What about halo efect explanation in this case

[WM6]

Hallo, hello, halo, alo?

[ivconic]

Hallo, hello, halo, alo?

That's correct fact.
Coins on freshly plowed fields are very hard targets (coins deeper than few inches).
Coins on not disturbed soil are much easier targets.
Simple facts and simple truth.

[Nandor]

I have found somewhere an article about this, it said that the soil has a ground matrix which conducts electromagnetic field but after plowing you brake this ground matrix and it isolates the targets below.

[Nandor]

Whites homepage
"Ground Matrix – Total volume of undisturbed ground, usually contains varying amounts and combinations of minerals, moisture, and salt. In an undisturbed condition the ground matrix can exhibit numerous effects on metal detector performance."

[ivconic]

I have found somewhere an article about this, it said that the soil has a ground matrix which conducts electromagnetic field but after plowing you brake this ground matrix and it isolates the targets below.

Actually that's very true.
I was dealing a lot with magnetometers for some time.
The very same sort of statements i founded in many articles and books on Magnetometry subjects.

[WM6]

Whites homepage
"Ground Matrix – Total volume of undisturbed ground, usually contains varying amounts and combinations of minerals, moisture, and salt. In an undisturbed condition the ground matrix can exhibit numerous effects on metal detector performance."

OK. But in present case we have two layers.
Only top layer is disturbed ground by plowing.
Bottom layer, where coin is located, remain intact and soil around coil undisturbed.
So "halo effect" should remain intact too, along with detecting depth, but is not.

Knowing lazy detectorist (me), who avoid to dig week signal which, by past experience,
lies deeper than 30cm. On pretty productive nearby piece of farmland he regularly
perform detecting exercises. When field is unplowed there are a lot of deep weak signals.
After plowing all such signals disappear and appear again after soil at rest 1/2 year or so.

[ivconic]

OK. But in present case we have two layers.
Only top layer is disturbed ground by plowing.
Bottom layer, where coin is located, remain intact and soil around coil undisturbed.
So "halo effect" should remain intact too, along with detecting depth, but is not.
Knowing lazy detectorist (me), who avoid to dig week signal which, by past experience,
lies deeper than 30cm. On pretty productive nearby piece of farmland he regularly
perform detecting exercises. When field is unplowed there are a lot of deep weak signals.
After plowing all such signals disappear and appear again after soil at rest 1/2 year or so.

Interesting observation.
But obviously (past experience too) plowed layer is somehow presenting obstacle even when in lower layer there is "hallo" effect presented.
I guess it's because of the dispersive nature of plowed layer.

[homefire]

Anyone who has been detecting for some time knows about that wonderful target you dig up only to have it disappear. A bit of Iron or other metals that have disintegrated to nothing but ions left in the ground.

[Koala]

I haven't noticed any halo affect on anything other than iron. If working in all metal mode you can remove iron and still have a response to the ground. Threshold changes even after target removed. I don't get any response after remove a copper artefact even if there is a green stain in the ground. Any halo will be marginal.


Dug soil swells by 30% so over plough ground you are up to 30% further away from your targets.




Best depth I normally get is on dry sand which is or close to air tests. All with a VLF

[Nexus]

Hallo, hello, halo, alo?

In this case most deep targets are left for the future generations. I always warn my customers to forget about depth in freshly plowed arable land. In such case not only the depth is inhibited, but also the discrimination becomes more erratic.

[Qiaozhi]

Dug soil swells by 30% so over plough ground you are up to 30% further away from your targets.

I was about to suggest that, but you beat me to it.

[Nandor]

From Tesoro's site, pretty interesting.
"My detector still finds large iron targets, even with the Discriminate set high. Is this normal?
.......Large rusty iron can also give off signals no matter where the discrimination is set. When iron or any ferrous target is in the ground long enough, it starts to rust and break down. This causes a large halo of super mineralized dirt around the target. The halo is different enough from the surrounding ground matrix that the detector picks up a signal. The strength of the signal is so large that it momentarily overdrives the detector and it beeps. Signals of this nature usually seem bigger than the size of the coil.The best thing to do when getting either a broken signal or a very large signal is to dig the target. Most of the time, it will probably be junk, but every now and then, you will be happily surprised by a very unique target."

This happened to me. We were detecting with my friend and he's White's gave a massive signal he said it must be very large! it was like a car was underground signal everywhere! I started to dig, we have found an old hammer very rusty probaly smith's hammer.

[WM6]

Problem is, that "large rusty iron" retain more or less equal sustainable detecting distance/"depth" (along with high reading unstable VDI)
in air test check after dig, while silver coin target not (its air test after dig distance shorten in comparison to its depth in soil after dig).

I think, real halo effect phenomenon we can find with pieces of noble metals and not so much with "large rusty iron" where changes in
detecting depth/distance are not so distinctive.