COMPARISON OF MANURES. 213 



to contain .7 per cent of nitrogen, .4 of phosphoric acid, and .84 

 of potash. The manure was applied at the rate of ten tons 

 to the acre, which quantity would contain about 150 pounds 

 of nitrogen, 80 of phosphoric acid, and 160 of potash. These 

 amounts of the three nutrients would cost, in a commercial 

 fertilizer, at the same rates per pound as in the other calcula- 

 tions whose results have been given, about $40 ; but this ten 

 tons of manure did not begin to cost so much, — it was the 

 waste of the animals producing a revenue by their milk or 

 growth or work. It did undoubtedly cost something, but I think 

 it is safe to say not over $1.50 a ton, or half as much as the horse 

 manure, of which an account has been given above. This would 

 make the plant food in it cost less than half as much as in that 

 manure, and much less than in commercial fertilizers. 



It may seem to many that thus far I have spoken onlj' unfavor- 

 ably' of the use of commercial fertilizers ; but I would not wish to 

 leave 3'ou with the impression on your minds that I regard them 

 with disfavor. On the contrary', I do not believe we could get 

 along without them in general crop growing ; and I see no reason 

 why, if the}' are judiciously used, they should not do as much for 

 horticulture as they are doing for agriculture. If the farmer 

 succeeds better in getting profitable returns from an investment in 

 a certain quantity of nitrogen, phosphoric acid, and potash in a 

 superphosphate than the horticulturist does, it may be because the 

 latter has not learned by experience, as the former has, how to get 

 such returns ; and as long as he can procure animal manures by 

 any sort of management he will continue to use them rather than 

 get out of the ruts and learn how to use something else in place 

 of them. So far as the humus is concerned, on whose apparent 

 usefulness I have dwelt so long, its due proportion in the soil can 

 be maintained by green manuring, and without getting or making 

 much stable manure ; or by spreading over the uplands some of 

 the contents of the muck deposits that are to be found on so many 

 farms. 



In order, however, to enable these commercial manures to com- 

 pete with the cheaper plant food in animal manures, they must be 

 bought at such rates, and in such ways, as to reduce the cost of 

 the plant food they contain to as low a point as possible. A com- 

 parison of the cost of plant food in mixed fertilizers, such as 

 superpliosphate and special manures, with cash prices for precisely 

 the same quality in the raw materials used by the manufacturers 



