278 AMERICAN AGRICULTURE. 



tity of couch-grass and bent. There is no doubt, therefore, 

 that the quality of Gurneyized grass will be found in prac- 

 tice equal, if not superior, to that of ordinary growth. 



It was thought that the action of fibrous covering was 

 occasioned by retarding evaporation, and shading the soil 

 during the unusually dry season. This, however, is not the 

 case ; the same proportional increase of vegetation has gone 

 on since the wet weather set in, and still continues. Mr. 

 Gurney stated at the last meeting that he has found fibrous 

 covering, in a late experiment during the wet weather, had 

 brought up the eaver and clover in a barley arish, in which 

 the seeds had failed from the dry season." The kind of soil, 

 and the circumstances attending the application are not 

 stated, but I infer from the product on the ground, that ft 

 was a very thin and light, and probably a dry soil. 



The observation has been frequently made in this country, 

 that many half-cleared pastures, where the trees and brush 

 had been prostrated and partially burnt, leaving a heavy 

 covering of old logs and dead branches, gave a much larger 

 supply of feed than such as had been entirely cleared. All 

 the facts and attending circumstances, however, have not 

 been given with sufficient particularity to draw any well- 

 settled conclusions ; yet from the generality of the remark 

 by observing and careful men, there is undoubtedly some 

 weight due to it. The same effect has been often claimed 

 from certain stony fields, which apparently give much larger 

 returns than others from which the stones had been removed. 



If the results are as have been inferred, after deducting 

 something for what observation or science may possibly not 

 yet have detected, I would ascribe them to two causes. 1. 

 The gradual decomposition of the vegetable covering or 

 stone, as either may have occupied the ground, and the di- 

 rect food which they thus yield to the crop ; and 2. the 

 greater and more prolonged deposit of dew, which is going 

 forward through most of the twenty-four hours of every 

 day on large portions of the field. (Does the influence of 

 the shade and moisture promote an unusual deposite of am- 

 monia, nitric acid, or any of the fertilizing gases ?) I am 

 inclined to think nitric acid is thus formed in considerable 

 quantities, and especially where there is an appreciable 

 quantity of lime in the soil. Both M. Longchamp, and Dr. 

 John Davy assert, " that the presence of azotized matter is 

 not essential for the generation of nitric acid or nitrous salts, 

 but that the oxygen and azote of the atmosphere when con- 



