842 
Journal of Agricultural Research 
V6L XXm. No. ri 
moisture and temperature, could be separated and their individual 
influence studied. 
In the field the temperature and moisture experiments were handled 
by sowing at different dates during the fall and spring. Continuous soil- 
and-air temperature records were secured by means of the soil-air thermo¬ 
graph, which was checked each day by electrical resistance thermocouples 
Flo. a.—Graphs showing soil and air temperature for the season of 1921 and percentage of stand of spring 
wheat and corn sown on different dates. A, Com; B, Marquis wheat. The squares of the graph paper 
are filled in for the seedling period of each sowing, as, for instance, August 24 to ao. This represents the 
period during which the environmental factors influenced the development of seedling-blight. To avoid 
confusion the curves for percentage of stand of plants are plotted on the date sown. The distance between 
the solid lines and broken lines showing stand of check and inoculated plots represents the percentage 
of seedling-blight. 
placed immediately adjacent to the soil-thermograph bulb and left undis¬ 
turbed for the duration of the experiment. The instrument bulbs were 
placed in the plots used for the experimental studies at depths of 2 and 4 
inches. Sowings were usually made after a rainy period when the mois¬ 
ture content of the soil was at about 15 per cent, based on water-free soil 
(fig. 2). In some few cases it was necessary to increase the soil-moisture 
