Discuss the working principle behind your project.

 

Overview

Our project focuses on 2 key components — automation and plant growth. In the subsequent paragraphs, we will discuss how we have optimised each of the components in our system to ensure optimal plant growth.

 

Plant Growth

Hydrorock

Hydrorock is a fibrous, lightweight, and porous stone wool material that has gained popularity in recent years for its remarkable benefits in promoting plant growth by offering a controlled and highly efficient environment for plants. It has also been used in irrigation systems around the world as a way to reduce labour and watering frequency.

 

Hydrorock absorbs 94-95% of water as compared to its volume, and through the capillary effect, ensures the plants has consistent access to water and nutrients. This consistency allows for precise management of growth conditions, resulting in uniform plant development and higher plant quality. Furthermore, in a hydroponic system using hydrorock, nutrients are delivered directly to the plant roots in a dissolved form. This allows for precise control of nutrient concentrations, which results in faster growth rates and higher yields.

 

Additionally, hydrorock provides excellent aeration to plant roots. The porous structure of the rocks allows for increased oxygen diffusion to the root zone. This ensures that the plants receive an optimal amount of oxygen, which is crucial for root respiration and overall growth. Adequate oxygen supply also reduces the risk of root diseases caused by anaerobic conditions, so the plants have a higher survival rate.

 

Growing Medium

For our growing medium, we chose a soil-less substrate as we wanted to eliminate the risk of soil-borne diseases and pests, especially since we were growing mung beans whose growing environment of being nutrient-rich and moist is particularly favourable for pathogens like Salmonella and Escherichia coli to grow.

 

From our initial testings and experiments, we found that the beansprouts showed the most growth in zeolite as compared to other growing mediums. This corroborated our research and hypothesis as zeolite has a high water retention, porosity, and cation exchange capacity with a low decomposition rate that ensures optimal plant growth.

Plants

We chose mung beans as the plants we were going to experiment on due to their short germination and growing period. They typically germinate and reach maturity within 14 to 25 days, which is ideal for our project that requires numerous testing and trials in a short timeframe.

 

Subsequently, we grew microgreens to test out whether the results from previous experiments using mung beans could be replicated across different plant types.

Automation

Here is a block diagram to explain how each component is linked.

IoT interface

Through Arduino IoT, our set-up provides the user an easy-to-use interface for them to make adjustments to the irrigation frequency, irrigation volume, nutrient concentration, and timing of the UV lights based on the requirements of their plants.

 

Additionally, through the water level sensor and TDS sensor, the user is able to monitor the water level and nutrient concentration in the set-up to ensure there are no anomalies.

 

IoT interface for UV lights

Nutrient Dispenser

The nutrient dispenser consists of a V-shaped structure to allow the pellets to fall naturally, as well as a fitting for the screw and stepper motor. The screw pushes out the nutrients pellets for every rotation so the nutrients can be dispensed.

In the water tank, there is a TDS sensor that will read the PPM (parts per million) of the water, which is sent to the IoT cloud so the real time nutrient concentration is displayed to the user.

 

Irrigation system

The irrigation system consists of a pump that draws water from the base container to irrigate the plants, and a set of sprinklers that ensure the relatively even spread of water in the plants.

Part of the irrigation system also includes the water flow sensor and the water level sensor. These provides real time feedback and allows for offline synchronisation.

 

UV LED Lights

The UV light has a 700nm wavelength which is optimal for plant growth. Like the irrigation system, the user can schedule the timing at which the UV lights are turned on. It is recommended for the lights to be turned on for a maximum of 12 hours each day to optimise plant growth as the plants require time to rest and stop photosynthesis.

The UV lights have been soldered to ensure a stable connection.