Commercial decompactors cost several thousand dollars and they are not all that portable. Most decompactors require additional equipment to power them and the end result is not much better than what this build can provide. The steerable units cost tens of thousands of dollars and can make quick work of a golf course green but not very practical for homeowners.
This build can be run off of a small portable air compressor, is easy to build and cost less than $200.
CLAY IS FOR POTTING
Clay is rather common throughout the mid-west and southern states. The soil is so compacted and devoid of nutrients it tends to be better suited for weeds. Lawns with high concentrations of clay soil usually have very shallow roots and lawns with any type of slope tend to shed water too quickly which leads to erosion and bare spots. If you have ever purchased a new home in a development then you have seen first hand how developers remove precious top soil and leave the homeowner with a barren wasteland in its place. Even if they lay sod down the base prevents the grass from establishing a deep root.
The only way to establish a deeper root is to break the clay down into a nutrient rich soil that promotes growth, this may occur naturally in time but most of us want a lush lawn in our lifetime. Clay amendment occurs when there is sufficient air, water and food for the microorganisms to flourish. To accelerate this decay the clay must be broken down into bite-sized portions while still providing air, water and food. Organic fertilizer is essential, wetting agents to loosen the clay is even better, decompaction makes it all happen sooner. Injecting air and water below grade loosens the compacted soil by creating voids and cracks, this improves the soils chances of retaining water.
A certain amount of clay in soil is not a bad thing. Clay has excellent water holding capabilities and can be very fertile. However, the problems of excessive clay can easily outweigh the benefits.
CLAY SOIL PROBLEMS:
Clay can be very difficult to penetrate making it hard for roots to become established.
Clay soil tends to be alkaline, which makes iron less available to plants.
Clay compacts easily reducing the amount of oxygen to the roots.
Clay can absorb and trap water for extended periods.
Clay can also cause puddling and drainage problems.
Clay can become rock hard when dried.
The material need for this build consists of only a few components. Most items can be purchased directly through my Amazon Affiliate links which I have provided for your convenience. All of the items are fairly common and can be purchased at your local hardware store.
Another side benefit to making this project is that it can easily be modified to shoot rockets and foam footballs by changing the barrel. Please follow this link to see how to turn this into a yard game.
(1) Slide Valve 1/4"
(1) Quick Exhaust
(1) Check Valve
(1) The Bimba Reservoir D-2485-A-3 ( can be replaced with a capped section of galvanized pipe)
(2) 1/4" x 2" galvanized pipe
(1) Bell Reducer 1/2" to 1/4"
(1) 1/2" "T" galvanized
(1) 1/2" Gate Valve
(1) 1/2" x 48" galvanized pipe
(1) 1/4" compressor fitting
(1) 1/4" Relief Valve (mounts on opposite end of Bimba Reservoir)
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Step 1: Theory of Operation -
HOW IT WORKS
In a nutshell, this devices creates large voids and cracks in the compacted clay soil, the voids are then filled with water, which naturally has some dissolved oxygen suspended in it, ultimately promoting root growth. Introducing an organic fertilizer during this process helps breakdown the clay into nutrient rich soil.
The water is used initially to penetrate the soil allowing the rod to bury beneath the surface, we are looking to bury the rod about 12-24” below the surface. This is accomplished by opening the water valve with the nozzle slightly above the ground, this can be very messy but it is very effective at digging. When the probe is at the desired depth close the valve, the check valve ensures that water does not enter the compressed air section.
The Slide Valve, when pulled back, charges the cylinder. When the Slide Valve is moved forward the Quick Exhaust Valve dumps the air instantaneously through the section of pipe below the surface. This rapid burst of air creates a hydraulic effect forcing the water in every direction. Repeating this process increases the size of the voids and channels until water and air seeks the least resistance, generally toward the surface. The ground will actually swell upward slightly indicating that the ground is very nearly saturated.
Full details of the operation are explained in later steps.
The blue machine (seen in photo) is several thousand dollars, my build will do a suitable job for less than $200.
Step 2: Assembly
All of the pipe thread should have a couple wraps of Teflon tape around the thread.
Lay all of the components out with the same orientation, (refer to photograph). Pay particular attention to the arrow indicating the direction of air flow. The Slide Valve, Quick Exhaust and the Check valve must have the air flow going in the same direction of the arrow as indicated on the component.
With the pipe wrench hold the Quick Exhaust Valve (QEV) securely in-place, use your free hand to thread one of the 1/4" x 2" galvanized pipes into the inlet side of the QEV then thread the Slide Valve onto the 1/4" pipe. Verify direction of air flow. Tighten the assembly with the Channel Locks.
Repeat this procedure from right to left referring to the photo above.
The Bimba Cylinder D-2485-A-3 can be swapped out with a larger reservoir. They are typically sold on Ebay. Look for a D-2485-A-6. One end of the reservoir attaches to the top of the QEV the other end has a relief valve mounted on the top to reduce the chance of an explosion. If the reservoir is too small it will have very little effect. The size of the reservoir, QEV, Slide Valve and wand will determine how effective this will be.
