Week 22: 3 October – 9 October

Our final set of experiments for the plants is finished!

Here are our key findings:

1. The set-up is able to replicate results for microgreens under several different substrates
2. There is limited growing on microgreens with large seeds (snow peas)

Week 21: 26 September – 2 October

10 days later, the experiment is complete.

Here are our key findings:

1. Mung beans grow better in the presence of the soil substrate
2. The mung beans were able to grow up to 120mm, which is considerable but still less than that in the previous experiment. We postulate it is due to the difference in environments (outdoors vs indoors) they were placed in.

After finding out that the set-up is effective in growing mung beans, we wanted to extend the experiment to other types of plants. Thus, we set out with our final set of experiment. The aim of this experiment is to determine if the results from our 2nd experiment can be replicated using microgreens instead of mungbeans.

Independent variable

• Type of soil substrate (no soil substrate, zeolite, vermiculite)
• Type of microgreens (radish, pea)

Dependent variable:

• Number of surviving microgreen seeds

Control variables: 

• Volume of water used for irrigation (30ml)
• Concentration of NPK solution (150ppm)
• Frequency of irrigation (Every 24 hours)
• Thickness of soil substrate (2cm)
• Location (Indoors, outside MnT lab)

 

Week 20: 19 September – 25 September

After much trials and errors, our set-up is finally complete!

With the completed set-up, we proceeded to the next set of experiment for the plants. In this experiment, our objective was to test if the results from the previous experiment with manual irrigation could be replicated using the automated set-up.

Independent variable

• Presence of soil substrate (vermiculite)

Dependent variable:

• Average plant length from the roots to the top

Control variables: 

• Type of plant (mung beans)
• Number of seeds (30 each)
• Volume of water used for irrigation (30ml)
• Concentration of NPK solution (1000ppm)
• Frequency of irrigation (Every 24 hours)
• Location (Indoors, outside MnT lab)

Here is a video of the sprinklers watering the plants after setting the time of irrigation on our IoT interface.

Week 19: 12 September – 18 September

When testing out our water sprinklers, we realised that our electronics were getting rained on too much. After considering the safety of our team members, we decided to use corrugated boards as a cover for our DC motor, bread board and wires to waterproof it.

We also tried to add an aluminium profile at the base of the set-up so that the water tank could be moved alongside the PVC structure as 1 whole unit.

Unfortunately, the wheels and aluminium profile could not support the weight of the water tank, and the structure came apart.

We hence decided to scrap our idea.

 

Week 18: 4 September – 11 September

The structure was getting bulky and hard to transport so we decided to add wheels to it. Wheee!

Week 17: 28 August – 3 September

After 13 days of running the experiment, we obtained our results!

Here are our key findings:

1. The changes in ratio of hydrorock:soil substrate height used was negligible to the experimental results.
2. Our hypothesis was proven when zeolite is used as a substrate as maximum average plant height was greater by ~11% for the set-up with zeolite and hydrorock (180mm) compared to the set-up with only zeolite (160mm). Additionally, the set-up with zeolite and hydrorock showed a faster growth rate compared to when hydrorock was absent.
3. For the set-up with vermiculite as a soil substrate, our hypothesis was not proven as hydrorock had no effect on average plant height.
4. Hydrorock is only suitable for select soil substrates.

Week 16: 21 August – 27 August

We started a new set of experiment to grow the mung beans while the set-up is still being built and assembled. The main purpose of this experiment was to determine the effect of hydrorock on plant growth.

We hypothesized that hydrorock would promote plant growth of mung beans due to its excellent water retention properties that would allow the mung beans to absorb water continuously when required through capillary action. We also varied the height of the hydrorock and soil substrate used to determine the best ratio for plant growth. Vermiculite and zeolite were chosen as the soil substrate due to results from the literature review and previous experiment showing they were the best growing medium for mung beans.

Independent variable

• Height of hydrorock (0cm, 1cm, 2cm)
• Soil substrate (vermiculite, zeolite)
• Height of soil substrate (6cm, 5cm, 4cm)

In this experiment, we also established strict parameters to quantify plant growth. To measure plant growth, we decided to take measurements of the overall plant length from the roots to the top of the mung bean every 2 days.

Dependent variable:

• Average plant length from the roots to the top

Additionally, we established some control variables to minimise the effects of external factors on our experimental results.

Control variables: 

• Type of plant (mung bean)
• Number of seeds (30 each)
• Depth at which seeds planted into soil substrate (1cm)
• Total height of growing medium
• Volume of water used for irrigation (30ml)
• Concentration of NPK solution (1000ppm)
• Frequency of irrigation (Every 24 hours)
• Location (Outdoor terrace)
• Temperature/Rainfall/Wind*

* The experiment is conducted outdoors so we are unable to control the exact conditions. However, they are all placed at the same location so they are subject to the same outdoor conditions.

