Iowa CSR ratings

[Jim Meade / Iowa City]

There has been an update of the Iowa soils survey, so if you want to be sure what the CSR is for your soil types you can check it out here.

http://www.extension.iastate.edu/soils/ispaid

I wish there was a good site to find soil type maps. 

[BA Deere]

The whole CSR is something that should pehaps be re-rated. As I understand it, in the 1940`s soil types were rated on the bushels of corn they would produce without fertilizer, CSR of 80 would produce 80bu/ac back then.  Well, today soil is becoming more or less a "structure that holds a plant upright".  With fertilizer, new hybrids and tile/irrigation a CSR of 40 can raise +200 yields.  I have some 40 CSR "peat"  that yrs ago the only weed control was continous corn, 12 lbs of Atrazine and 3 cultivations.  Today that peat will rock n roll with the best 90+CSRs, the only caveat is a early frost, that loss of 50 feet of altitude is hard to do anything with when it`s a freak 30º night in early September. In the past, if a brave soul planted beans in the peat, with the lack of weed control, if you could tell it was beans through all the weeds and yielded 35 bu, it was considered a success.

[Blacksandfarmer]

BA sounds like my area. We have much less organic matter in our soils than Iowa dirt, but you throw irrigation on that ground and we can raise 200+ bushel corn........ On ground, even with the cost of the pivot is still half the price of Iowa dirt. I don't believe we even have a CSR rating in Michigan.

[BA Deere]

Hi Blacksandfarmer, to have irrigation you can dial in the yields that you want, if your ground has a bit of sand you can change your soil`s chemistry more rapidly than a peat soil.  Just to show you what some of what I have here`s something off a soil test: 19% organic matter, I need 950lbs of potassium or I`m at a deficit, 130 lbs of nitrogen even though I didn`t apply any this fall, as a rule of thumb you can get 5lbs of N for each % of organic matter, it really holds phosphates I have about 3Xs more than I need at 900lbs.  The CSR is in the 40s, back when those soil types were rated the only weed control was a cultivator, only hand dug clay drainage tile, those soils were pasture in the 1940s, thus a CSR in the 40s. Illinois and Minnesota have similar ratings, Minnesota has a much more lax rating .  Land buyers use the rating as thee guide, paying +$100 for each CSR point, land for sale is calculated to the tenth.  CSR is a dollar value issue. 

[Blacksandfarmer]

Wow BA, the field with the highest organic matter on our farm tests out at 7%. The rest test out around 3%...... Needless to say we don't have the weed issues you have but fertilizer management is a priority here. P and K get spread in the fall on some farms but there is no such thing as fall nitrogen applications here.