BY E. H. GURNEY. 15 



regions where it is the habit to maintain on the surface 

 of orchards and vineyards ^during the dry, hot summers 

 a thick mulch of well-tilled* soil, thus preventing loss of 

 water and evaporation. In the course of years this surface 

 soil becomes so badly depleted of humus that tilth 

 becomes impossible, the soil becoming light-coloured and 

 compacted, while the loss of nitrogen is indicated by the 

 small size of the fruit. Similar losses are of course sustained 

 in the practice of bare summer-fallow, which at one time 

 was almost universal in portions of the arid region. The 

 complete extirpation of weed growth thus brought about, 

 at first considered an unmixed benefit, has ultimately, had 

 to be made up for by the practice of green manuring — • 

 since in the arid region the use of stable manure encounters 

 many difficulties." 



In analyses of Canadian prairie soils by Shutt*, the 

 extreme figures, mentioned for this particular type of soil, were 

 for organic and volatile matter 5.54 per cent, and 26.29 per 

 cent., and for nitrogen 0.134 per cent, and 1.005 per cent., 

 which indicate the very high content of organic matter in 

 these soils. The following extract from this paper is given 

 to point out that consideration of the organic matter even 

 in these soils is deemed necessary : — '' While expressing 

 this very favourable opinion of the Canadian Western 

 Prairie soils it must, at the same time, be pointed out that 

 exclusive grain growing and fallowing, now so common, 

 must give place to more rational farming methods if the 

 soil is to be maintained at its present high standard of 

 productiveness. For the continued supply of available plant 

 food, for the conservation of the necessary soil moisture 

 and for the preservation of good tilth, the store of humus 

 with its concomitant nitrogen must not be allowed to become 

 depleted, and to this end the means are the adoption of a 

 rotation, more particularly one containing a legume, and 

 the keeping of live stock." 



And Howellf in connection with the Victorian wheat 

 soils, writes : — 



*Western Prairie Soils. F. G. Shutt, Bull. No. 6, Dept. Agriculture, 

 Canada, 1910. 

 tOp. cit. 



