42 



Similarly the effect of rolling in compacting the 

 soil has resulted in an injury ascribed to decreased 

 aeration 1 and the injury to forests through accumula- 

 tion of vegetable refuse on the soil has been referred 

 to decrease in the ease of renewal of the soil air. 

 Similarly Hesselman 3 ascribes the death of certain pine 

 forests by "swamping", not so much to excess of water 

 as to deficient aeration. He reports that running 

 water, which is well aerated, does not kill the trees 

 even when it stands above the soil surface. Graves 4 

 has assigned to deficient soil aeration a case of root- 

 rot in conifers growing in impervious soil and Elst 

 has described a root-rot disease of rice which he 

 believes due, in part at xeast, to poor soil aeration. 



~~Tl von Seelhorst and Krzymowski,- Jour. Landw. 

 53: 269-278 (1905). 



2. Hartig,- Textbook of diseases of trees, 

 pp. 2 76-278 (1894). 



3. Meddel. Stat. Skogsforsoksanst. 1910 . No. 

 7, pp. 91-125. 



4. Phytopath. 5: 213-217 (1915). 



5. van. der Elst,- Dept. Landb. Kijv. en 

 Handel, Meded Proefstat. Rijst., 104 pp. (1912). 



