Soil thermal response under plastic covers II. Effect of transparent polyethylene at different depths

Enrique Misle A.1 y Aldo Norero Sch.2

During November of 1996, an experiment was carried out at the Universidad Católica del Maule, Talca (35º26’ S lat, 71º26’ W long.) in a Haplanthrepts soil, to determine the soil thermal response under a transparent polyethylene cover (50 m ) at 1, 3, 7 and 15 cm depth, as well as the transversal thermal response (phases 2, 3 and 5). In phases 1 and 4, the effect of four plastic covers on the soil temperature at 7cm depth was informed in a previous paper. Tukey’s test was applied (p < 0.05) to the thermal amplitude in order to verify the reliability of the results. Its value increased about 10°C up to 7 cm depth, showing that it is possible to solarize at this latitude, with a mean temperature of 36°C at 7 cm depth, and with possibly lethal maximums at depths of 7 to 15 cm after 15 days treatment. Phase 5 revealed that there is a thermal decrease toward the borders of the film cover, showing a central area of 20-30 cm where the temperature is uniform. The information obtained is useful to verify a model that describes the thermal conduct of soil under a plastic cover.

Keywords: soil temperature, mulch.
1 Universidad Católica del Maule, Facultad de Ciencias Agrarias y Forestales, Escuela de Agronomía, Casilla 278, Curicó, Chile. E-mail: emisle@hualo.ucm.cl
2 Pontificia Universidad Católica de Chile, Facultad de Agronomía e Ingeniería Forestal, Escuela de Agronomía, Casilla 306, Correo 22, Santiago, Chile.