatoes per acre for one 

 hundred years." 



"I know farmers," i^auX Charley, "who do not get over 50 

 bushels of potatoes per acre, and in that case the potash would 

 last five hundred years, as the weeds grown with the crop are left 

 on the land, and do not, according to the Deacon, exhaust the 

 soil." 



" Good for you, Charley," said the Doctor. " Now let us see 

 about the phosphoric acid, of which the soil, according to the 

 above statement, contains only half as much as it contains of pot- 

 ash, or 4,000 lbs. per acre. 



" A crop of wheat of 30 bushels per acre," continued the Doc- 

 tor, " contains in the grain about 26 lbs. of asli, and we will say 

 that half of this ash is p'.iosphoric acid, or 13 lbs. Allowing that 

 the straw, chaff, etc., contain 7 lbs. more, we remove from the soil 

 in a crop of wheat of 30 bushels per acre, 20 lbs. of phosphoric 

 acid, and so, according to the above estimate, an acre of soil con- 

 tains phosphoric aci:! to produce annually a crop of wheat and 

 straw of 30 bushels per acre for two hundred years. 



" The writer of the paragraph quoted by the Deacon," continued 

 the Doctor, " selected the crops and elements best suited to his 

 purpose, and yet, according to his owti estimate, there is sufficient 

 potash and phosplioric arid in the first 12 inches of the soil to 

 enable us to raise unusually large crops until the nevt Centennial 

 in 1976. 



" But let us take another view of the subject," continued the 

 Doctor. " No intelligent farmer removes all the potatoes and 

 tops, all the wheat, straw, and chaff, or all the corn and stalks from 

 his farm. According to Dr. S disbnry, a crop of com of 75 bush- 

 els per acre removes from the soil 600 lbs. of ash, but the (/rain 

 contains only 46 lbs. The other oo4 lbs. is contained in the stalks, 

 etc., all of which are usually retained on the farm. It follows 

 2 