Control set-up:

• Mung beans planted on cotton as a growing medium
• Mung beans with no growing medium

 

Week 15: 14 August – 20th August

We completed the code for the water level sensor which monitors the water level in the water tank and alerts the user on the IoT mobile app when the water level reaches below a certain level so that the water can be refilled. When water level is sufficiently high, real time data would be displayed and no alerts would be sent out to the user.

 

Additionally, the code for the water pump and water flow sensor is completed.

Week 13: 31st July – 6th August

We modified the top layer of the PVC pipe structure slightly to accomodate the sprinklers. 2 additional PVC pipes were fitted onto the top layer and the sprinklers would be attached to the bottom of the pipes for irrigation of the plants.

Week 12: 24th July – 30th July

On 27th July, we held a meeting with 2 representatives from Hydrorock to find out more about their product and determine if it will serve our project’s needs and act as a suitable substrate to enhance plant growth.

We found that hydrorock has many excellent properties and could be a better replacement for hydrogel in our initial set-up. Hence, we decided to tweak our current experiment and replace hydrogel with hydrorock to determine which is a better substrate that can be paired with our soil-less medium, zeolite.

 

Week 10: 10th July – 16 July

We completed the code for the water flow sensor, and are now able to receive the data collected from the water flow sensor. This allows us to track whether or not the sprinklers and water pump are working well, and whether the plants are being irrigated.

 

The nutrient dispenser has also been 3D printed and it will be able to dispense the NPK pallets into the water tank with a push of a button on the IoT interface after the code has been integrated into the IoT cloud.

Week 9: 3rd July – 9th July

We decided to implement an IoT cloud to streamline communication between the various electrical components as well as provide a centralised interface for the user to control plant growth.

 

For the irrigation IoT interface, the idea is to have an automated irrigation system whereby the user can set the irrigation frequency themselves and control the volume of water each time. Users can also toggle on irrigation manually when required.

For the nutrient IoT interface, the concentration of nutrients necessary for plant growth (Nitrogen, Phosphorus & Potassium) would be displayed and when the concentration falls below a certain threshold, the nutrient dispenser and stirrer will be activated to increase nutrient concentration level. Similar to the irrigation system, the nutrients may also be manually dispensed by the user.

Week 8: 26th June – 2nd July

On June 27th, our focus was on planting mungbeans on different growing mediums to see which growing medium was most suitable to use with hydrogel. These growing mediums are rockwool, sand, zeolite, perlite, vermiculite, and clay pellets. We also had a hydrogel-only growing medium and a control medium, where mungbeans were planted directly without a growing medium.

In total, we had fourteen unique growing mediums, and each growing medium had a hydrogel and non-hydrogel variant. This was to confirm whether any enhanced plant growth was owed to the hydrogel. We obtained our hydrogel by  extracting it from baby diapers, like the previous time.

To ensure proper water drainage and prevent waterlogging, we implemented a porous woven fabric on top of a tray. This setup allowed excess water to drip down while keeping the growing medium in place. The tray, together with the woven fabric, was attached to a PVC pipe structure that was constructed with two layers. This design facilitated the flow of excess water from the first layer to the second, effectively watering both layers.

With our setup in place, we planted 80 mungbean seeds in each growing medium. Though our self-watering system is not yet complete, requiring manual watering for now, we watered the plants with 100ml of a nutrient solution, consisting of 10g/dm3, every 36 hours. Once our self-watering system is fully operational, it will provide a completely self-sufficient watering solution for the plants.

Throughout the week, we observed the growth and development of the mungbeans. We found that most of the growing mediums were not suitable for plant growth due to various reasons. For example, growing mediums with high porosity and low retention rates such as perlite and clay pellets resulted in poor growth as the mungbeans did not have sufficient water to germinate. Conversely, the water retention capabilities of rockwool were too high, resulting in the mungbeans to rot shortly after germinating due to waterlogging. Nonetheless, we found that hydrogel positively enhanced plant growth for most of the growing medium such as zermiculite and sand, where only the hydrogel variants showed plant growth. We found that zeolite was the best growing medium for the plants, and was the most compatible with hydrogel, as the mungbeans showed the most growth in that growing medium.

Week 6: 12 June – 18 June

We wanted to test out and see whether the mungbeans were able to grow on hydrogel so we conducted a simple experiment to track the growth of the mungbeans.

We first extracted the hydrogel from baby diapers by peeling open the diapers and brushing the small hydrogel beads into a container. Then, we lay a porous woven fabric on top of a tray to prevent waterlogging, and added the hydrogel onto it. We added different volumes of hydrogel to see which was the most suitable for plant growth.

After observing the mungbean growth over a week, we found that they did not germinate. We postulated that hydrogel alone was insufficient as a growing medium, and decided to test out different growing mediums to pair with the hydrogel instead.