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| Thanks for the replies, guys. I'm not familiar with those particular soils, maybe I would be by name instead of the classification number. I guess when I say it's more accurate, I'm talking overall and not focusing on the individual soils.
The predominant soil types across much of northwest Iowa, particularly the areas that have the highest corn AND soybean yields, are the Primghar-Galva-Marcus-Sac soils. They are better drained than the Clarion-Nicollet-Webster series in the Des Moines lobe to the east, but they are also deep soils that can tolerate drought far better than average. If you overlay this map -
http://www.extension.iastate.edu/Documents/soils/soilregionsofiowa.... - on top of a county average yield map, you'll notice very similar yields among counties of similar soil types. Northwest Iowa, with the increase in average rainfall over the last several decades, is nearly always the top yielding reporting district in Iowa. The NW reporting district aligns quite well with the location of Primghar-Galva series. Those soils saw increases from the the 70s in the original CSR to the 90s in CSR2, which I believe is a better indication of their actual quality given the yields produced in NWIA relative to the rest of the state. | |
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Farm ground in Iowa
