Temperature Variation, Heat Storage and Heat Release of Soil in the Solar Greenhouse

The temperature has an important effect on plant growth in the greenhouse. Soil is the basis of plant growth and it is also the heat storage & heat release, it is an important part of the solar greenhouse. In the paper, the experimental solar greenhouse lies in Shenyang, Liaoning Province, China. The length is 60m and the width is 10m. The soil is black earth. The aim of the experiment is to study the regulation of heat storage and heat release and temperature variation of the soil in the solar greenhouse. The heat flow of the soil surface was recorded by the Type HFP01 heat flow sensors made by Huskeflux, the data collector is CR3000 made by Campbell, the interval time is 15 minutes. Through above, we calculate and analyze the data and get the regulation of heat storage and heat release and temperature variation of soil in the solar greenhouse. The results showed that the temperature of soil is decreased with the increased of the depth of soil, and the scope of temperature variation became small. The daily variation is obvious in the depth of 10cm and 30cm, the maximum is 9 degrees C, it became small in the depth of 50cm, till 80cm, the variation is +/- 1 degrees C, so the depth was considered steady layer. The temperature of the center is higher than the two sides, and its variation is larger than two sides. The heat transfer occurred between the south side of the greenhouse and the outdoor, the temperature of the test point of the outdoor is higher than the temperature of the ordinary soil, the average is 2 degrees C, the maximum is 4 degrees C, so the average temperature of the south side is lower 2 degrees C than the north side and the center. In the fine day, 15%similar to 18% of solar radiation is absorbed by the soil, the average thermal efficiency storage is 16.34%, more than 50% of the heat storage in the day is released in the night, the maximum is above of 100%. In the cloudy day and snowy day, there are no almost heat storage in the soil, the soil is in a state of heat release, the heat release is large in the night, even more than the fine day, the heat efficiency is much higher than the fine day.