Effects of sunken depth of energy-saving solar greenhouse on the diurnal variation and spatial distribution of environmental factors in the greenhouse

LI Qing-ming1,AI Xi-zhen1,YU Xian-chang2(1State Key Laboratory of Crop Biology,College of Horticulture Science and Engineering,Shandong Agricultural University,Tai'an 271018,Shandong,China;2Institute of Vegetable and Flower,Chinese Academy of Agricultural Sciences,Beijing 100081,China).

sunken depth;energy-saving solar greenhouse;environmental factor;spatial distribution.

Taking the energy-saving solar greenhouses with the same infrastructure but different sunken depths(0,0.5,1.0,and 1.5 m) in Tai'an of Shandong Province as test objects,this paper analyzed the intercepted amount of direct solar radiation energy,and studied the diurnal variation and spatial distribution patterns of environmental factors in the greenhouses on winter solstice(December 20-24,2009) and summer solstice(June 19-23,2010).With the increase of sunken depth,the shadow areas in the greenhouses caused by sunken profiles increased gradually,the direct solar radiation energy into the interior of the greenhouses shifted from south to north,and the ratio of ground radiation to back wall radiation decreased gradually.Within the range of 0-1.0 m sunken depth,the air temperature and soil temperature in the greenhouses increased significantly with increasing sunken depth;but when the sunken depth was 1.5 m,the warming effect declined significantly,and the deviation of the lowest soil temperature increased.The deeper the sunken depth,the lower the light intensity and the higher the relative humidity in the greenhouses were.In considering of both lighting and heat preservation,the appropriate sunken depth of energy-saving sunlight greenhouses with a span of 10 m in Tai'an region should be less than 1.0 m.