Introduction to the LI-300 and LI-350

Welcome, and thank you for your purchase of the LI-300 or LI-350 Soil Moisture Sensors. If you have just taken delivery of the product, check the packaging list to be sure you have received everything you ordered.

The LI-300 and LI-350 Soil Moisture Sensors feature stainless steel electrodes (tines) and circuitry that is enclosed in a water-tight housing and potting compound. The cable is equipped with a ferrite bead to minimize electrical interference. Cables terminate with bare leads or an M12 connector (see Table 1‑1).

Figure 1‑1. Components of the soil moisture sensor. Both the LI-300 and LI-350 have a soil temperature thermistor inside one tine. The cable includes a ferrite bead on the terminal end. The ferrite bead is required to prevent electrical interference.

The LI-300 and LI-350 measure numerous soil parameters, reporting soil volumetric water content (VWC), soil temperature, and soil electrical conductivity (LI-350 only). The LI-300 provides analog output, whereas the LI-350 is an SDI-12 device, reporting data using the SDI-12 protocol. Both sensors are available with a variety of cable lengths.

Table 1‑1. LI-300 and LI-350 cable length, termination, and output options.
Name Cable Length Custom Cable Lengths Termination Output
LI-300-BL 5 m (LI-300-BL-5) 10 m, 25 m, 40 m Bare Leads Analog
LI-350-BL 5 m (LI-350-BL-5) 10 m, 15 m, 25 m, 50 m, 75 m Bare Leads SDI-12
LI-350-M12 1 m (LI-350-M12-1)   M12 Connector SDI-12
5 m (LI-350-M12-5)  

Warning: Puncture hazard. Tips of the tines are sharp and may cause a puncture injury. Handle probes with care and keep a protective foam cover in place when the probe is not being installed or in use.

LI-300 performance characteristics

The LI-300 provides measurement data as analog signals. It requires a power supply of 3.05 to 15 VDC, with current consumption of < 10 mA for < 12 ms while active and 1.3 mA while passive. Additional performance characteristics are given in LI-300 specifications.

LI-350 performance characteristics

The LI-350 provides measurement data as a digital signal using the SDI-12 protocol. It requires a power supply of 4 to 15 VDC, with current consumption of < 10 mA for < 12 ms while active and 500 µA while passive. Additional performance characteristics are given in LI-350 specifications.