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Grid Sample & Data Wizards
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GOOSEPILOT
Posted 2/4/2019 23:21 (#7297640 - in reply to #7296754)
Subject: RE: Grid Sample & Data Wizards


WC Mn/Dakotas
paul the original - 2/4/2019 16:36

I’m puzzled too to understand what that 1/4 acre deal means exactly, how to apply it.

It means that when the computer interpolates the data between sample points, anything farther apart than 100ft have virtually no correlation. It is often not accurately representing tje soil spatially. So your introducing (forcing) values that are in error.

I don’t believe we are at a technological or cost point to where any farmer will grid sample on 1/4 acre grids. It just isn’t done anywhere commercially.

Exactly, it is not practical. Then often to compensate, samplers take less cores and poorer depth consistency, which only leads to more errors.

And their 1/4 acre sample size is so small it must apply to zone sampling as well!

Zone is not perfect either, but it takes into account the natural variation spatially (not forcing a "zone" into a square grid). It allows the sampler time to take higher numbers of cores and quality cores. Its making assumptions but that is where highly accurate and detailed zones come in. (Quick and easy zones often fail). Also i can sample every year for the same cost as grid every 4 years. So where alot can happen in 4 years, i can see and make accurate corrections every year if needed rather than assume each year actually goes as planned for 4 years before a correction. Then when a correction is needed in grid, how do you determine what was the cause and from which year?

Iowa is probably credited with developing grids what 20 years ago?. Shortly there after, they also determined anything larger than 1 acre didnt accurately represent much.

Paul
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