Temperature and moisture regimes in chernozem profile under Meyer lilac plantations

Abstract

Soil temperature regime is determined, first of all, by solar radiation and heat exchange in the “soil-atmosphere” system following the temperature state of the surface air layer. In order to study the hydrothermal regime of leached chernozem under Meyer lilac, field observations of soil temperature on the warm seasons of 2018 and 2019 to one meter depth every 10 cm were carried out in the arboretum of the Research Institute of Gardening in Siberia. Warming up of the soil profile in 2019 under ornamental lilac plantations began during the second ten-days of May. However, already at a depth of 20 cm, zero temperature was observed, and below it remained negative. Winter cooling of the chernozem profile persisted until the third ten-days of June. The soil finally warmed up only in early July. Due to small amount of snow accumulated in winter, soil moisture after melting was satisfactory only in the humus horizon. The situation changed in mid-June, when the available moisture storage under the influence of precipitation reached 263 mm. By mid-August, drying of the soil profile was observed, and the available moisture storage became “unsatisfactory”. Subsequently, the rains led to increase of soil moisture. In 2018, the air temperature was much higher than in 2019. During July and August, the accumulated temperature of soil profile fluctuated within 200°C. The available moisture storage was lower than in 2019. At the beginning of June 2019, daily temperature fluctuations were observed down to a depth of 20 cm, and the accumulated temperature in the humus horizon was maximum at 7 p.m. and minimum in the morning. In August, fluctuations in daily temperature in the chernozem disappeared at a depth of 40 cm, so in the underlying horizons the temperature field acquired a stationary state.