K. Weaich et al., A COMPRESSION SUCTION TEMPERATURE (CST) CELL FOR SIMULATING THE PHYSICAL-ENVIRONMENT OF PREEMERGENT SEEDLINGS, Agronomy journal, 86(1), 1994, pp. 212-216
Field investigations of the influence of soil physical conditions on s
eedling emergence are hampered by a lack of control and reproducibilit
y of the physical variables. Controlled environment studies frequently
fail to adequately simulate field conditions and seldom permit invest
igation of interactive physical conditions. In this paper, we describe
a compression-suction-temperature (CST) cell designed to enable inves
tigation of the response of preemergent seedlings to various strength
and temperature regimes under unsaturated conditions. The cells allow
independent control of soil strength, temperature, and matric potentia
l. Suction within the CST cells is controlled by a hanging water colum
n, soil strength by application of a uniaxial load, and soil temperatu
re by a combination of heating and cooling of the upper and lower cell
boundaries. Shoot growth in.six cells was uniform, reflecting the min
imal temperature discrepancies between cells. Temperature profiles typ
ical of those experienced in the field were reproduced in the cells. M
aize (Zea mays L.) shoot growth was responsive to temperature, with ma
ximum elongation rates occurring at a constant temperature of 31.5-deg
rees-C. Application of 80 kPa of pressure (estimated shear strength of
42.0 kPa) to the seedbed stopped shoot growth, demonstrating the cell
's capacity to alter the strength environment of the preemergent seedl
ing.