Effects of rainfall and cover on soil temperatures of an isohyperthermic temperature regime, Panama

• Published in: Geoderma 1988-07, Vol.42 (2), p.129-146
• Main Author: Manrique, L.A.
• Format: Article
• Language: English
• Subjects: CAJANUS CAJAN; CROP RESIDUES; FALLOW SYSTEMS; GRAMINEAS; GRAMINEE; GRASSES; IRRIGA; IRRIGATION; LLUVIA; MANIHOT ESCULENTA; PANAMA; PLUIE; RAIN; RESIDU DE RECOLTE; RESIDUOS DE COSECHAS; RIEGO; SISTEMAS CON BARBECHO; SOIL TEMPERATURE; SYSTEME JACHERE; TEMPERATURA DEL SUELO; TEMPERATURE DU SOL; TEPANAMA
• ISSN: 0016-7061; 1872-6259
• DOI: 10.1016/0016-7061(88)90029-8

Data from an experiment conducted in Santiago, Panama, measuring temperatures at 0-, 10- and 20-cm depths in bare and irrigated-bare plots and in plots covered with natural grass, cassava and Cajanus cajan residues, respectively, were used to analyze spatial and temporal variations of soil temperature in an isohyperthermic environment. Measured temperatures were then used to estimate heat flow and heat balance in the soil during selected periods of the rainy and dry seasons. Measured temperatures were also put into a model to predict soil temperatures. Night temperatures in the rooting zone (0–20 cm) were lower than 25°C for at least 8 hours during the dry season (January–April); day temperatures never rose above 33°C. In the rainy season (May–December), however, night temperatures were higher than 25°C and day temperatures were 1° or 2°C greater than night temperatures. Surface residues effectively lowered temperatures during the dry season but were less effective during the rainy season. Little downward heat flow occurred in the bare plot during the dry season. In contrast, irrigation promoted downward heat flow. Upward heat flow prevailed on rainy days in the bare and irrigatedbare plots but was effectively slowed under surface residues. Overall, heat gains during the rainy season were greater than heat losses. Predicted soil temperatures, using a model from the temperate zone, were consistently lower than measured temperatures. The differences between measured and predicted temperatures decreased when the soil was either irrigated or mulched. The differences, however, were within ranges reported for soil temperature predictions in temperate regions.