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lbedord
Contributor

Grid sampling

"Grid sampling is dead," says Dr. David Franzen, North Dakota State University. "If you want to do it right, do zones."

Do you agree or disagree?
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23 Replies
ECIN
Senior Advisor

Re: Grid sampling

Agree

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Slim123
Senior Contributor

Re: Grid sampling

Why did he say that? What was his evidence?

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Shaggy98
Senior Advisor

Re: Grid sampling

Agree, with today's GPS technology setting up zones is preferred over grids. Grids might be better than entire fields, but if your going through the effort, might as well get the most bang for your buck and go with zones.
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Jim Meade / Iowa City
Senior Advisor

Re: Grid sampling

If you use a large sample size, this may be right.  But if you use 2.5 acre grids then I don't agree.  In the first place, I don't think it is possible to define the grids all that precisely.  If you can't define them precisely, how can you define zones?  I'd rather pull 2.5 ace grids and let the zones, if any, fall out from the samples rather than try to define them from a map or by guess and by gosh.

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KSKid501
Veteran Contributor

Re: Grid sampling

If you are using precise technology like a Veris rig, zones can be extremely useful.  Unfortunately, this is still extremely slow and costly...

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Grain_Trader
Contributor

Re: Grid sampling

I wouldn't call grid dead, grid is better then flat rate IMO, but zones are better.... a mix of true removal based off of yield maps along with soil zones/test would be best, until you could rely upon removal from yield maps solely.
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idalivered
Advisor

Re: Grid sampling

agree

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Jim Meade / Iowa City
Senior Advisor

Re: Grid sampling

Maybe our pespective depends on our environment, or, as the old Indian said, what you see depends on where you stand.  In my case, I have several fields with slopes from A to E and with 3-4 soil types.  But, these soil type maps come out of a small scale book that was developed nearly 100 years ago.  Based on how I farm and what I see, I don't agree with some of the soil map entries.

 

The guy doing my soil sample tried to talk me into using zones.  I asked him how you set them up?  He said from soil types.  I said I don't trust the soil type maps.  He said from yield monitor data.  I don't have good enough yield monitor data to clearly define zones.

 

My solution was to do 2.5 acre grids with the idea that if one could overlay slope, soil type (dubious as it was) and yield (inexact so far) and something fell out of it, then maybe I could call that a zone.

 

What is the purpose of zone sampling over grid sampling if you are going to end up with the same number of generally equally spaced samples in the same field, anyway?  They both would end up doing the same thing.  It seems to me that zone sampling is only better than grid sampling if you can accurately define the zone and you use that information to reduce the number of samples you pull and therefore have a lower cost of sampling.

 

A person can use the results of a grid sample just the same as a zone sample if you are doing variable rate sampling.  Now, if you have segmetns of the field that you treat as mini-fields, like terraces or flats land or something, then zone might make some sense but it's only in the way you arrange the sample map before you pull them rather than arrange the sample map after you pull them.  In each case, you have a sample associated with a point in the field and that point doesn't move.

 

What am I missing?

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Shaggy98
Senior Advisor

Re: Grid sampling

Are your 2.5 acre grids going to be square or will they follow the contour of the land? Haven't seen to many soil maps (old or new) that shows soil types to be laid out by 2.5 acre squares. It might depend on field shape and size as well. We are only as experienced as our own operation allows us to be. In my experience with my location, we have rolling terrain with an occasional flat section thrown in here and there. I would think on the flat square parcels the grid sampling would work just fine, but on the other 90% of our land setting up zones that follow the rolling landscape would allow for more accurate precision placement. These zones once laid out are always subject to change, both shape and size. Perhaps the soil survey maps just provide us a base layer to which we can begin our zone or grid layout which ever best fits that particular field.
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