Tensiometers for Precision Irrigation

Choose the model by the soil or growing medium, then the length by the depth. The SR (Standard Range) has a 0-100 cb gauge for medium to heavy soils. The LT (Low Tension) has a 0-40 cb gauge for coarse, sandy and potting soils where tensions above 30 cb are not expected. The MLT (Miniature Low Tension) is a compact 0-40 cb instrument for small containers and pots. Agrinovo supplies the SR and LT in every length (15, 30, 45, 60, 90 and 120 cm), chosen per order to match the measuring depth. Many operations place more than one depth per station to see the full moisture profile.

A tensiometer measures soil water tension directly with a water-filled tube and reads accurately in the wet range, but the tube needs periodic refilling. A granular matrix sensor like the Watermark 200SS is maintenance-free, covers a wider 0-200 cb range, and lasts multiple seasons, at a coarser accuracy. Tensiometers are the choice for precise wet-range irrigation; the Watermark is the choice when low maintenance and a wide range matter more.

Install the sensing tip at the depth where the crop draws most of its water, and choose the instrument length that puts it there: the SR and LT are supplied in 15, 30, 45, 60, 90 and 120 cm lengths. A second, deeper instrument is useful to confirm that water is reaching, and not passing below, the root zone.

Yes. A tensiometer holds water in its tube and needs periodic refilling and servicing, especially after the soil dries past the point where the tube can hold vacuum. If maintenance-free operation is the priority, the Watermark 200SS granular matrix sensor provides soil tension data without the refilling routine.

Yes, when the tensiometer has an electronic output. The standard SR, LT and MLT are read on a mechanical gauge. For the SR and LT, Irrometer offers transducers that replace the gauge (RSU-V, 0.5 V to 4.5 V, and RSU-C, 4-20 mA) and an automatic switch (AVS); ask us about availability. With a transducer wired to an Agrinovo Genesis controller, the reading drives closed-loop irrigation: when tension rises past your dry threshold the controller opens the valve, and when it falls past the wet threshold it closes. Readings, alerts, and automation run through the IoT soil monitoring platform.

The price depends on the model (SR, LT, or MLT) and its length, whether you read it manually from the gauge or connect it to a controller for continuous logging, and how many stations your plot needs. Our pricing is by tailored quotation, so you pay for the configuration that fits your field rather than a generic bundle. Request a quote with your crop and plot details and we will come back with a concrete recommendation.

The practical rule: one measurement station per homogeneous irrigation zone (same crop, same soil type, same drip line), usually with two depths per station: one in the heart of the root zone and one below it to check for deep percolation. Start with one or two stations in the most representative zones and expand after a season, once you see where the real variability is.

Tensiometers work in most agricultural soils. In fast-draining sandy soil tension changes quickly, so frequent reading matters (an advantage for controller-connected units); in heavy soil the changes are slower. The SR reads 0-100 cb for medium to heavy soils, and the LT and MLT read 0-40 cb for coarse soils and growing media; for soils managed unusually dry, consider a granular matrix sensor with a wider range.

Many years, given simple seasonal maintenance: refilling the fluid at the start of the season, checking vacuum, and keeping the ceramic tip wet. At the end of the season, remove, rinse, and store with the ceramic tip protected. The tube and gauge are simple mechanical components with no field-degrading electronics.