Recently Plowed Field Impact on Detector Signals?

AirmetTango

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I'm pretty new to metal detecting (almost two full hunt seasons now) and even more noobish when it comes to detecting farm fields - I only started hunting fields this year. I got my first field permission in the late winter, and hunted the heck out of it until the crops were planted. I was also fortunate to be able to hunt a couple other fields in the Spring. In the process, I learned a few things - signals in a field are definitely less consistent than yards and parks. Mineralization seems to be a greater factor, plus these field sites are ghost towns, so iron is everywhere. Signals were less solid, depth was curtailed, and many plugs would get turned only to find that the signal disappeared. Be that as it may, I got used to the differences between fields and yards pretty quickly and had some very successful and enjoyable hunts. And once the crops were planted, I was immediately looking forward to the fall harvest to get back out there!

So now it's fall, and my original field permission has been chisel plowed. I hunted it for the first time since Spring earlier this week, and I was amazed at the difference in signal quality. Very little was even remotely repeatable, unless it was large or within an inch or two of the surface - a major difference compared to earlier in the year. I made a few coin finds there this week, but two were close to the surface. One was in the 3-4" inch range, but it was the kind of signal that if it were a yard, I'd likely never dig it.

Here's the real interesting example: in the Spring at this field, I found four big, solid brass spheres across several hunts. They varied slightly in size, but each was found at about the 4-6" range, and each one was an obvious "dig me". Absolute solid signal in all directions in the low 90s...I was sure I had an awesome coin each time, and each time they were easily the best signals I ever got in the field. Yesterday, after the chisel plow, I got over an extremely rough signal. The signal varied in every direction, sometimes high tone, sometimes mid tone, but never less than 40 or so on the VDI. It truly sounded like junk...the only thing exceptional about the signal was that it was one of the very few that didn't go iron in at least one direction, or worse, just disappear. So I dug it, and to my surprise, 5" down I pull out a brass sphere just like those great sounding targets from Spring. Granted, once I got 3" of soil off the top, the signal had cleared up to solid upper 80s - but initially, the same target type in the same field at the same depth suddenly sounded like absolute junk instead of an insanely good target.

Anyway, all this got me to thinking - what the heck has caused the signals in this field to all turn to junk?? Is this what experienced field hunters deal with on a regular basis? Does a chisel plow introduce so many air pockets and disrupt target halos enough to do this? Do I need to wait and give the ground a chance to settle down and compact again? Or just get used to digging even crappier signals?
 
Here’s an image of the brass spheres I’m talking about. The one found this week is at the bottom to the left of the quarter (for scale):
 

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Yep field hunting is a whole different animal. You have to dig it all. Freshly plowed fields are especially tough. A soaking rain will help
 
...Freshly plowed fields are especially tough. A soaking rain will help

Thanks - we’re currently getting dumped on right now...hopefully that’ll help! Should also rinse off some dirt and reveal some new eyeball finds. It’s the kind of site where bottle shards, bricks, and ceramic is littered everywhere. I picked a Buff, porcelain buttons, all kinds of neat stuff right off the surface in the Spring.
 
When I first started detecting I buried some coins at measured distances to see how my machine reacted to each of them. I thought that I had wasted my money when I had real difficulty getting a signal from quarters that were 5-6 inches deep. I asked some questions and was told that some machines do not work well at all in disturbed soil. After a good soaking rain and the dirt had time to settle the depth that I could find the coins improved greatly.
 
Unsure what you mean by "less consistent"? Unless you mean more junk signals? Which would be the case if your research was correct, and you were hunting an actual old homesite.

You need to consider all that was there at one time, which didn't get hauled-out in the event of a move, or abandoning the home. Fires were common as well. Nails, little bits of cans, trash piles, building hardware (hinges, knobs/pulls, hangers, etc), lead was a common use item, then there's barn contents...horse tack, tools, and loads of other junk.

Keep in mind, there was no trash pick-up, so everything was disposed of on property. All those nails....dissolve into a spot of rust that falls apart and disappears when you dig it.

Mineralization is a geographical thing, not a "difference between a field and a yard" thing. If a yard has high mineral content, the field next to it will as well. If you think it's mineral....switch to all metal, and you'll note it's likely (junk) targets, not minerals, making your detector act that way. Or, you may not be properly GBing.

