648 PROCEEDINGS OF SECTION K. 



Manuring of any description was quite ineffective in improving 

 the growth of flax, or in destroying the fungus, nor did treatment 

 of the soil with any of the usual fungicides produce any better re- 

 sults. There appears to be no way to rid the soil of the parasite, 

 as the fungus lives in the soil for many years without any flax-crop 

 to feed upon. This fungus does not appear to attack any other 

 crop. 



The remedies suggested are treatment of the seed with sub- 

 stances such as formalin, and a five years' rotation of flax with 

 wheat, hay, pasture, and maize. 



Bclley has also shown (Press Bulletin, No. 33, North Dakota 

 Agricultural Experimental Station, October, 1909), that the 

 deterioration of wheat-lands is brought about by three or four 

 parasitic fungi (in a later communication he gives the number as 

 at least five), whose growth is encouraged by the practice of con- 

 tinuous cropping of the land with wheat, and which are propa- 

 gated and attack the wheat plant in exactly the same way as flax 

 is attacked by Fusarium lini. 



Similar instances of loss of crop-producing power have been long 

 familiar, that of clover sickness being one of the earliest to be recog- 

 nised. Peas, beans, turnips, and cauliflowers are all subject to 

 parasitic fungi which grow on the buried portions of diseased plants 

 and communicate the disease to healthy plants. The same is also 

 true of many of the fungus diseases which affect the potato, tomato, 

 &c. 



In all these cases we have toxic conditions which are quite dis- 

 tinct from the infertile condition brought about by soil-exhaustion, 

 conditions which are not dependent upon the richness or poverty of 

 the soil, and which no amount of manuring in the ordinary sense 

 will remedy. Indeed, when we consider the large stores of plant 

 food in average, and even in poor, soils, the comparatively small 

 proportion removed by even the most exhausting crop, and the 

 fact that this store of plant food is being constantly rendered 

 available, it becomes difl&cult to realize that a few years' cropping 

 can effect such a complete removal of plant food as we must assume 

 to take place if the soil is exhausted in the manner usually recog- 

 nised. 



As a matter of fact, analyses of European soils go to show that 

 under continuous cultivation, there is little or no difference in the 

 mineral content of the soil. In short, the inferior crop-producing 

 power of a soil after repeated cropping is due to other and more ob- 

 scure causes than the simple depletion of the soil in plant food. 



Infertility often due to Bad Husbandry. 



It is, indeed, open to doubt whether such a thing exists as an 

 absolutely infertile soil, that is, one which will not give satisfac- 

 tory results under proper treatment. Plants, we know, can be 



