The study of the temperature and moisture regimes of the cultural podzolic sand soil had been taken in 1982-1985 years in the region of the north-taiga subzone of the Komi Republik of Russia. The crop was the potatoes. The year sum precipitation fluctuated from 159 mm to 270 mm during the period of the planting and havesting. The average daily sums temperature flactuated from 1235 degrees C to 1285 degrees C during these same periods. The absolute minimum temprature at the soil surface was - 3,5 degrees of C. During the planting and growth period the average daily temperature shortage varied from 2 degrees of C to 4 degrees of C.

The polyethylene film mulch on soil, watering as well as both methods together were the most effective among the other 19 methods of improving the thermal regime. The average exceeding of temperature in the 20 cm layer of the soil reached 2,9 degrees of C with the help of the colourless polyethylene film mulch and this exceeding reached 3,7 degrees of C with the help of watering together. The black film mulch, watering reduced the gradient of temperature of the soil, decreased the amplitude of the average daily temperatures, the ground frosts probability came down.

There isn't the excess moisture of the ploughing layer of the soil if the even fall of the precipitation is at the average many years level or more but still some periods of nearly 50 days long have been watched when the moisture hasn't been sufficient. The improvement of the water regime with the help of irrigation taking the normal field moisture capacity into account went nearly 10 days. The black film mulch, bringing the organic fertilizes into the soil, cultivation with latex gave the fine effect to the soil moisture.

As the result of investigation the equation of relation between the average ten days precipitation and the soil moisture, the equation of the determine the soil temperature upon the average day temperature of the air and soil moisture due to the film mulch and without it have been derived.

Dr. Vasily V. Mokiev
Departament of Soil Science
Institute of  Biology
Komi Scientific Center
Ural Division of Russian Academy of  Sciences
Komunistcheskaya st., 28.
Syktyvkar 167610, Russia
Phone: 42-51-15. 42-52-40.
Fax: (8212) 42-01-63
E-mail: biol@omkomi.intec.ru