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| That's the problem with grid sampling, Steve. They take a few cores in a 5 ft. area and then step up or down between each sample, not knowing what is in between each sample. Like Hay Wilson said, you can take two samples within a few feet of each other and get different results. You have to average the data at some point, but averaging 5 acres using a 5 sq. ft. sample is not the way to do it.
This year, I printed off 6 years of yield data and sat down to see if yield zones would work. When you look at each map side by side, I was amazed to see how there was very little correlation between zones year in and year out. Most of the fields were highly variable and depended on the weather for that year. Dry years seemed to pick out the soil types much better than wet years, but the same field in a wet vs. dry year looked completely different.
So I decided that yield zones weren't going to work. Or at least not for the 40 or so fields I tried it on. Wouldn't a VERIS machine just make a map that is real close to a yield map anyway? Not sure I could justify $15,000+ for one trip over the field. I'm experimenting with high res (6 in. and 1 ft. pixels) aerial photos and tweaking soil maps off those. | |
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Grid vs Zone
