Produced by Zhongtian Instrument‘TENThe soil moisture tension meter adopts high-strength polycarbonate plastic tube as the detection tube and stainless steel pressure as the reading instrument. It has the characteristics of modular design, compact structure, simple operation, and long maintenance free period, and is an effective means of observing soil moisture status.

‘TENThe standard length of the detection tube for soil moisture tension meter is:15，30，45，60，90，120 cmIt can meet the application needs of most situations. Special lengths can be customized according to user requirements.

Regarding‘TENFor detailed operation of the soil moisture tension meter, please refer to its product manual.

Introduction to Soil Water Potential and Soil Moisture Content

Soil moisture tensiometer（Soil Tesiometer）It is a method of measuring surface soil water potential（water potential，Ψ_m）Instrument for quantitative determination of plant roots（plant’s root）From the soil stagnant layer（vadose zone）Overcoming excess potential energy is necessary for absorbing water in the middle. The soil stagnant layer exists in the surface soil, and the groundwater level line is present（water table level）Above, due to the capillary siphon effect, the soil contains a certain amount of water, commonly referred to as soil moisture（soil moisture）. The usual description of soil moisture status is: volume percentage content（volumetric water content，v/v %）Weight percentage content（gravimetric water content，w/w %）Saturation degree（water saturation or degree of saturation，%）And water potential（water potential，kPa）. The focus of scalar expressions such as volume percentage, weight percentage, and saturation is on the relative amount of soil moisture, which is widely used in daily life. However, these scalars have one thing in common, which is that they cannot intuitively reflect the difficulty of plant roots obtaining soil moisture. The introduction and measurement of the concept of water potential provide an effective means.

It should be pointed out that water potential can be expressed in terms of potential energy density（J•m⁻³）It is measured in units, but generally in units of pressurekPaThe two can be converted into each other. The tension meter can work under normal conditions until75 kPaThe physical meaning of the pressure reading of a tensiometer refers to the work that plant roots must do to obtain water from the soil medium（work）It is closely related to the properties of the soil being tested.0 kPaIt indicates that the soil moisture is completely saturated, the soil pores are completely filled with water, and the plant roots do not need to overcome any potential energy to obtain soil moisture. However, soil with completely saturated moisture lacks the oxygen necessary for crop root survival! This is also the main reason why excessively wet soil is not conducive to plant growth; In general, for a coarse component sandy soil（coarse textured（sandy） soil）The favorable water conditions for plant growth are to control the soil water potential to be slightly moist30 ～40 kPaAnd for loamy soils（medium-textured（silt）soil）Or cohesive soil（heavy-textured（clay）soils）Then it is in50 ～60 kPa.

For more detailed introduction, please read the relevant technical support documents of Zhongtian Company Expression of Soil Moisture Status — Soil moisture content（Soil Water Content）And soil water potential（Soil Water Potential）”.