146 Food from the Soil 



It is the long-continued course of this green-manuring 

 which has so largely contributed to produce the extra- 

 ordinary fertility of the ' Black earth ' of Russia and 

 the region of Manitoba. And so, too, with the Pampas 

 of South America, a still more interesting example, 

 because the process is going on under our eyes. 



In the winter Captain Head found the ' thistle ' part 

 of this region looking something like a rough turnip- 

 field intermixed with clover, so large and luxuriant were 

 the leaves of the ' thistles ' — really wild artichokes. In 

 the spring, the ' thistle '-leaves had spread, and had 

 overgrown the clover, but still had the appearance of a 

 rough crop of turnips. Less than a month later, how- 

 ever, they had shot up in the most surprising manner, 

 and were in full bloom. They were now ten or eleven 

 feet high, and formed such a close, impenetrable barrier 

 on each side of the track that nothing whatever could 

 be seen in any direction. The growth was so amazingly 

 rapid that an army might easily have been hemmed in 

 unawares by the thick, strong stems. 



Before the end of the summer there was another 

 change. The heads drooped, the leaves faded, the 

 stems turned black and rattled in the breeze until they 

 were blown down by the periodical hurricane, when 

 they quickly rotted away, and the strong luxuriant 

 clover rushed up again. 



The artichoke, as well as its near relation the true 

 thistle, requires a rich soil, and would be an exhaust- 

 ing crop if it were cut and removed, because it takes 

 so much food ; but as the roots penetrate to a great 

 depth, it benefits the clover, and the clover in its turn 

 enriches the soil for the thistles. 



Clover is found, indeed, to be such a beneficial crop 



