*1.1.6 Dielectric sensors*

Dielectric sensors are used for measuring the soil moisture levels by the utilisation of the dielectric constant of the material. It defined as the electrical property, which is getting changed according to the content of soil moisture (**Figure 7**).

*Internet of Things and Machine Learning Applications for Smart Precision Agriculture DOI: http://dx.doi.org/10.5772/intechopen.97679*

**Figure 6.** *Mechanical sensor.*

**Figure 7.** *Dielectric sensor.*

These sensors embedded with rain gauge stations and arranged around the farm. While the vegetation level goes down, the observation on soil moisture conditions can be performed by them. Also, the soil moisture sensors used the soil's dielectric constant to justify the content of the volume of water and the transmission of electricity based on the soil's capability depending on its dielectric constant. The dielectric constant land's water is larger compare with air, so that, if the water content of the soil increases, the increment of the dielectric constant of the soil will also be recorded. So, the constant dielectric measurement provides a fair observation of water content.

### *1.1.7 Airflow sensors*

Airflow sensors used to measure the permeability of air of the soil. The amount of pressure needed to pressurise a certain volume of air to some depth on the land, which is used to compare the multiple properties of soil (**Figure 8**).

From multiple experiments, it is possible to distinguish between various soil types and soil structure, moisture levels and compaction. These measurements can be made not only at a single location, while in motion too dynamically. The expected outcome is the need for pressure to allow a particular amount of air to the

**Figure 8.** *Airflow sensor.*

ground in the wanted level of depth. By using such unique sensors, we can study various types of soil properties, including soil type, compaction, moisture level and structure, which produces unique identified signatures.