I've found lots of goodies by digging poor/iffy/bad/junk signals, it's part of the game. When there's so much junk in the ground, it makes it harder sometimes to get a clear "dig here" signal when junk and a coin are in the same hole. Why I've said many times, regardless of what you use....there's only 1 way to be 100% certain of what's under the coil.

Plowing has nothing to do with anything, other than making it a PITA to walk on, and harder to consistently keep the coil level over rough dirt. It just seems to me that you're not used to hunting in the midst of all that junk. Just stick with it, and if you're in an area producing finds, slow-down. Get a long handled shovel to save from stooping at every target you dig, and dig the iffy signals. I can kick around in the dirt I'd flopped out of the hole, and many times never have to bend over, unless it's to pick something up.

Yes, you'll dig a lot of junk, but you'll end-up with more keepers too.
 
Unsure what you mean by "less consistent"? Unless you mean more junk signals? Which would be the case if your research was correct, and you were hunting an actual old homesite.

You need to consider all that was there at one time, which didn't get hauled-out in the event of a move, or abandoning the home...

Sorry for my poor descriptions, Gauntlet. No, I don't mean more junk signals. Maybe I'm trying to say "junked up signals". The research is correct - it isn't an old homesite, it was an entire town. There is almost no such thing as a traditional, solid "that's a dime at 5 inches" signal. Everything, trash or good target, is skewed by the proximity of junk, debris, etc unless it's large or very close to the surface. Maybe I need to drag a magnet across the site and see what attaches to it...I'm sure I'd get iron down to the size of grains of sand. I usually hunt the site using my 5x8 coil to help minimize the issue.

Anyway, by "less consistent" or "junked up", I mean that I can swing over a target and get a mixed tone, high and mid, say 80 one direction, then 53 the other way if you look at the numbers. Try again with the same orientation, 63 and 42, all mid tone. And another swing, 49 and 56. Turn 90 degrees, get a high tone one way, say 75, and the signal disappears or is in the disced iron range the other. Dig the target, and it's an Indian at 4 inches (actual experience last hunt). Or it's a melted slug of lead. Or an unidentifiable bit of metal. Or it's a sliver of a harmonica reed. Or it's the remains of a square nail. On a yard, that same Indian would likely be a solid 70-72 in all directions at 4", assuming it wasn't junked up or masked. And what I'm trying to get at, is the Indians and other targets I found on this site earlier in the year sounded "less consistent" or "junkier" than at a yard, but much better than everything I've heard and/or dug this week at the field.

Mineralization is a geographical thing, not a "difference between a field and a yard" thing. If a yard has high mineral content, the field next to it will as well. If you think it's mineral....switch to all metal, and you'll note it's likely (junk) targets, not minerals, making your detector act that way. Or, you may not be properly GBing.

I was under the impression that certain fertilizers and other crop chems can potentially impact the mineralization of the immediate area of a farm field versus a yard in town - that's not true? I'm just a city boy, so I'm clueless about what's actually in most crop treatments.

Granted, I might not be precisely ground balanced - it is extremely difficult to find a spot to perform an auto GB in this field, and I doubt my skill level is high enough yet to adequately do it manually. Plus the GB undoubtedly changes across the field - I rebalance frequently on this and other sites. But I'm not GBing any different now than when I was hunting the site earlier in the year.

Plowing has nothing to do with anything, other than making it a PITA to walk on, and harder to consistently keep the coil level over rough dirt. It just seems to me that you're not used to hunting in the midst of all that junk.

Partially true - I do have to reacquaint myself with hunting amidst the sheer quantity of junk present at this particular site after spending several months on "easier" grounds. But what I was trying to express is that I'm perceiving a very noticeable change compared to when I hunted the site earlier this year. I easily spent well over a hundred hours on the site from March to May and made many excellent finds - it was challenging, but I managed pretty well. Now - the same site, same equipment, same detectorist, and I'm noticing that the targets I'm getting over sound very poor compared to similar targets dug earlier this year. The only difference I see is the chisel plow - so I was hoping there was a correlation. I don't see it as "not being used to it", as I'm just comparing it to what I remember on the same site that I've spent a lot of time on.
 
