178 



Journal of Agricultural Research 



Fig. I.— Typical charts of soil temperatures during the winter season: Records for week ending January 

 12, 1914. A, Tillage with cover crop; D, grass land; C, straw mulch. 





■ I - — ~~T — op I j ■ ' I ; : I i ^~"!~ , ^p.Vr ^ rxr 



fr^, 



^ 





Fig. 2. — Typical charts of soil temperatures during the spring time: Records for week ending April 

 1914. A, Tillage; D, grass laud; C. straw mulch. 



