Soil moisture sensor, ion meter, and lysimeter

The soil moisture sensor indicates when and how much to irrigate; the ion meter shows the status of available nutrients; and the lysimeter allows for monitoring the amount of water and nitrate leaching below the root zone. This combination closes the loop: irrigation → soil → plant → drainage → decision-making.

Soil moisture sensor

The soil moisture sensor reveals the actual water content in the soil and determines when a field requires irrigation. Managed via the Plantae smart irrigation platform, these sensors help reduce water consumption, prevent crop water stress, and facilitate data-driven—rather than intuition-based—decision-making.

They can be installed with probes of various lengths to suit the crop’s root system or positioned to align with the irrigation wetting pattern, particularly in drip irrigation setups. Depending on the crop type—or in applications such as landscaping or sports fields—they can also be buried underground.

Plantae technical guidelines:

• Follow our technicians’ recommendations regarding the number of moisture sensors and their installation depths.
• Assess soil composition.
• Supplement with a soil temperature sensor.
• Install a weather station based on the plantation’s specific needs.
• Ion meter

An ion meter measures the concentration of specific ions within a solution.

For fertigation (nutrient application via irrigation), monitoring the following is particularly important:

• NO₃⁻ (nitrate ion).
• NH₄⁺ (ammonium ion).
• K⁺ (potassium ion).
• Ca²⁺ (calcium ion).
• Na⁺ (sodium ion).
• Cl⁻ (chloride ion).
• …and, depending on the system, other ions.

The Plantae electrical conductivity (EC) sensor is a crucial tool for monitoring soil salinity, especially in fertigation and precision agriculture systems.

Electrical conductivity (EC) measures a solution’s ability to conduct electric current. This capacity increases as the concentration of dissolved ions rises. When irrigation water and fertilizers are applied continuously, salts can accumulate in the root zone. If the salt concentration becomes too high, the plant struggles to absorb water, even if there appears to be sufficient moisture in the soil.

Lysimeters

A lysimeter answers a key question for farmers: How much water is actually leaving the root zone, and how much nitrate is it carrying?

They are essential instruments for studying soil-plant-atmosphere exchange and drainage.

Objectives to be achieved with the soil moisture sensor, conductivity sensor, and lysimeter:

• Sufficient moisture in the root zone environment; maintaining an optimal moisture range.
• Absence of water stress throughout the crop’s phenological stages.
• Avoidance of prolonged saturation and consequent water loss.
• Minimal unnecessary percolation (filtration and leaching), preventing the loss of water and nutrients.
• Maximum root absorption, ensuring the plant has what it needs at all times.
• High performance, improving both yield and quality.
• Minimal water and energy consumption.

Technical oversight: At the forefront of research, Plantae collaborated with the Region of Murcia’s Training and Technology Transfer Service to organize a specialized seminar on “soil moisture sensors + ion probes + lysimeters.” The project was carried out in the context of the Campo de Cartagena and Mar Menor area.

Spanish Regulations

Royal Decree 1051/2022, on sustainable nutrition of agricultural soils, establishes regulations for fertilization and aims to prevent water pollution by nitrates. (+INFO)

• Adjust irrigation doses and frequency to the crop’s needs.
• Consider the soil’s moisture retention capacity.
• Prevent nutrient losses through leaching.
• Use a soil moisture sensor as a support tool.
• Promote localized irrigation whenever technically feasible.
• Spread fertilization applications.
• Adapt nutrients to water requirements.
• Avoid excessive salt accumulation.

Sources of the article: Plantae agro