As I have written before, relying on ratios is dangerous because all
can be low or high, but with the correct ratios.
The optimum figures I have previously sent should be aimed for.
>At 5/15/2004 05:57 PM, ShortyB wrote:
>>Woody
>>
>>The grass staggers ratio is an example of numbers from a soil test. Look
>>at The Hill lab web site
>>http://www.hill-labs.co.nz/Files/PDFs/3193v4.pdf for
more info on
>>relationship between minerals for animal health.
>>The others are the difference between the minerals. Eg you should have 6
>>parts Ca to 1 part Mg.
>>Like many good labs Hills http://www.hill-labs.co.nz
>>have some useful info for the farmer.
>>Just remember guys these have all been developed for Nz farming systems.
>
>
>Hi Ian,
>
>Actually, the "Grass Staggers" ratio applies to the percentages of
>K, Ca, and Mg in the forage, not the soil. The coefficients correct
>the raw percentage values for milliequivalents, which is a way of
>dealing with differing atomic weights and valences. I downloaded the
>document and examined it. We use a similar formula here in the U.S.
>that gives nearly identical results.
>
>(Your formula originally listed "Mg/1215" but it should have listed "Mg/12.5")
>
>Also, I would caution that this Grass Staggers ratio is really a
>dependable predictor for forages with marginal magnesium values. If
>I run a "what if" exercise using a very low Mg value (0.10%) and
>reasonable K and Ca values, I can easily obtain a "safe" ratio of
>less than 2.0, even though from experience, we can confidently
>predict that a real forage with those values would be a very high
>risk. Conversely, I can obtain a "high risk" ratio of 2.5 with a
>very high Mg value of 0.28% and a high K of 3.5%. In reality, this
>forage would not be a high risk for magnesium tetany because of its
>very high Mg level.
>
>But for Mg levels of 0.13% through 0.20% or so, I would indeed look
>carefully at a Grass Staggers Ratio and consider it along with other
>factors.
>
>Best regards.
>
>Woody
>
><><><><><><><><><><><><><><><><
><><><><><><><><><><>
>Woody Lane, Ph.D. |
>Lane Livestock Services | voice: 541-440-1926
>240 Crystal Springs Lane | fax: 541-440-1007
>Roseburg, OR 97470 | email: wlane@rosenet.net
><><><><><><><><><><><><><><><><
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>
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--
Leon
