Simulation and experimental study on the strategy of soil auxiliary heating in a solar greenhouse in northeast China

When solar greenhouses in north eastern China experience extreme weather, the internal soil requires varying auxiliary heating to ensure the normal growth of crops. In this study, considering the effects of four kinds of extreme weather on solar greenhouses, four different types of heating requirements were obtained through experiences in a Liaoshen-type solar greenhouse. Four distinct heating strategies were simulated using a soil temperature prediction model. The initial temperatures for these strategies were 13°C, 11°C, 13°C, and 14°C, respectively, while the target temperature was uniformly set at 15°C. The heating durations for the respective strategies were 432,000 seconds, 432,000 seconds, 864,000 seconds, and 1,728,000 seconds. To ensure a minimum soil temperature of 15°C within the solar greenhouse, the temperature of the heating layer located 400 mm underground needed to be maintained at or above 20°C, 28°C, 18°C, and 19°C, respectively. The simulation results were validated through experimental verification, with maximum and minimum errors of 3.1% and 0.5%, respectively. Several targeted promotional suggestions were also proposed. The model exhibited high accuracy and is capable of developing optimal and precise soil heating strategies for various types of solar greenhouses in north eastern China.