82 MASSACHUSETTS AGKICULTUEE. 



From the able discussion of Prof. Johnson on the Valuation 

 of Manures, I am enabled to compare the manurial value of 

 our corn-crop with that of commercial fertilizers. In the re- 

 port of the Connecticut Board of Agriculture for 1868, Prof. 

 Johnson computes the present market-cost of the commer- 

 cially valuable elements of standard manures as four cents a 

 pound for potash, 12|- cents for phosphoric acid, soluble in 

 water, and 17 cents per pound for nitrogen. To reduce these 

 gold prices to currency at the present time, we must increase 

 them 15 per cent. 



Dr. Nichols, in his lecture before the Board of Agriculture 

 in 1871, reckoned the soluble phosphoric acid at 16 cents a 

 pound and nitrogen 28 cents a pound. If we calculate the 

 value of nitrogen from the present price of nitrate of soda, 

 the cheapest source of supply : we have, cost of nitrate of 

 soda, four cents gold, equal to about 41^ cents currency. The 

 commercial article is giiaranteed 94 per cent. This makes the 

 value of the nitrogen about 29 cents a pound, as pure nitrate 

 of soda contains 16.4 per cent, of nitrogen. In a similar way 

 it is easy for any one to verify the cost of these chemicals by 

 referring to the prices-current in our newspapers. 



Applying Prof. Johnson's prices to our results, as it is well 

 to be on the safe side in calculating values, we have, — 



76.7 lbs. potash, at 4 cts. per lb., $3 06 



76 lbs. phosphoric acid, at 12| cts. per lb., 9 54 



129. G lbs. nitrogen, at 17 cts per lb., 22 03 



Total value in gold, |34 63 



Add 15 per cent, for currency, 5 19 



f39 82 



This sum of about forty dollars can be considered as the 

 value of the manure removed in our crop. From this fact we 

 further obtain that when seven cords of manure are applied to 

 23roduce a crop of eighty-one bushels of Indian corn, about 

 |5.60 per cord value of manure should be charged to the crop. 

 And further, when eighty-one bushels of corn are produced 

 from one acre of land, about forty dollars' worth of fertility 

 is removed from that soil, without reference to the quantity of 

 manure applied. Again, each bushel of grain removes about 

 28.4 cents' worth of fertility, and each ton of fodder about $4. 62. 



