Abstract: In this paper, dynamic variations of soil moisture for climate observation field and cropland using neutron probes were compared. The results showed that the differences of both were obvious. The regression equations of neutron probes(IAG-Ⅱ)in three climate observation fields of Shenzhou, Huanghua and Bazhou of Hebei province were built. By comparison with the data measured using soil drill, for the soil below 30cm, one regression equation of neutron probe was adopted in Shenzhou and two regression equations in Huanghua. The regression equation of neutron probe (503DR) in examination plots of soil moisture in Gucheng was built. By comparison with the data measured using soil drill, the regression equation could be adopted for the soil below 30cm. For the soil between 0-30cm, measuring soil moisture using soil drill was proposed.

Key words: Neutron probe, Neutron probe, Climate observation field, Cropland, Soil moisture