Grain Manuring Experiments, 1903-4. 775 



the more active nitrification in our soils, favoured by the difference in 

 climatic conditions. It is a question, however, owing to the much 

 larger crops we are at present able to secure by the application of a 

 purely phosphatic manure, whether the nitrogenous matter of our soils 

 will be sufficient to provide the nitrogen necessary for these larger 

 crops over any lengthy period of time, or whether there will not be a 

 gradual falling off in the yields owing to the exhaustion of this 

 nitrogenous matter. Under our present system of taking a crop 

 once in three years, and devoting the other two to grass and bare 

 fallow, such a contingency is, I think, not probable. There is just the 

 possibility, however, of farmers, owing to the increase obtained from the 

 use of manures, giving up more largely the year of grass, or at least 

 the bare fallow on which they formerly depended for this result, and 

 adopting in places a system of continuous cropping. (The more ex- 

 tensive keeping of sheep will, of course, do away with this state of 

 affairs). There is no doubt that in years of a good rainfall crops are 

 obtainable from the stubble with phosphatic manures for successive 

 jears, as good, or almost as good, as those from the fallow; but should 

 such a system of continuous cropping ever find favor, it will most 

 probably have as its sequence the exhaustion of the soil nitrogen, and 

 the gradual falling off in effective power of our phosphatic manures. 

 Under the three-year system of crop, grass, and fallow, at present 

 pretty general in our drier districts, such an exhaustion of nitrogen 

 is, as I stated, a remote possibility. The average farmer is, perhaps, 

 unaware that the trefoil, clovers, and other leguminous plants that find 

 a place during the year of grass in the natural herbage of the portion 

 of the farm he leaves out, perform a singular and valuable service 

 for him by accumulating in a wonderful way large quantities of 

 atmospheric nitrogen, and leaving them in the ground for the benefit 

 of crops that follow. An examination of such facts will show that a 

 year's results from an experimental field cannot give us all the infor- 

 mation we require in this direction. Experiments must continue on 

 the same field with the same manures over a long series of years, 

 under the conditions of continuous cropping, cropping with an 

 alternate year of fallow, and cropping with the two intervening years 

 of pasture and bare fallow. The effect of a leguminous crop to take 

 the place of the year of grass should also be tested." 



The Effect of Subsoiling. 



The various cultivation tests included in the experiments are 

 not yet in a sufficiently advanced state to admit of discussion. 

 The effect of subsoiling, however, notably in the field of Mr. 

 McPherson, appeared sufficiently marked to justify some reference. 

 Both in the appearance of the growing crop and the actual results 

 obtained in weight of grain and straw, there appears evidence for 

 concluding that a deeper cultivation in the more compact clay soils 

 of the North will result in a considerable improvement in yields. 

 In the case of Mr. Moi^timer, the difference produced by subsoiling 

 was not so pronounced, but the heavier yields on the subsoiled plots 

 than on the adjoining check plots, not similarly treated, suggest 

 that in his case also the deeper cultivation had resulted favourably. 



