Best DIY cheap soil moisture sensor
15.5 years ago cheap, electronics, moisture sensor, water
My first version of my cheap soil moisture sensor has worked great for me but it did have a couple flaws. The first issue was construction, though I had great luck on my first attempt though after trying to recreate additional sensors given the small amount of gypsum between the sensor and the probes were so thin it was extremely easy to crack the sensor and I normally have about a 25% success rate on later creations (must have had beginners luck on the first one.
The second issue was durability. Given we are playing with gypsum and as it is suspended in water it will eventually breakdown and there is very little we can do about it. Though with my latest changes to my automated grow box which includes automated watering based on moisture content I want to ensure my measurements stay accurate throughout the season. To help with this I have decided to increase the sensors size and also am using galvanized nails to prevent rusting. After a few attempts I have come up what I feel is a pretty foolproof method of creating a moisture sensor.
How it works:
There were many questions in the comments in the previous post so hopefully I can clear this up a little here.
Technically a gypsum block measures soil water tension. When the gypsum block is dry it is not possible for electricity to pass between the probes, essentially making the probe an insulator with infinite resistance.
As water is added to the problem more electrons can pass between the probes effectively reducing the amount of resistance between the problem to the point when it is fully saturated where the probe has virtually zero resistance. By using this range of values you can determine the amount of water than exists in your soil.
Parts for cheap soil moisture sensor:
- Plaster of Paris
- 2 Galvanized Finish Nails
- 1/2 inch plastic tubing
- utility knife
Construction:
Take your utility knife and cut the tubing slightly longer than your galvanized finishing nails. Try to make the cut as straight as possible though it doesn’t have to be completely perfect.
Use your utility knife to cut the smaller plastic tube lengthwise, this will allow easier removal of your soil sensor after the mold cures.
Optional: Make the cut diagonally to prevent a potential vertical fracture line.
If you were very careful on you vertical cuts you can avoid this step, but to completely avoid spilling plaster onto my workbench I drilled four holes slightly larger than your tubing. I used these holes for support but also to catch any of the plaster in the gaps from you less than accurate vertical cuts.
Being careful that the tubing fits together where you split the tubing vertically, insert the tubes into the holes (or carefully on a flat surface) Mix Plaster of Paris and carefully fill with to the top. The friction between the tubing should keep a water tight seal where you made the cut, though if the plaster is a little thin and it appears to be leaking through wait a couple minute for the plaster to setup some and try again, at that time it should not have the viscosity to seep through the very small gap that may be causing the leak.
Take your two galvanized nails and push them through a small piece of wax paper. You may also allow the plaster to setup for a few minutes and then float the nails in the the plaster. I like the first method since gravity will help ensure they fall straight down and parallel to each other. As for spacing, I have done some experimentation with the gaps between the probes and my conclusion was, it doesn’t make much difference. As long as there is a gap (they are not touching) you should get reliable results.
After allowing the sensor to cure for about and hour remove it from the holes you drilled in the wood.
Gently pull back the plastic tubing and you have a nice clean soil sensor.
Lay them out to dry for 24 hours to cure completely and their construction is complete.
For attaching the wires there are a couple options. The best would be to solder them to the probes though to do this you need to heat up the nail hot enough to enable a strong solder connection. My little 15W soldering iron just can’t produce the heat for this so I am option for the wire wrap method. I take about an inch of wire and strip off about an inch of insulation and tightly wrap around the probe. Given copper will rust and could be a point of failure you will want to insulate this connection and the probes from the moisture. A few dabs of hot glue works pretty well. I am planning on trying liquid plastic, though I am currently out and when I have some on hand I will update with how it went.
How to use your cheap soil moisture sensor
You can simply hook up a multi-meter and check the resistance though if you want to create anything automated you would need to use an integrated circuit (IC) or a electronics prototyping platform such as Arduino. By applying voltage to one side of the sensor and using a voltage splitting circuit connected to ground and an analog input you can then measure the voltage making it through the probe. The higher the voltage, the higher the moisture content of the soil.
Conclusion
The above should give you everything you need to know to create your own cheap soil moisture sensor and how to use it. This can be used as a moisture soil sensor for watering your indoor plants like I am using it. This same moisture sensor could be for monitoring your outside soil moisture content to trigger (or preempt your irrigation system) to save some money on your water bill and/or maintain consistent moisture levels in your plants which could drastically improve water sensitive crops such as tomatoes.
