474 



Journal of Agricultural Research 



Vol. VI, No. 13 



no kgm. of soil. Forty of these cans were used in 1914 and 60 in 

 191 5. The upper foot of field soil was worked through a sieve with a 

 5^-inch mesh and then thoroughly tamped in the cans. The soil was in 

 good tilth, and for both seasons the moisture content ranged from 20 

 to 21 per cent (dry basis). It had a moisture equivalent of 24 and a 

 wilting coefficient of 13, as calculated by the formula of Briggs and 

 Shantz.^ 



The cans were provided with metal lids which were sealed with ordi- 

 nary binding tape (PI. LXXII, fig. 4). This was made waterproof by 



V^K J6/A/S JuLi" August September 



Fig. I. — Curves of the evaporation at Garden City, Kans., for the growing period of 1915. 



giving it a heavy coat of varnish after it was in position. Three 2-inch 

 holes equidistant from one another were made near the periphery of 

 each lid to accomodate the plants. The seeds were planted in the cans 

 and the young plants gradually thinned to the desired number. Three 

 corn plants were grown in each can, both in 1914 and 191 5. Six sorghum, 

 plants were grown in each can in 1914, but in 191 5 the number was re- 

 duced to three plants to each can. In order that the plants might be 

 as nearly as possible under the same climatic conditions during the 

 growing season, the seeds of all the plants used were sowed on the same 

 date. These were planted on May 26 in 1914, and on May 22 in 1915. 



1 Briggs, L. J., and Shantz, H. L. The wilting coefficient for different plants and its indirect determina- 

 tion. U. S. Dept. Agr. Bur. Plant Indus. Bui. 230, 83 p., 9 fig., 2 pi. 1912. 