Thanks for this discussion. The fields around here are getting plowed, but I don't think any of them near me have any history with old homesites. I need to do more research.
 
What detector are you using? I hadn't seen mention of it anywhere (sorry), not that I could offer specific advice, but someone hunting with the same MD might have something to offer.

Sorry for my poor descriptions, Gauntlet. No, I don't mean more junk signals. Maybe I'm trying to say "junked up signals". The research is correct - it isn't an old homesite, it was an entire town. There is almost no such thing as a traditional, solid "that's a dime at 5 inches" signal. Everything, trash or good target, is skewed by the proximity of junk, debris, etc unless it's large or very close to the surface. Maybe I need to drag a magnet across the site and see what attaches to it...I'm sure I'd get iron down to the size of grains of sand. I usually hunt the site using my 5x8 coil to help minimize the issue.

Almost sounds like an equipment issue?


Anyway, by "less consistent" or "junked up", I mean that I can swing over a target and get a mixed tone, high and mid, say 80 one direction, then 53 the other way if you look at the numbers. Try again with the same orientation, 63 and 42, all mid tone. And another swing, 49 and 56. Turn 90 degrees, get a high tone one way, say 75, and the signal disappears or is in the disced iron range the other. Dig the target, and it's an Indian at 4 inches (actual experience last hunt). Or it's a melted slug of lead. Or an unidentifiable bit of metal. Or it's a sliver of a harmonica reed. Or it's the remains of a square nail. On a yard, that same Indian would likely be a solid 70-72 in all directions at 4", assuming it wasn't junked up or masked. And what I'm trying to get at, is the Indians and other targets I found on this site earlier in the year sounded "less consistent" or "junkier" than at a yard, but much better than everything I've heard and/or dug this week at the field.

IH's can give odd signals, so I wouldn't base much there. I've dug many that were flat-out junk signals.



I was under the impression that certain fertilizers and other crop chems can potentially impact the mineralization of the immediate area of a farm field versus a yard in town - that's not true? I'm just a city boy, so I'm clueless about what's actually in most crop treatments.

Something I've never encountered/heard of. I know it (fertilizer) can help in making what could have been a good find into a not so good find, lol.


Granted, I might not be precisely ground balanced - it is extremely difficult to find a spot to perform an auto GB in this field, and I doubt my skill level is high enough yet to adequately do it manually. Plus the GB undoubtedly changes across the field - I rebalance frequently on this and other sites. But I'm not GBing any different now than when I was hunting the site earlier in the year.

Then I'd "clean out" an area to GB in, to prevent attempting it over who knows what.


Partially true - I do have to reacquaint myself with hunting amidst the sheer quantity of junk present at this particular site after spending several months on "easier" grounds. But what I was trying to express is that I'm perceiving a very noticeable change compared to when I hunted the site earlier this year. I easily spent well over a hundred hours on the site from March to May and made many excellent finds - it was challenging, but I managed pretty well. Now - the same site, same equipment, same detectorist, and I'm noticing that the targets I'm getting over sound very poor compared to similar targets dug earlier this year. The only difference I see is the chisel plow - so I was hoping there was a correlation. I don't see it as "not being used to it", as I'm just comparing it to what I remember on the same site that I've spent a lot of time on.

The odd part is you've hunted the same area prior, with no issues, and again, it leads me to think equipment issue(s).

Have you tried a different coil (I saw you'd made mention of another coil), or lowering sensitivity?
 
Thanks for this discussion. The fields around here are getting plowed, but I don't think any of them near me have any history with old homesites. I need to do more research.

If you're allowed access, look for the high spots in the field, walk it looking for evidence (glass, pottery shards, etc). Of course plat maps are the best source, and something to do when the weather is less than cooperative.
 
What detector are you using? I hadn't seen mention of it anywhere (sorry), not that I could offer specific advice, but someone hunting with the same MD might have something to offer.

Using an ATMax - I probably should have included that!


IH's can give odd signals, so I wouldn't base much there. I've dug many that were flat-out junk signals.

Very true! :lol: Those alone probably wouldn’t have concerned me...but when that brass sphere rang up like absolute junk, that was a major “what the...” moment.


Something I've never encountered/heard of. I know it (fertilizer) can help in making what could have been a good find into a not so good find, lol.

