REPORT OF THE DEPARTMENT OF 

 CHEMISTRY. 



STUDIES IN PLANT NUTRITION: I* 



W. H. JORDAN. 



SUMMARY. 



(i) Three questions have been studied by growing plants in a 

 forcing house in artificial soils under varying conditions of plant 

 food supply, viz.: 



(a) The relative availability to certain species of plants of 

 phosphoric acid in various combinations, acid phosphate, a 

 finely ground raw phosphate (floats), Thomas slag, dehydrated 

 Redonda phosphate and bone meal; (b) the effect of fineness 

 of division upon the availability of a ground raw phosphate; 

 (c) the fertilizing value of an iron ore waste. 



(2) The results reached show that certain species of plants 

 possess a greatly unlike ability to acquire phosphoric acid from 

 given sources. The cruciferous plants, cabbage and rape, 

 utilized freely the phosphoric acid from ground Florida rock 

 (floats) while with the graminaceous plants, barley, millet and 

 oats, this form of phosphoric acid had small availability, if any. 



(3) Taking the several species of plants as a whole, the acid 

 phosphate proved to be more efficient in the production of plant 

 substance than any other source of phosphoric acid, although it 

 showed no great superiority over Thomas slag. The phosphoric 

 acid in the dehydrated Redonda phosphate, though less available 

 than in the two forms mentioned, proved to be much more avail- 

 able than in the floats. 



(4) Crops were grown during two seasons with the use of 

 ground Florida rock and ground bone, the former varying in 

 fineness from that which would pass through a sieve 60 meshes 

 to the inch to " floats," the bone meal ranging from 60 mesh 

 material to " fine," the latter being a grade finer than that which 

 would pass through a bolting cloth. With three successive crops 

 of rape grown after one application of the phosphates, the effect 

 of fineness was not marked, but with the peas, barley and rape 

 grown in 1903-4 on an improved artificial soil the availability 

 of phosphoric acid in the Florida rock to all three crops, meas- 



* Reprint of Bulletin No. 358, February, 1913. 



I[23S] 



