Many people do not understand how when using dug up or transferred soil (and/or wood chips) it can really affect the operation (and failure/success) and metal detector responses.
Here is why:
Wood chips almost always have a negative charge. The same is true with sawdust. But soil is a wild and crazy mix of many, many elements at times, clear up to many varied and electronically (AKA positive/negative charged) apposing compounds. Chemistry 401, not 101. This study of soils and their compounds is a subject for those with a Masters in Chemistry, Soil Science, or Agriculture, N-O-T a Masters in Metal Detector usage.
View the soil like this:
A bunch of little fish with tails on one end (negative), and heads on the other end (positively charged). When grouped together in the current they usually all head the same direction in order to avoid all the dangers of any apposing or hazardous currents. They do it for safety. And they do it naturally too.
Similar reactions occur with the electrons in all the soil; Positively or negatively charged raindrops affect the soil matrix. So do introduced other compounds such as rotting (high acid, hence high positive) vegetable matter. Positive because when losing their excessive electrons they have an excess of POSITIVELY charged ions. Added compounds from introduced other minerals create an unbalance too. But after awhile, many, many years, they eventually find that the leader of the pack is a true Republican and eventually they begin to follow him or her (the POSITIVE ones) and they (the electrons) all eventually head in the same direction, just like in a bar magnet. It then becomes a Happy Day for all the little fishes.
When some joker digs them all up and disturbs their order and their place in with the rest of their good fellows - while they all had order and were enjoying good times - they AND their other Constituents in the remaining soil get all turned around and confused, no longer having a place in the pack. There is mayhem and disorder beyond compare, just like in social or political groups where everybody is given a name tag that does not belong to them. These little electron fish are now swimming around randomly with no direction like a bunch of 3 year old children dumped in the deep forest and lost, and they REALLY get messed up when someone introduces a current or charge or magnetic field in them alongside of it all. These little children's or little electron's or little fish's electrical conductivity becomes pish-poor at best. There is no longer any linearity, no direction. And without magnetically and electrically charged positive/negative heading direction they cannot conduct electricity very well at all, and in fact defeat their purpose as regards to metal detecting.
This is the children's 3rd grade explanation of why "test gardens" and "test beds" and disturbed soils plantings are worse than worthless. In fact they are self-defeating and disproportionately valuable. If in doubt, try the same test I've done several times myself. Go get some soil that you found a coin in at 6" and then bring that same soil home and test it there in a plastic pot. That's the real truth to discover.
Never buy before you try. That's the best philosophy for just about anything.
And the "halo effect" only applies to iron with some very negligible and almost immeasurable affect showing with copper after decades, and brass and bronze several HUNDREDS of years later - unless some high acid or high sodium elements are introduced into the soil in the meanwhile. All the above is why objects buried a very long time are found deeper than freshly buried ones. It's because their electrons have had time to align themselves a bit, maybe even a lot.
Note: The only reasons that a Tesoro metal detector should sound off when waving your hand in front of it are for example,
1 If you just dusted yourself with iron filings or some other metalic dust.
2 If your detector has a poorly shielded cable
3 If you happened to have recently eaten a large load of arsenic
4 If you have a faulty capacitance circuit bleeding off to ground somewhere at the metal electronics housing box.
5 In case those from "the other side" are trying to reach earth.
*There are other reasons too, but a detector in good operating condition should NEVER read one's hand.
Note: Currently there are exactly Z-E-R-O instruments made that can detect the ionic properties of any electronic bleed-off from a coin-sized object made of copper, brass, lead, aluminum, bronze, silver, etc. To say there are is no more than a speculation or a wish or supposition. However, there ARE instrument made which can detect the amount of FE extra electrons leaching out into the surrounding soil and those are called electro-magnetometers, some of which I have used while working for the Department of Defense when we were developing the Mark 48 nuclear/electronics torpedo systems. They are d-m expensive too.
A couple of more things (electronics engineering, of course):
Tesoro detectors use a "Tank Circuit", meaning that the circuitry utilizes a quickly discharging (collapsing) transformer or transformer circuit in front of an even faster decaying and discharging (collapsing) capacitor or capacitance circuit. This is why they recover so fast and why it is even MORE difficult for a well-operating one to give a "reading" on one's hand.
And, GROUND BALANCE CONTROLS DO NOT READ OR BALANCE "IONIC READINGS". Nor do they the same with electron readings either. In fact, they balance the difference between positive and negative voltage readings (amounts), and nothing more. In fact, they and discrimination controls are the same thing, one crude, the other fine-adjustment.
This really is all fun, but Stellar Physics is even more fun.
Time for some good coffee and some even better chocolate chip cookies.
Hope this helped
LuckyLarry
lol! what are you.........a scientist!! 
.............he did ask for proof! lol 
)![:-\](https://www.treasurenet.com/smilies/undecided.gif "Undecided :-\")
