VIEW ARTICLE

Techniques

An Environmental Cell to Control Simultaneously the Matric Potential and Gas Quality in Soil. H. T. Wilkinson, Assistant professor of plant pathology, Department of Plant Pathology, University of Illinois, Urbana 61801; formerly, post-doctoral research associate, Department of Plant Pathology, Washington State University, Pullman; Phytopathology 76:1018-1020. Accepted for publication 23 April 1986. Copyright 1986 The American Phytopathological Society. DOI: 10.1094/Phyto-76-1018.

A method is described for simultaneous control of matric potential, gas quality, and temperature in thin (2.5 cm) layers of soil. The apparatus permits easy sampling of the soil and soil biotica. The matric potential can be controlled between 0 bars (saturation) and approximately -1 bar; gas quality can be varied to include a single pure gas (e.g., 100% O₂) or any defined mixture of gases. The system uses low gas pressures (≤ 1 bar) to control the matric potential and to circulate gas, thus preventing stagnation of the soil atmosphere. Once equilibrated, the cell can be maintained for weeks without drying of the soil. Matric potentials can be adjusted while the system is operative, thereby allowing studies with soil under controlled wetting or drying. Repeatable soil moisture characteristic curves can be achieved and gas infiltration in emptied soil pores occurs within minutes. In addition to control of matric potential and gas quality in the soil, concurrent temperature control and illumination of the soil surface are possible by placing the cells in controlled environmental chambers.