FEATURES OF TEMPERATURE REGIME OF PEAT SOILS OF NORTHERN TRANS-URAL REGION

Abstract

Results are given from long-term field studies of temperature regime of drained peat soils of Northern Trans-Ural region. It is shown that the maximum temperature of the peat soil’s arable layer is observed in July, and reaches 18.2-19.7°C. The strong relationship between air and soil temperatures during the growing season was found in the 0.2 m layer (r = 0.49-0.67). The temperature regime of subsurface is increasingly dependent on winter cold reserves. The transition of peat soil temperature in the arable layer across 5°C takes place in the first ten-day period, and across 10°C in the third ten-day period of May. The length of 5°C temperature period in the 0.2 m layer of peat soil is 10-12 days shorter than that of gray forest soil, and 13-15 days shorter than that in the 0.4 m layer. The active temperatures period in the arable layer makes up 120-135 days, and 96-127 days at the depth of 0.4 m. At the depth of 1 m, the transition of temperature across 10°C does not occur. The average annual sum of effective temperatures in the arable layer is 2187.4. The transition of peat soil temperature in the arable layer across 0°C was observed in the first and second ten-day periods of December that is 10-20 days later than in the zone of gray forest soil. The lowest temperature in the peat soil’s arable layer of - 9.5°C was observed in February 2012. The maximum depth of frost penetration in peat soil of 0.45-0.65 m is reached by the beginning of snow melting (late March to early April), and considerably depends on pre-winter humidity (r = 0.70-0.75), air temperature (r = 0.77-0.83), snow depth (r = 0.69-0.75), and field surface conditions.