No. 4.] CHEMICAL AND FARM MANURES. 173 



The paper had something to say in regard to the avail- 

 ability of phosphoric acid in bone meal, as compared with 

 basic slag and other materials. You will remember that I 

 said each plot in this series received bone meal at the rate 

 of six hundred pounds to the acre continually since 1884. 

 That is a long time, and in all that time this field has not 

 had one particle of manure of any other kind than bone 

 meal and the two potash salts. I claim that on that soil the 

 results show that bone meal is apparently a useful form of 

 phosphoric acid as well as of nitrogen. I told you what the 

 crop of corn was this year ; over thirty tons to the acre of 

 corn for the silo. Other crops this year and in recent years 

 have been entirely satisfactor3^ We got on these plots 

 yields of clover hay at the rate of three tons and more to 

 the acre ; yields of potatoes at the rate of two hundred and 

 fifty to three hundred bushels per acre ; we got satisfactory 

 ^delds of beets, and, indeed, of all the common farm crops, 

 — and that while we have depended wholly for this long 

 series of years upon bone meal as the source of phosphoric 

 acid and as a source of nitrogen. 



In general, however, I would agree entirely with the 

 position of the paper concerning the relative availability of 

 the different materials which the farmer can purchase for 

 supplying phosphoric acid. 



One other phase of the subject : the materials which fur- 

 nish nitrogen. Our experiments at Amherst have continually 

 been carried out on such systems as to render the hints very 

 suggestive and valuable. AVe have one set of plots where 

 we have for a long series of years, about sixteen years, been 

 using barn-yard manure on one plot as a source of nitro- 

 gen, sulfate of ammonia on several plots, nitrate of soda on 

 others, dry blood on others, and we have in our results in 

 general entirely confirmed the position of the speaker of the 

 morning. ^Ye find the nitrate of soda the best for all crops. 

 We generally find the dry blood next, rather than the sul- 

 fate of ammonia. We find if we use lime in connection with 

 sulfate of ammonia it acts better ; but used in connection 

 with lime it hardly equals the dry blood on our soil, as a rule. 



Doctor AVheeler. Are you sure the dry blood did not 

 contain large quantities of phosphoric acid? 