Ok, good to know - I certainly couldn’t quote a source for where I was getting that from, so thanks for dispelling a weird myth I had floating in my head! :lol: But yeah, we’ve certainly all seen what a good dose of fertilizer will do to an otherwise beautiful coin!


Then I'd "clean out" an area to GB in, to prevent attempting it over who knows what.

Simple solution - thanks! Kind of foolish that I didn’t think of that myself.

Almost sounds like an equipment issue?

he odd part is you've hunted the same area prior, with no issues, and again, it leads me to think equipment issue(s).

Have you tried a different coil (I saw you'd made mention of another coil), or lowering sensitivity?

I can definitely see how it could look like an equipment issue - maybe something that cropped up since my previous hunts, but I don’t think so. I checked connections, did a factory reset, no apparent EMI - so the basics are ruled out. I’ve tried the 5x8 and the stock 8.5x11 - I saw some improvement using the smaller coil, but not much. More importantly, I get expected performance from the detector at other locations, including other fields that weren’t plowed, just harvested. In fact, yesterday I dug a Barber dime at this field location about 5” down that had a beautiful tone...but I was in a grassy area near the field that hadn’t gotten plowed. I have lowered the sensitivity, first to 6 out of 8 bars, then 4 out 8 bars. I didn’t try any lower than that - otherwise I figured I may as well hunt with my pinpointer :lol: And I didn’t stay there long for fear I was missing stuff, so I bounced it back up to 5 bars. But maybe I need to experiment at that lower sensitivity a little longer. Still, that wasn’t necessary earlier in the year...:?:

Thanks for the ideas and suggestions, Gauntlet - I really appreciate it. I don’t mean to sound like I’m shooting them all down. I’m just genuinely trying to think through what I’m experiencing and trying to match it to what more experienced detectorists are telling me. You’ve given me some excellent food for thought - I’ll certainly be hitting that field some more, and I’ll try making some adjustments based on your input!
 
Don't know about your mechanical/trash/whatever issue you have, but I have found those same type brass balls - at the site of a blown-up Confederate gun powder mill. Those balls were used to grind the powder. Brass didn't cause sparks! You are on an interesting site.
 
I am jealous of you guys that hunt fields that are plowed. I hunt fields that had military camps in 1898 and have been "no till" for 20 years. I know there are great things that were plowed under many years ago that are nearly impossible to detect. I know the plow used last turned 12 to 14 inches, add a bit of uneven ground and bean stubble and those cuff buttons and trimes are beyond detection. I may be in luck this year because they are going to reshape some areas and that may expose some things. I know there is stuff deeper because one field that had a camp in now a construction site and we found more stuff after they scraped some topsoil off. Be happy to put up with those different kind of signals, at least there are signals there!
 
Using an ATMax - I probably should have included that!

Not a problem (might add it to your sig, for future similar issues).

Very true! :lol: Those alone probably wouldn’t have concerned me...but when that brass sphere rang up like absolute junk, that was a major “what the...” moment.

Well, there are no "absolutes" with detectors, none are 100% accurate all the time.

Ok, good to know - I certainly couldn’t quote a source for where I was getting that from, so thanks for dispelling a weird myth I had floating in my head! :lol: But yeah, we’ve certainly all seen what a good dose of fertilizer will do to an otherwise beautiful coin!

I'm not saying in certainty, just I'd never heard/had issues with it.

Simple solution - thanks! Kind of foolish that I didn’t think of that myself.

lol, always easier being outside looking in, especially once frustration enters the picture.

I can definitely see how it could look like an equipment issue - maybe something that cropped up since my previous hunts, but I don’t think so. I checked connections, did a factory reset, no apparent EMI - so the basics are ruled out. I’ve tried the 5x8 and the stock 8.5x11 - I saw some improvement using the smaller coil, but not much. More importantly, I get expected performance from the detector at other locations, including other fields that weren’t plowed, just harvested. In fact, yesterday I dug a Barber dime at this field location about 5” down that had a beautiful tone...but I was in a grassy area near the field that hadn’t gotten plowed. I have lowered the sensitivity, first to 6 out of 8 bars, then 4 out 8 bars. I didn’t try any lower than that - otherwise I figured I may as well hunt with my pinpointer :lol: And I didn’t stay there long for fear I was missing stuff, so I bounced it back up to 5 bars. But maybe I need to experiment at that lower sensitivity a little longer. Still, that wasn’t necessary earlier in the year...:?:

I think a slight notice in swapping coils could be expected. Were you able to successfully GB at the site where you found the dime?

