Arduino Automatic Watering System

INTRODUCTION & OBJECTIVES:

I am a basic system that utilizes Arduino for automating the watering of small potted plants or crops.

This system monitors soil moisture levels by using LEDs for indications and emitting an alarm beep if the soil is dry. If the soil is dry, the irrigation system will be triggered to pump water for watering plants.

The system utilizes an LCD screen to update on ongoing actions and a real-time clock.

The Theory (as per Wikipedia):

The amount of water within a substance, like soil, rocks, ceramics, fruit, or wood, is known as water content or moisture content. Water content is utilized across various scientific and technical fields, and is represented as a ratio that can vary from 0 (completely dry) to the porosity value of the materials when saturated. It can be provided based on volume or mass (gravimetric).

The mathematical definition of volumetric water content is given by the symbol θ.

where  is the volume of water and  is the total volume (that is soil volume + water volume + air space).
Gravimetric water content[1] is expressed by mass (weight) as follows:

where  is the mass of water and  is the bulk mass. The bulk mass is taken as the total mass, except for geotechnical and soil science applications where oven-dried soil (, see the diagram) is conventionally used as .
To convert gravimetric water content to volumetric water, multiply the gravimetric water content by the bulk specific gravity of the material.
In soil mechanics and petroleum engineering, the term water saturation or degree of saturation,  is used, defined as

where  is the porosity and  is the volume of void or pore space. Values of Sw can range from 0 (dry) to 1 (saturated). In reality, Sw never reaches 0 or 1 – these are idealizations for engineering use.
The normalized water content, , (also called effective saturation or ) is a dimensionless value defined by van Genuchten[2] as:

where  is the volumetric water content;  is the residual water content, defined as the water content for which the gradient  becomes zero; and,  is the saturated water content, which is equivalent to porosity, .

In the Pictures you have an overview of the components used.

Data from the soil moisture sensor set:
When the soil is dry, the impedance will be high and the LM-393 will show a high value on the output.
When the soil is wet, it will show a low value in the output.
The 3 LEDs range can be defined as:
– Soggy soil –  moisture between 0 and 500;
– Wet soil – moisture between 500 and 800;
– Dry soil – moisture between 800-1023;
The module has one digital output and an analog output. (in the project, should be used to analog output)

The water level sensor:
This sensor must be made (homemade) on phenolite board, with spacings of 1 mm between trails and trails with 1 mm of thickness.