CANADIAN FIELD EXPERIMENTS 507 



grain on all the plots of wheat, barley, and oats. The young clover plants 

 made rapid growth, and by the middle of October there was a thick mat of 

 foliage varying in height and density on the different plots, which was plowed 

 under. No barnyard manure was applied on plots i and 2 in each series from 

 1898 to 1905. 



"In 1900 all the fertilizers on all the plots were discontinued, and from then 

 to 1905 the same crops were grown on all these plots from year to year without 

 fertilizers, sowing clover with the grain each season. In this way some infor- 

 mation has been gained as to the value of clover as a collector of plant food, and 

 also as to the unexhausted values of the different fertilizers which had been used 

 on these plots since the experiments were begun. In 1905-6-7 all the fertilizers 

 were again used as in 1898." 



The corn plots and root plots were fertilized somewhat differ- 

 ently from the others, and the corn was cut green and weighed in 

 the fresh condition. The results with wheat, oats, and barley are 

 of more general interest, and the most significant data from these 

 crops are recorded in Table 106, in which all dated intervals are 

 inclusive. 



In the author's opinion, we must question the conclusion of Doc- 

 tor Saunders that nonacidulated mineral phosphate is of no value 

 as a fertilizer. There are at least two important points to be con- 

 sidered before drawing any final conclusion : First, does the land 

 need phosphorus? Or, in other words, is phosphorus the limiting 

 factor? Sandy loam soils are more likely to be deficient in either 

 nitrogen or potassium than in phosphorus. 1 Second, was any 

 adequate means provided in the system of farming for liberating 

 the phosphorus from the raw phosphate? 



From Table 106 we see that the raw phosphate used alone pro- 

 duced practically no increase on wheat, oats, or barley, but this is 

 also true as regards fine-ground bone during the first ten years, 



1 Since the above was written, Professor Frank T. Shutt, Chief Chemist of the 

 Dominion Experimental Farms, has kindly furnished the author unpublished 

 analytical data from samples of soil collected in 1898, which show that 2 million 

 pounds of surface soil contained, for plot 3 in the oats series, 2130 pounds of nitro- 

 gen, 1950 pounds of acid-soluble phosphorus, and 3160 pounds of acid-soluble 

 potassium ; while the corresponding figures for plot 3 of the barley series were 

 2600, 1850, and 2990, and for the wheat series, 2120, 1470, and 3240 pounds. 

 Compare the following significant figures : 



NITROGEN PHOSPHORUS POTASSIUM 



Oats 9700 1600 6800 



Soil 2130 1950 3160 



