NOTES AND ABSTRACTS, 6ll 



NOTES AND ABSTRACTS. 



Acid-tolerant Crops for Acid Soils. By F. V. Coville {U.S. A, 

 Hort. Soc, Illinois, Trans. 1913, pp. 184-196). — This is a study in 

 the adaptability of certain crops to acid soils. In the pine barrens 

 of New Jersey, which are a v/ilderness of soil acidity, blueberry plants 

 grow with the greatest luxuriance and bear fruit in prodigious 

 abundance. In the early experiments with blueberries it was found 

 that these plants grev/ successfully in certain acid soils composed 

 chiefly of partially-rotted oak leaves. When, however, some five- 

 year-old oak leaf-mould was substituted for the partially-rotted oak 

 leaves the growth of the blueberries dwindled almost to nothing. 

 Further study of the decaying leaves of various trees disclosed the 

 facts that when freshly fallen they are exceedingly acid, that as decay 

 proceeds this acidity lessens and then disappears, and that, finally, 

 in the black leaf-mould stage the chemical reaction becomes alkaline. 

 As showing the acidity of freshly-fallen leaves it is estimated that a 

 compact layer 6 inches in depth, estimated to weigh when dry 500,000 

 lb. an acre, would require from 14 to 25 tons of ground limestone 

 an acre to neutralize its acidity, while rye, red clover, alfalfa, and 

 cow-peas, in the fresh state in which they are ploughed under when 

 used for green-manuring purposes, would require from 9 to 13 tons. 

 The rate at which different kinds of leaves pass from the acid to the 

 alkaline stage varies very much, maple taking in some cases only a 

 year, while oak leaves take several, but the rate for green-manuring 

 plants has not yet been determined. 



As nitrifying bacteria do not thrive in acid media, the way in 

 which plants growing in acid soils obtain their nitrogen is an interesting 

 problem. The blueberry bears upon its roots a fungus the threads 

 of which penetrate the living interior of the root tissue. While the 

 experimental results cannot as yet be regarded as furnishing an 

 absolute proof, the evidence strongly indicates that the fungus takes 

 up organic nitrogen from the abundant supply existing in the peat, 

 and delivers it to the plant in some available form. These myccrrhizal 

 fungi exist on the roots of many wild plants on the peat formation. 



Between the two extremes of acid-loving plants and those requiring 

 alkahnity, such as alfalfa and red clover, there are fortunately a 

 certain number of agricultural plants which may be described as acid- 

 tolerant, and they are said to include the strawberry, blackberry, and 

 American red raspberry among fruits, the sweet potato and carrot 

 among roots, and rye, buckwheat, and millet among grains, while 



