128 FERTILIZERS ON SANDY SOIL — SMITH. 



is a sul)ject for investio-atiun, They should be in a very avail- 

 able condition for the plant. Manure, when applied to such soils, 

 would increase their retentive power for water, and by its decay 

 in the soil might improve their physical and chemical properties 

 immensely. 



PART III. 



What does our Soil Require ? 



The problems that presented themselves to us on taking pos- 

 session of the farm for the School in the late fall of 1888 con- 

 tained among others the following questions : — 



What plant foods are there in the soil ? 



How abundant, and how accessible to the plant ? 



Is the difference in demand made by the different crops shown 

 by application of fertilizers ? 



In order to answer these questions, some experiments were un- 

 dertaken as soon as we obtained possession of the farm. These 

 were confined to Nitrogen, Phosphorus and Potassium. In each 

 application of fertilizer a slight excess over what it was thought 

 would be required for the plant was used. The same amount of 

 each was used when used together. Forty-two separate trials 

 were made during the past two years, the results of which are 

 recorded in this paper. Instead of giving the amount of the dif- 

 ferent yields, I have reduced the increased yield to per cent, of 

 increase over the unmanured plots. This enables us to compare 

 the results one with another much more readily. 



The table gives the year, the crop, the fertilizer applied, and 

 the per cent, increase. In each set of experiments the plots were 

 treated exactly alike in every other respect. It will be observed 

 that each ingredient increased the yield when applied alone, 

 that as a rule, when two were applied together the inerease was 

 greater than when a single ingredient was applied, but not 

 double that of either, finally, that when three were applied, the 

 increase was often over three times that caused by a single 

 ingredient. The results from manure on potatoes are worthy of 

 notice. 