Tags: arduino, cheap, growbox, led, outdoor plants, tomato plants, vegetables
How to save pumpkin seeds
15.5 years ago harvest, pumpkin, seed saving, seeds
The kids and I carved several pumpkins this year but we waited carve the three pumpkins we grew in our backyard until Halloween since these were the seeds I wanted to save for planting next year. First, I know exactly how these pumpkins were grow, organically and free of any pesticides. Second, I was able to let these pumpkins grow undisturbed until the day I picked the seeds, so the seeds should definitely be mature.
The process is very simple, while getting the “goo” as my 5-year-old would say out of the pumpkin set the seeds aside and add to a colander. Give them a good rinse and remove any orange “goo” that may have snuck in. Pat dry with a towel and let the seeds dry on wax or parchment paper for a couple days. Once they are dry to touch put them layered on a paper sack and let them dry for a few weeks until putting them in homemade seed packets until the are ready for next year.
If you have way too many seeds than you need (I know I do) you can also use the great recipe to roast some of you extra seeds as a snack:
CVG’s Roasted Pumpkin Seeds
- Extra pumpkin seeds
- 1/2 tsp oil
- 1/2 tsp of Worchester sauce
- 1/4 tsp of seasoning salt
Directions: Add ingredients to bowl and mix well. Lay on a single layer on a cookie sheet and bake at 325 for about 25 minutes being sure to flip the seeds after about 10 minutes. Eat as soon as you can without burning your mouth.
Tags: cheap, garden seeds, organic vegetables, outdoor plants, vegetables
How to save corn seeds (Kernels)
15.5 years ago corn, harvest, seed saving, seeds
Corn is one of those crops I really don’t have space to grow but still like to try every year. This past year I only had one ear that made it to maturity, in the plants defense we have a very hot summer and I didn’t have the most consistent watering schedule so I am to blame for most of their demise. Given I used the last of my corn seed this year and wanting to make the best out a bad situation, I decided to use this ear for seeds for next year.
I decided to go the natural route and simply let the corn stay on the stalk until I was ready to pull up my corn stalks my wife got tired of looking at our dead corn stalks in the backyard which turned out to be yesterday (October 31st) As you can see from the picture above the corn kernels have dried out pretty well, though still contain a little moisture.
To remove the kernels I started by braking the cob in half and then starting where I split the cob pushing the loose kernels off with my thumb starting from one end to the other. Once I have this first row off it should be pretty easy to attack these kernels at any angle.
Lastly I layered the kernels in a single row in an open ended brown lunch bag to allow air flow to allow the remaining moisture to be removed. I put the bag on top of our cabinets in the kitchen and will add them to a homemade paper seed packet after a few weeks or drying (or when I remember they are up there more like a few months late) then store in the refrigerator until time for planting next year.
Now I have more seeds than I probably will ever need for a few years and hopefully will have better luck (or at least remember to water them better) next year.
Tags: cheap, garden seeds, outdoor plants, vegetables
Fuji Heavy Industries autonomous farming robot
15.5 years ago garden maintenance, robot
We have seen MIT students making robots to tend on their plants. Now Fuji Heavy Industries has created a robot that can completely take care of your fruits and vegetables in your fields (or greenhouse) for a modest fee of only $100,000. You can pick up your own by the next fiscal year.
It uses lasers with reflective panels to orient itself and is 6.5 feet long, unfortunately there are not too many additional geeky details which probably would be helpful before putting down the $100K for this bad boy.
Given this is the cheap vegetable gardener, I will be sticking with my hands and trowel next fiscal year though can’t wait to see a video if this in action.
Tags: cheap, outdoor plants, vegetables
Growing blueberries
15.5 years ago blueberry, cheap
If it were up to me every part of my landscaping would be edible. Though my homeowners association may disagree with me but blueberry bushes looks just as nice as any ornamental plant/bush when you visit the nursery with the obvious bonus of free food.
When selecting a blueberry bush, unless you are very patient spend about $10 a plant and get some more established ones (about 1/2 inch stem) You can get the two for $10 plants from your local Home Depot but you won’t be eating blueberries for a couple years. With the larger plants you should pinch off the blossoms to get better growth for the first couple years but I opt to getting my reward now instead of later and enjoy the handful of berries the young plants can produce.
