STUDIES OF PLANT GROWTH IN HEATED SOIL 



GUY WEST \MLSON 

 (Laboratories of thc New York Botanical Garden) 



(WITH PLATES 3-5) 



Introduction. The problem of the effect of heat on soils is 

 one of interest alike to the chemist and the botanist. The effect of 

 heat on the soil elements themselves forms a prohfic field for inves- 

 tigation, while the resultant changes in the growth of plants pre- 

 sent a no less interesting series of problems. In a recent paper 

 Seaver and Clark^ have discussed some of the problems in each of 

 these fields and presented a review of the hterature of the siibject 

 to date. As the present paper represents work done in the same 

 laboratory on the same hne of problems, and foUowing the same 

 general methods of these workers, no further discussion of the 

 previous work on the siibject appears to be necessary, except in 

 connection with the analysis of the results of the experiments de- 

 tailed here. 



Experimental, General plan. In all of the experiments de- 

 scribed below the soil was the ordinary unfertilized soil of Bronx 

 Park. While this is not rieh in plant food and, from many stand- 

 points, is not so satisfactory for such work as a richer agricultural 

 soil, the results obtained from percolation experiments corresponded 

 with those described by Seaver and Clark, except that the lighter 

 color of the percolates indicated a lower percentage of soluble 

 matter. For each experiment twelve f our-inch pots were filled with 

 sifted soil and divided into groups of three each. One group was 

 used as the check and the others heated in a dry oven for two hours 

 at temperatures of 95°, 135°, and 175° C, respectively. From 

 each of these groups one pot was used for percolation and the others 

 planted with the various crops to be grown, ten seeds being sown in 



1 Seaver, Fred J., and Clark, E. D. : Biochemical studies on soils subjected 

 to dry heat, Biochem. Bull., i : 413-427 (pl. 7) ; 1912. 



202 