Next time you get a "good" signal, before digging, lower your sensitivity to get an idea how how much difference it'll make, then note the depth of the target.

Thanks for the ideas and suggestions, Gauntlet - I really appreciate it. I don’t mean to sound like I’m shooting them all down. I’m just genuinely trying to think through what I’m experiencing and trying to match it to what more experienced detectorists are telling me. You’ve given me some excellent food for thought - I’ll certainly be hitting that field some more, and I’ll try making some adjustments based on your input!

You're welcome, and heck no...I'm just tossing ideas at ya.

I know it's one of the farmers busiest times of the year, but I'd ask him the 1st chance I got (without bothering him) if there was something "different" done in that field, between the time frame of the 2 hunts where you'd experienced the issues.

Something related, you might find interesting:

https://metaldetectingforum.com/showthread.php?t=127910

http://www.metaldetectingworld.com/positive-hot-rocks.shtml

I am jealous of you guys that hunt fields that are plowed. I hunt fields that had military camps in 1898 and have been "no till" for 20 years. I know there are great things that were plowed under many years ago that are nearly impossible to detect. I know the plow used last turned 12 to 14 inches, add a bit of uneven ground and bean stubble and those cuff buttons and trimes are beyond detection. I may be in luck this year because they are going to reshape some areas and that may expose some things. I know there is stuff deeper because one field that had a camp in now a construction site and we found more stuff after they scraped some topsoil off. Be happy to put up with those different kind of signals, at least there are signals there!

No till is what many are doing these days, and in fact the area I'm now living in/hunting is no till. lol, makes for easier walking :lol:

Consider this....what was turned 12" under one year, was turned 12" over the following ;)
 
I look in farm fields before or after being chisel plowed with no problems of running unstable.

Anyone claiming fertilizer ruins coins are wrong. I have seen coins found in fields in better shape than coins found in yards.
 
A lot of misinformation in this thread. Fertilizer definitely can effect mineralization and the condition of some finds. I guess the amount of the effects depends on location and the type and amount of fertilizer used. My ground balance numbers are ALWAYS different in a local farm field vs local yard/park and almost anything deeper than a 3-4” is going to be a choppy signal. Recently plowed fields seem to magnify this problem. Ive dug large coppers at over a foot in a local park that were crisp and clear dig me signals
 
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A lot of misinformation in this thread. Fertilizer definitely can effect mineralization and the condition of some finds. I guess the amount of the effects depends on location and the type and amount of fertilizer used. My ground balance numbers are ALWAYS different in a local farm field vs local yard/park and almost anything deeper than a 3-4” is going to be a choppy signal. Recently plowed fields seem to magnify this problem. Ive dug large coppers at over a foot in a local park that were crisp and clear dig me signals

Feel free to cite some evidence, outside of your personal opinion. I'm all for being educated.
 
I look in farm fields before or after being chisel plowed with no problems of running unstable.

Anyone claiming fertilizer ruins coins are wrong. I have seen coins found in fields in better shape than coins found in yards.

And you have a detailed history of what/how much fertilizer was used in the fields you hunt?
 
Don't know about your mechanical/trash/whatever issue you have, but I have found those same type brass balls - at the site of a blown-up Confederate gun powder mill. Those balls were used to grind the powder. Brass didn't cause sparks! You are on an interesting site.

Thanks for that info, Texaspast! I originally thought they were some sort of ball bearing for railroad equipment (there was a rail depot at the town), but brass/bronze/copper seems too soft for that type of application. Others have suggested they were milling balls too, and your info adds even more credence to the idea. I’ve found more shot shell head stamps at the site than I can count, so there may be a correlation there. Also, the town was likely associated with the oil boom in the area - so it might be more likely that someone was milling black powder to use for shooting the wells. I think they tended to use dynamite/nitroglycerin for that, but I’m pretty sure black powder was used in many cases, as well.
 
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