Test Garden

[sparkydog]

I'm thinking of "seeding" A clean area of my yard with various targets and trash to test detector settings for depth, recovery from trash nulls and ground tracking speed. It seemed simple enough at first but I have a ton of questions arrising as I consider what targets to plant at what depth and how far from my zip tabs, foil and nails. To further complicate matters I want to create sections of high mineralzation using both magnetic and non-magnetic black sand I brought home from my sluicing out west. Has anyone done this or given much thought on how best to create a serious test-bed which would yeild some good insights into the difference between different detectors in different set-up configurations? I'd appreciate any inputs that I could incorporate into a "plot plan". I would like to avoid reduntent situations or omissions while really wringing out various machines and learning how to optomize their settings for various conditions. Before adding my black sand "mineralization", the soil will be loamy, Pa. garden soil with a little clay down deeper. A layer of sand and rock salt is not out of the question and my targets will be clads, silver and even a couple of gold nuggets and pickers in plastic bags.

 

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[cudamark]

I made one many years ago at my old place. If you have the room, place the targets in rows at least 3' apart and at various depths. Keep in mind that it will take many years for it to be an accurate measure of the real world of hunting. Adding a little fertilizer around the target will help accelerate the process as it will attack the metal and cause it to decompose quicker. This is for hunting areas like schools and parks that use fertilizer. If the area you're going to hunt has very little of that, you may not need much to simulate those conditions and the test garden will probably be accurate sooner. There are so many soil conditions that it's hard to say for sure. Good Luck!

 

[TerryC]

Your efforts will be well rewarded in experience. Many build test gardens. I don't have a TG but I'll tell you what I do. I put targets into plastic lamination. Gold, pull tab, aluminum, lead, etc. By putting it in lamination, I can "change" the garden to virtually infinite set-ups. I can pair a silver dime with a nail.... move the nail below or above the dime. Put a piece of aluminum next to a penny (copper or zinc) then pull the strips out of the ground to set up something else. Because they are in a plastic strip, I can easily measure exactly how deep I am putting the targets... then easily pull them out to setup something else. No system is perfect. Nor is the standard TG. Here is another suggestion for your blacksand setup. Using epoxy, make blacksand "pies" in paper cupcake forms. Then you can control the amount of "mineralization" in the ground. Take care. TTC

 

[Frankn]

Actually, I don't like test gardens. With a detector you have 2 things to consider, distance to target and material of target, so why introduce another factor? That is the infinite variation of ground interference. It is unlikely that the ground that you hunt is exactly the same as a test garden, so why bother. It is far better to air test. In my younger days of metal detecting I built a stand that held a target and the coil. I could adjust the height of the coil above the target and slide the coil back and forth to simulate scanning.
I must note that there is at least one brand of detector that will not air test properly. This brand boost the return signal in certain types of soil. This means it will pick up deeper than in air tests in some soils, but also means that it will false more easily. Frank

 

[spartacus53]

Just dig everything and remember. "Garden, you don't need no stinkin garden"

 

[cudamark]

A test garden isn't an exact science but it helps you compare different detectors on different targets under various conditions. You can soak your garden or let it completely dry out to see what the targets read so you can use whatever detector you need for the conditions you anticipate in the hunt. Just another bit of information to help you decide, not the only or final word.

 

[leaker]

Thanks for asking the same question I was going to ask minus the black sand. I have not done so good on my last two outings so something is going to change. Be nice to the deputy they decide were you will sleep tonight.

 

[sparkydog]

Thanks for the input. Interesting thoughts on the fertilizer issue. My best guess is that fertilizer would cause more rapid oxidation of target metals and the asspciated mineralization of the surrounding area would make them easier to detect than a "clean" surrounding background such as would accompany a recently buried item.

 

[sparkydog]

Thanks for your reply. Your suggestions are really quite insightful and I may try to incorporate them into my TG. I had planned to put my junk targets next to good ones at different distances to test recovery time but it hadn't occured to me to put them over or under to test the masking effect. I'm still not too sure about the black sand and just how I'll disperse it since most soils usually have only a few pinches of it in a bucket of material. Those "cupcakes" might be a bit unatural if they are too dense. Thanks again, I'll post my results soon if the ground doesn't freeze before I get this project completed.

