Freddie’s Agritech Project

Introduction:

My agritect project is a hydroponic plant growing system that utilized both aeroponics and vertical farming method for the basic planting mechanism, here I list some benefits of the aeroponic system:

• The plant roots have constant access to oxygen and nutrients, they tend to grow faster and produce higher yields compared to soil-based cultivation. This can lead to quicker harvests and increased productivity.
• The absence of soil reduces the risk of soil-borne diseases and pests, common in traditional agriculture. This can result in healthier and more robust plants.
• Aeroponics systems are often designed vertically, allowing for high-density cultivation in limited space. This is particularly valuable in urban agriculture or areas with limited land available for farming.

My project contains a self-circulated water and nutrient system, and a wooden frame that provides lights on a vertical direction for the plants, I also build a water-level monitor that inspect the abundance of water in my planting system.

For plants, I choose bok-choy, one of my favorite local vegetables in China. I’ve started consuming them since shortly after I was born and throughout my childhood I constantly consume and compare all kinds of bok choys, forming a relatively deep understanding of its growing conditions.

Aim

I consider this project an experiment and also a prototype for a hands-on device that largely promote the adaption of urban farming in people’s daily life. So I aims at not only to grow a small tower of plants that can be easily accessed in an indoor environment but also to explore the accessibility of implementing intelligence farming as an urban lifestyle.

Initial concept drawing

My initial concept sketch was a lot more complicated than the current one. I simply want a piece of light under every single basket of my plants. After communicating with my professor, Andy suggested that this way was too complex for an individual project, so instead of adding separated lights, he suggested that I build a bigger frame and put the lights vertically around the main body so that every direction reaches more equal amounts of light. It turns out that this method is so successful that it boosts the healthier color growth among those bok-choys. The rest parts are almost the same aligned with my current project.

Development process

Structure Design

The structure of the main body consists of several parts:

• bucket
• water pump
• a plastic hose for the water pump
• planting module adaptor
• five layers of tri-baskets planting module
• water pump filter layer
• top lid

The water-circulation is well-performed with the help of these components and the structure it formed, here are a few steps explaining how the circulation works:

1. the water pump will pump water through the plastic hose all the way up to the top
2. each layer of the module has a structure of two circles, each independent of each other, the inner circle is for the plastic hose to go throw, the outer circle with small holes around is for the water that pumps to the top to flow down and irrigate the roots of the plants that are positioned within the range of the holes
3. the water will go throw each layer from the small holes, after watering thoroughly through all five layers, the water will go throw the adaptor and returns back to the bucket

The module I use actually comes from an open-source platform called thingiverse, my professor showed me the design of the module and suggest that I directly use this module to 3d-print. I shall express my large appreciation to this design: https://www.thingiverse.com/thing:5712775/files

The seedlings of the bok-choy will be supported by a type of rockwool, a material that allows water retention and drainage.

Here is the photograph for the main planting tower:

Wooden frame and lights

The wooden frame is independent of the main tower, so it’s more convenient for me to make adjustments. The wooden frame is built with log strips, screws and angle irons, which allows for modifications. On each corner of the vertical strips, I use a special drill to make small new platforms for the lights to secure.

Sensors and Actuators

For sensors I use ultrasonic distance sensor to inspect the water level inside the bucket. Basically I let the Arduino conduct a simple calculation which is the total height minus the distance of the sensor value:

water_level = 37.00 – distance

Since the aeroponic is a high water-efficient system, I set the time of sending a new value for every one hour, 3600000 seconds in millis() so that I can check the water level on a proper pace.

For actuators I have a 39w water pump that has a maximum pump height of 2m, four 6W LED lights for growing, all purchased through online vendors.

Electronics:

I use a breadboard and ESP-32 to connect all my wires, here is how it looks like in general:

For my water pump and lights, I utilized the method shown in class that connects to the relay, I bought a 6 routes 5V relay that supports more actuators, I use soldering to extend all the wires and cover the connections with 3M tapes. Same thing I also modify with the connection of the ultrasonic.

Automation / Coding / Node-Red / Dashboard

The two dominating functions are realized through the automation with the association of ESP-32 board and Node-Red. The automation for water irrigation is of a high frequency which I allow it to turn on for 20 seconds in every minute.

By imitating what I did for the water pump, I add similar codes for LED lights when I try to use the MQTT server. I add subscribe() for waterpump and lights , publish() for waterlevel

For the lights, since I need the lights to be turned on/off according to real-time clock. So I decided to use Node-Red to realize this automation:

In Node-Red, I can use a node called switch simply for turning on/off my actuators:

The on/off payload for the switch is sending a value which I set as integer 0 and 1 to my MQTT server, the server receives the data and them send to my ESP-32 board where I insert codes for subscribing to certain topics of the MQTT server.

So here it comes to the tricky part where the automation works:

In Node-Red there is another node called insert a value and it can be activated under certain loop or during certain intervals the user sets so for both the water pump and the lights.

For the lights it is relatively easy, there is an option setting them to start at certain time in one day, so I set 6:00 AM for on and 23:00 PM for off. Payloads are accordingly 1 and 0.

For the water level I used the email-sending function introduced in class, I change some values in the nodes and sets the condition for sending emails: if the water level is below 130mm, it will set a reminder that sends a water level warning email to my email account at a frequency of a day.

Results and reflection

The automation works well after several adjustments, except for water splitting in the ultrasonic that sometimes makes it disabled. The frequent of irrigation and nutrients boost the size of the bok-choy, while the lights boost the color and appearance of the plants.

However, sometimes things go wrong:

Someday during my modification, I accidentally turned off the water pump for one night, the next morning when I came by and check the plants, they seemed to die quickly, then I checked the roots, the color turns black and it becomes smaller, I was astonished that aeroponic system rely highly on the water circulation. Then I learned the lesson that always make sure the water circulation functions well before leaving my plants alone.

Another significant problem is the bugs, I find tiny green bugs gathering around the back side of my bok-choy and the amount is significantly high, and I can find small holes bitten by them on the leaves. I’ve tried different methods: Spraying soap water, getting rid of the bugs, but after one or two days they multiply again. So I decide to clean the entire plants, several days before the presentation, I started to take the support rock out and clean every single one of my bok-choy, I find those small bugs not only lie behind the leaves, but also on the stem and even the upper part of the root, then I gave all my plants a thorough shower. Also, since they’ve grown bigger, I removed all the support rocks then.

Growing plants is much more complicated and difficult that merely producing a project. One has to take care of those plants on a daily basis, but I think that’s the fun of the whole project: watching the plants to grow from seedlings to beautiful plants is a process of curative happiness. I think this project is not only for me to learn more skills in electronics and coding, but also an awareness of understanding the difficulty and value of our everyday foods for consumption.

Things for improvement may be adding the weather or sunlight monitor to give my plants more precise amount of adequate lights. Also think of ways to solve the water splitting on the ultrasonic to prevent the error emails. If I had more time, I will also consider adding black acrylic boards to seal the frame and add a door that could open and for better operation on the system because the vertical lights may be a little uncomfortable to directly look at.

Final pictures

By Freddie Yang