CAUTION: You can make quite a mess if you apply too much air at a shallow depth. I recommend starting off with a lower pressure and build up to a safe operating pressure. Using a high pressure at a shallow depth can blow a hole in the lawn.
Step 3: Complete Operation
The entire assembly is light enough to be moved around the yard. I recommend 75' of expandable garden hose to keep the weight to a minimum.
The air hose from the air compressor should also be light-weight like this "kink-free" air hose.
The secret to this entire evolution is to fracture the compacted soil around the probe, this is accomplished by dumping a large volume of air at once. My original build calls for a 1/4" Quick Exhaust Valve, swapping this out with a 1/2" QEV, or larger, will dramatically improve the performance of the unit. If you increase the size of the QEV with 1/2" than you should increase the Slide Valve to 1/2" (inlet and outlet).
Connect the compressed air and water supply to the device. Turn on the supply of water to the device and set your compressor output to a safe setting, 60 psi is quite safe provided the wand is at least 24" deep.
CAUTION: The sudden blast of compressed air can dislodge small rocks and debris. I recommend wearing safety glasses and a face shield. Avoid discharging the air through the nozzle when it is not below the ground.
Locate a section of the lawn you want to treat. It is worth mentioning that installing a flat rubber shield or flat plate on the shaft will cut down on the amount of water and debris that will be propelled your way. I have actually launched earthworms several inches out of their holes.
Place the nozzle in contact with the surface of the lawn and open the water valve. Slowly move the wand up and down while applying slight downward pressure. If you encounter a rock or a heavy concentration of heavy gravel move to another location.
Continue to bury the wand until the nozzle is about 12-24" deep. Close off the water valve. Make sure the rubber plate or shield is in contact with the lawn.
Pull the Slide Valve back to charge the Bimba Reservoir. Hold the assembly firmly in-place and then move the Slide Valve back to the forward position. The sudden burst of air will force the water away from the hole. Cycle the Slide Valve several times. The unit will recoil from the sudden burst of air, be sure that you are always holding the unit with both hands.
Next, open the water valve again to allow water to flow to the newly formed holes and channels. Close the water valve and give the ground several more blasts of air.
Each time you fill the voids with water and force compressed air into the hole, it forces the water in every direction to new voids and channels. Because water does not compress it is forced to seek the path of least resistance.
When the surface of the lawn begins to rise slightly under air pressure you can move on to another area. I have found that I can break up about a 6' diameter area. Your results may vary.
Step 4: Speeding Things Up
A SLOW PROCESS
This is a slow process and it can take several hours to work a section of the lawn but the end result is worth it. The idea is to make the surface of the lawn more absorbent allowing water to absorb into the lawn rather than run off too quickly.
The other benefit of injecting air and water below grade is that it increases the dissolved oxygen which eventually amends the clay converting it to nutrient rich soil.
Using a chemical injector in-line with the garden hose can accelerate the process if a suitable organic material is applied. Clay becomes nutrient rich soil when there is a sufficient amount of air, water and food available. Injecting an organic below grade is even more effective because there is far less product loss due to evaporation.
Injecting air, water and fertilizer during drought conditions is also a good practice.
THE MAGIC BULLET
There is a product called “Penterra” that is considered to be the fastest soil wetting agent on the market. This video is the best way of demonstrating the effect a “wetting agent” has on soil, it illustrates how even dry soil repels water.
Decrease surface tension between water, soil and plant
Improve,growth and activity of Micro-organisms
Allows water and oxygen to reach plant roots
Extremely fast, economical, and Environmentally friendly
Loosens hard clay soil, aggregates sandy soils, and reduces plant stress
An alternative to building a solid decompactor would be to simply to inject a wetting agent beneath the surface using a Deep Root Irrigator and an injector for the wetting agent. This alone will help to break up the clay soil. Spraying wetting agents on the surface tends to evaporate quickly, by inject product beneath the soil it goes to directly to the roots.
Tips & Techniques:
Here is a technique I used for my backyard to cover a larger area. I constructed 4 or 5 wands with a 1/2 union on one end of each section and I attached a Union on the end of the decompactor. I drove each wand about 6-8’ apart in the ground using an impact drill and mallet with both halves of the union assembled. I then removed the top half of the union of each wand and then placed the decompactor on each wand. I then worked each section until the ground was completely flooded. I cannot say wether this is an effective method, but it did allow me to connect the voids in a given area.
Step 5: Coming Soon
I will be submitting an instructable in a few weeks that will detail the construction of a wheeled unit. Not only will it be less cumbersome it will also include a pneumatic powered ram to drive the wand into the ground. The bottom of the dolly will serve as a splash guard and it will have additional features that more closely emulate the larger steerable units.