1J)()8.] PUBLIC DOCUMENT — No. 33. 127 



Up to the time Avhen onions were introduced a.s a crop 

 on this field, the leading" conclusions drawn from the experi- 

 ments were the following : — 



1. The phosphatic slag has apparently furnished phos- 

 phoric acid in an exceedingly available form, tlie yield on 

 the plot receiving the slag being almost C(j[ual to that on the 

 dissolved bone-black. 



2. The Florida soft phosphate has given the lowest yields 

 of any plot receiving phosphoric acid. 



3. Steamed bone meal appears to be inferior in availa- 

 bility to raw bone meal. 



For last j^ear the phosphates giving the largest yields of 

 sound onions, mentioned in the order of their rank, were : 

 raw bone, phosphatic slag. South Carolina rock phosphate, 

 apatite, dissolved bone meal, and dissolved bone-black. All 

 others gave yields under 200 bushels to the acre. 



Examination of the table shows that the results are in 

 o-eneral similar to those of last year : the differences, how- 

 ever, are much greater and the apatite and South Carolina 

 rock phosphate take a relatively much lower rank. The 

 dissolved bone meal gives the largest crop ; raw bone ranks 

 next ; while the phosphatic slag stands next in order, with 

 steamed bone meal not far behind. 



The proper ripening of the onion crop, as shown by this 

 as well as other of our experiments, appears to be dependent 

 in very large measure upon the presence of a liberal supply 

 of highly available phosphoric acid. It appears very doubt- 

 ful, therefore, whether it is likely ever to prove expedient 

 to de]i)end upon natural rock phosphates or untreated bone 

 as a source of phosphoric acid for this crop. 



VII. — Soil Tests. 

 During the past season we have conducted three soil 

 tests, — two upon our own grounds, both in continuation 

 of previous work upon the same fields, and one on the 

 farm of A. M. Ljauan of Montague. In these experiments 

 the fertilizers are used in accordance with the co-operative 

 plan for soil tests adopted in Washington in ]<S89. Each 

 plot receives annualh' the same kinds of fertilizers, and 