When it comes to plant selection there are a large number of species to choose from with varying fruit size and harvest timing. I would recommend getting varieties that have varying maturity dates so you can enjoy those blueberries for a longer period of time. When I got my first two plants I went with Toro and Berkeley. The Berkeley is a very popular bush given it produces average size berries great for muffins/pancakes/cereal or the occasional snack with a mid-late harvest. The Toro on the other hand produces large (almost grape size) berries which are great for jams and snacks though bit of a mouthful for muffins. If you are curious of other varieties here is a great resource.
I have heard differing opinions on whether you need to have different species to successfully produce fruit after a little research I found this article which explains that blueberries are capable of pollinating with a single species, though studies have shown that having more varieties can produce larger and earlier fruits. So if you have a favorite variety you can go crazy with the single plant though a little diversity seems to always be a good thing.
When it comes to pest control the biggest pest is birds. You can control them by laying some netting on the plants, though in my personal opinion that just gets in the way of me getting my snacks so I opt for the lazy approach and just plant more plants and share with “neighbors”. Worse case I end up with a backyard with some bushes that look much nicer than my current evergreens, and I always can take up bird watching.
One of the most important parts to being successful with your little blueberry plants is soil preparation. The plants need to have an acidic soil and their roots like to remain moist, but not drowning in water. Given my area has an abundance of clay in my backyard, I naturally do not have either of these requirements. To give the plants a head start I dug a 1 foot wide/deep hole and filled it with peat moss and mixed with a few handfuls of compost. Not only will this retain water well, but the peat moss is also naturally acidic and will be a nice haven for a large family of worms in the next few years to add some awesome natural fertilizer (worm castings) Last I purchased I box of organic blueberry fertilizer which provides the primary and trace minerals as well as help keep the acidity of the soil up. I simply followed the directions on the box and watered the plants when there was a couple of days without rain.
Now some of you might be thinking, “hey it is fall why are you talking about growing blueberries” Well this is the “Cheap Vegetable Gardener, right now is a great time to visit your local nursery to pick up some of their “old overgrown” blueberry plants at bargain prices which you can plant now and enjoy some delicious berries next spring/summer.
Tags: birds, cheap, compost, led, organic vegetables, outdoor plants, vegetables, worms
Computer controlled grow box – Part 2
15.6 years ago indoor growbox, water
Though I have made some significant changes to the grow box controller, the actual grow box has undergone some minor but important changes over the past few months.
Automated watering
Now I must say this one is pretty darn simple. Though I will be planning on a slightly more complicated hydroponic setup later I decided to start with a very easy bottom watering technique. Just take a regular old fountain pump (I went with the cheapest I could find) drop it in a 5 gallon bucket of water and attach a hose long enough to reach your planting tray and plug in the power to the pump to your grow box controller and that’s about it.
To prevent evaporation and algae and little bugs making a home in my nice bucket of water, I added a lid with two holes for the water output and power input. The power input required me to make a straight cut with a utility knife to ensure a snug fit while not requiring me to cur the AC line to feed the wire through.
I also cut a hole of the same size as the water output on the bucket lid to the grow box to allow the line to enter while still keeping the box closed.
Exhaust fan control
Air circulation is important for plants to be healthy but when the box gets warmer than expected I installed two controlled CPU fans to help regulate temperate as well as one static fan that constantly pushes air from the top to bottom.
I added a 12 volt exhaust fan to the top of the box (pictured above) to help push hot air out of the grow box with another (pictured below) at the lower part of the grow box to push in cold air as needed. Both of these fans are powered by a 12 volt power wall adapter plugged into the grow box controller.
Heating
Though the computer and lights allow the box to create a comfortable internal temperature, sometimes it needs a little help. For this I installed a regular old seedling heater to hopefully take a little sting out of the cold floor the seed tray is sitting one. Like other components this was simply plugged into the grow box controller.
Putting it all together
My previous version was a little sloppily put together with duct/packing tape (lets just call it prototyping). Though this added some hackiness appear it wasn’t too functional so I added a little strip of wood to support a couple hinges which I created a top which holds the LCD panel.
Upon opening the top you can see the grow box controller and the state of the art 600 MHz PC in all their glory.
As you can see I have still have some cleaning up to do with compress air and maybe a few more zip ties but all in all everything seems to have come together nicely.
Tags: cheap, garden seeds, grow lights, growbox, led, outdoor plants, vegetables
