Ta. Tindall et al., AGRONOMIC MODIFICATIONS OF A DRYLAND WINTER-WHEAT ENVIRONMENT RESULTING FROM GRAPHITE-NITROGEN APPLICATION TO SNOWPACK, Soil science, 155(6), 1993, pp. 417-424
Graphite, in an aqueous nitrogen (N) suspension of urea ammonium nitra
te (UAN), was applied to snow covering dryland winter wheat in either
February or March to determine impacts on wheat yield, soil temperatur
e, available soil moisture, and N movement in soil. Field experiments
were established on soils with slopes of 1-2% in both the Pocatello Va
lley and Soda Springs areas of southern Idaho. Snow depths ranged from
40-65 cm at treatment application. Soil water content was determined
with a neutron probe. Thermocouples were used to measure soil temperat
ure in each plot following snowmelt from control plots. Soil water dif
ferences were observed between the graphite treatment and the control
to a soil depth of 90 cm in the spring. Soil temperature fluctuation f
ollowing snowmelt was greater where graphite influenced snow melt. The
re was a tendency for higher initial soil temperatures (above 0-degree
s-C) with the graphite treatments compared with the control. These hig
her temperatures were observed for over 20 days and to a depth of 20 c
m. Increased wheat yields were observed with graphite-N applications o
ver snow compared with similar fall or spring N application treatments
. These higher yields were likely the result of increased soil tempera
ture and soil water content as a function of controlled (pulsed) snow-
melting with graphite.