PHOSPHORUS, ITS SOURCES AND USB IN PLANT FEEDING 63 



will, therefore, have a larger percentage of phosphoric acid than raw bone 

 meal, but far less nitrogen ; and if the phosphoric acid is what we are after, 

 the steamed bone is better than the raw, and the absence of nitrogen should 

 make it cheaper. But it must be remembered that the phosphoric acid is not 

 in an immediately soluble condition, though through the rapid decay of the 

 bone it may soon become so. 



The Florida soft phosphates are not available ^n the manufcture of 

 acid phosphates, and hence, many efforts have been made to get farmers to 

 use them in an untreated state. An article called "Natural Plant Food," 

 was some time ago largely advertised. This consisted almost entirely of the 

 Florida soft phosphates, with some insoluble potash, such as is found in the 

 green sand marl of New Jersey. It has been found that on a soil abounding 

 in humus, and in an acid condition, the pulverized phosphatic rock sold under 

 the name of "floats" acts very well, especially on clover and other legumes, 

 but that liming the soil, which helps the success of the clover, renders the 

 phosphate less effective. In some stations the insoluble phosphoric acid is 

 given no value whatever, while at other stations it is rated at 2 cts. per pound, 

 with the soluble at four and a half cents. What we wish particularly to 

 impress upon the farmer, is the fact that phosphoric acid from any source is 

 identically the same thing, and the only question that concerns him is what 

 percentage of the article is in a soluble state, for it is this which is to give him 

 immediate results in the crop. 



BONE MEAL AS A SOURCE OF PHOSPHORIC ACID. 



We have stated that phosphoric acid is one and the same thing no matter 

 from what source it comes, and that the only thing to regard is the percentage 

 of soluble acid. On this point the investigations of the Massachusetts Exper- 

 iment Station show the following conclusions: 



1. The superior VALUE which has hitherto been accorded to undis- 

 solved bone meal as a fertilizer is due solely to the nitrogen it contains. 



2. Undissolved bone meal, as a phosphate fertilizer, is no more valuable 

 than the raw mineral phosphates (floats). 



3. Hereafter it must be classed with the latter, rather than with the 

 high grade phosphates containing available phosphoric acid. 



4. As a phosphate fertilizer it yields no better results than the mineral 

 phosphates, whether tried alone or with superphosphate, on loams or sandy 

 soils, on soils rich or poor in phosphoric acid, whether with grains or with 

 turnips, mustard or other cruciferous plants ; either in the first or second crop. 



5. The various kinds of bone meal show no essential difference in these 

 results. In experiments made by Wagner at Darmstadt, Germany, the phos- 