 

[sparkydog]

Well Frankn, I do appreciate you responding to my TG question but I gotta admit you threw me for a bit. I noted you have over 4K posts and nearly 200 likes so I went and read a bunch of your posts to get some idea of where you're coming from. I think I get you a little better now. None of my targets have ever been in the air. They are all in the ground which you noted is always variable. Each of my detectors accomodate this in one way or another and to a lesser or greater extent afford me a means of adjusting them to deal with differences to gain best depth and function. Until I start searching for targets in the air I'm going to have to consider air testing BS. hehehe Thanks for you're input man.

 

[sparkydog]

To dig everything you gotta find everything so I want to hone my skills at using my detectors at their optimum setting for a given condition so I dont miss my opportunity to dig.

 

[sparkydog]

When I get this thing set up, I'll use it awhile and report whether it has been useful and what I've learned. My machines themselves have taught me alot in 13 years of hunting but the more I learn, the more I realize I don't know yet!

 

[sparkydog]

Hi Terry, the ground here in Pa. is soggy just now and will likely freeze before it can dry out a little. Looking for alternative test gardens, I went to the you tube app on the tv and found an elegant alternative to digging up the yard. A guy made a wooden box a little more than a foot deep, about 18 inches wide and a few feet long. He drilled holes the right size to accept 1 inch pvc tubing opposite each other across the box. They are stepped in one inch increments starting shallow and progressing down to about a foot. After putting a length of pvc through each pair, he filled the box with soil typical of his hunting conditions (Arizona in his case). He uses a 1 inch square stick with a slot in the end to hold his test target and sticks it through the tubes at progressively deeper positions while running his coil above the box. He can use the slot or put the coin on the top or bottom of the stick to get fractional increments. He can also rotate it 90 degrees to simulate a flat coin or one on edge.
All in all a prettu slick set-up.

 

[cudamark]

How is this different than an air test?

 

[sparkydog]

An airtest penetrates nothing so IMHO is just about useless. While this test box may not be a perfect representation of the real earth, it does make the signal penetrate soil and deal with mineralization.
Just based on your listed detectors, I have to believe you're just playing "devil's advocate" with that post.
I have an SL90 and use it all the time as my coin and jewelry machine. Do you still use yours? I got all the books and the DVD with mine when I picked it up about a year old in '91. Even got Jimmy Seirra's engineering notes and his book on prospecting with the SL90. Never did much with the prospecting info though, bought a GMT instead for that.

 

[cudamark]

I guess I didn't quite picture the test box accurately. I was thinking that the PVC was installed vertically and the targets were lower down into the holes with the soil surrounding them. That would be no better than an air test. After re-reading the description a few times, I think it's set up where the PVC tubes are mounted horizontally and at various depths under the soil. That way it would at least introduce some mineralization interference. If a tube was installed on a slant, you could get very precise on depth. It will only be accurate in the type soil you chose to use and the target is still virgin, with no interaction with the soil for the years needed to simulate real conditions. Good thought and better than just an air test.
Yes, I still use the SL90. It's a great machine. I've used the prospecting mode a couple of times but haven't found any gold with it. I just needed a little more depth so I got the E-trac. The E-trac is MUCH better in the wet sand at the beach too.

 

[Frankn]

Well here is how I look at it. The air test tells you what you can pick up, What it reads on your screen, and how far away you can pick it up and it's easy to do and requires no extra questionable work. The ground is a constantly changing factor from place to place and wet to dry spell so why introduce a questionable factor to muddy up the equation. The ground is canceled out when you ground balance anyway! Make it easy on yourself! Frank

 

[cudamark]

Because if you're comparing detectors, some models work better in soil than air....other work better in air than soil. Ground balancing just tells the detector what the current ground is like but it doesn't just ignore the ground like it wasn't there.

 

[Frankn]

Cudamark, It sure does ignore it like it wasn't there! If your detector senses that the ground is returning 5% of the transmitted signal, well it just subtracts 5% from the returned reading. What did you think it did with that info?
Now I admit that there are brands that might only subtract say 4% in hopes of picking up deeper, but this leads to false signals. Frank

 

[cudamark]

If it ignored ground mineralization like it wasn't there, an air test and ground test would give the same results. In the ground balancing process on many detectors, you'd hold the coil up in the air so there was no ground interference at all while you pressed on button, then lower the coil to the ground a press another button so the detector would now see the difference between the two and not beep on that difference. You can say it "ignores" the ground mineralization if you like but it really just avoids beeping because of it. The mineralization is still there and effects the operation of the detector in depth and target ID. Some machines do it better than others depending on the type of mineraization.