杨凌区浅层土壤水分与深层土壤水分的关系研究

通过测定陕西杨凌区不同灌水条件下冬小麦的土壤水分变化,研究了浅层土壤水分与深层土壤水分的关系。结果表明:土壤含水量随土层深度的加深,呈先上升,后下降,又上升的变化趋势。在自然降水或灌溉条件下,土壤水分的变化程度随土层深度的增加,呈剧烈—缓和—剧烈—缓和的趋势。表层20、30、40、50 cm各土层含水量分别与0~150 cm各土层含水量的相关性较好,并且土层相邻越近,其相关性越好,说明由表层土壤含水量来推算深层土壤含水量是可行的。基于Biswas土壤水分估算模式,由表层30~40 cm的含水量来推算0~100 cm各土层含水量的精度较高,由表层20 cm的含水量来推算100~150 cm各土层含水量的精度较高。总灌水量及灌水次数对含水量的影响,直接影响到估算模式参数的取值及估算精度。

Relationship between soil moisture in surface layer and in deeper depth in Yangling

According to the measurement of soil moisture variation of winter wheat under different irrigation condi-tions in Yangling, the relations between soil moisture in surface layer and that in deeper depth is analyzed. The results indicate: with the soil layer deepening, the changing trend of soil moisture presents a high-low-high fluctuation. The variation degree of soil moisture, as the soil layer depth increasing, shows a tendency of violent-gentle-violent-gentle under natural precipitation or irrigation conditions. The soil moisture of various layers of 20 cm, 30 cm, 40 cm and 50 cm below the surface layer is well related with each layer of 20 ~ 50 cm, and the closer the two soil layers, the better relativ- ity between them. It proves good results to estimate the soil moisture of deeper depth by suface layers. Based on Biswas soil water estimation model, to estimate soil moisture of 0 ~ 100 cm by the experimental data of 30~ 40 cm and to esti-mate that of 100 ~ 150 cm by the experimental data of 20 cm both have good relativity. The influence of total volume and times of irnigation directly affects the value and accuracy of model parameters.