土壤水分及土壤-大气界面对麦田水热传输的作用

文章根据1996年在中国栾城农业生态试验站观测的田间试验资料,分析了土壤水分和土壤-大气界面对麦田水热传输的抑制和加速作用。对于显热和潜热输送,土壤水分起决定作用,土壤水分越小,显热通量越大,潜热通量越小,反之亦然。只在土壤水分较小时界面厚度对显热和潜热输送作用较大。对于土壤热输送,界面厚度起决定作用,界面厚度越大土壤热通量越小。分析还发现60cm深处土壤水势与叶水势和大气水势的相关系数较其它深度处的土壤水势大。0～60cm土层是确定土壤水分运动对界面水热传输影响的一个良好的指示层。

The effects of soil moisture and soil atmosphere interface on water heat transfer in winter wheat field

Soil wheat atmosphere continuum is conceptualized as the interface between soil and atmosphere in winter wheat field, with canopy and soil surface being top and bottom boundary respectively. The depth of the interface is defined as the function proportional to (green) leaf area index. Based on the experiments conducting at Luancheng Agro ecologic Experimental Station, Chinese Academy of Sciences, from April to June, 1996, the effects of soil moisture and soil atmosphere interface on water heat transfer in winter wheat field are analyzed. Soil moisture plays an important role in latent and sensible heat transfer. The drier the soil, the higher the sensible heat flux and the smaller the latent heat flux, and vice versa. This feature is especially remarkable when soil is wet. When soil is very dry, the depth of the interface dominates the two ransfers. For soil heat transfer at land surface, the depth of the interface is a more prominent influential factor than soil moisture. The analysis shows that the relationship between leaf water potential and atmosphere potential with the soil moisture matric potential at 60 cm depth is closer than the relationship between the two potentials with the soil moisture matric potentials at the other depths of soil. The soil layer of top 60 cm is a good index to study the effects of soil moisture and soil atmosphere interface on water heat transfer. It is also shown that the change of soil moisture potential acts as a macroscope of the variation of the water movement within the interface and above the interface.