# Help understanding soil sample



## SCtrailrider (May 1, 2016)

I got my soil sample back today and I would like some recommendations on what fertilizer mix to put down to get my low P&K up..

Field "D" will be getting lime as it is the field going to Fescue this fall..

They all are Fescue hay fields that will get reseeded if we get some rain..

Thanks, Chris


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## SCtrailrider (May 1, 2016)

This is the recommendations they sent, I just don't know what mix to tell them to mix... like 10-10-10 ???

The fella that runs the plant does give advice based on a sample but I would like to get other opinions also..

Chris


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## glasswrongsize (Sep 15, 2015)

Not knowing you soil type , I will use the recommended minimum for fertility that I have in my head for my soil

Here, the recommended minimum for P is 45; K is 250. I use a 4 year plan to get my soil to that minimum; using a 4 year plan to get yours to the minimum, you would need to add the following: (not inclusive of removed---12#P and 50#K per ton of hay are the numbers I use)

Your soil needs (in actual pounds of P and K in that order_

A 26p 190k

B 30p 154k

C 18p 173K

D 39p 199k

It takes 9 pounds of P to raise the soil sample by 1 pound and takes 4 pounds of K to raise by 1 pound. Divide that number by 4 years (the time plan) and you will find that you need (again in actual pounds per acre) the following for each of the next 4 years:

A 58.5 190

B 67.5 154

C 20.25 173

D 87.75 199

If using 18-46-0 or 0-46-0 for the P and 0-0-60 for the K, you would need the following pounds of fertilizer per acre each of the next 4 years

A 127 316

B 147 256

C 44 288

D 190 331

Here it is not recommended to put on over 300# of K per year, so the 316 and 331 would be 300 and take longer than 4 years to build to the minimum (again, not counting the removal of 12#/50# per ton)

Since you asked for the "10-10-10" equivalent, I figured the xx-xx-xx of each mixture (to the nearest whole number), but you shouldn't need it and it only muddles the situation. You would need the following pounds of the following ratios:

A 443 lbs of 5-13-42

B 403 lbs of 6-16-38

C 332 lbs of 2-6-52

D 521 lbs of 6-16-38

I would't pay any attention to the ratio ( I provided it because you mentioned it and it was a mental exercise for me) as it doesn't really mean anything unless you would rather tell the coffee shop crowd that you put on "443 lbs of 5-13-42 per acre" than to tell them you put on "127 lbs of DAP and 316 lbs of potash per acre". Both would be accurate.

73, Mark

PS, as always, check my math. Nothing looks like "that don't look right" to me, but I'm old and feeble-minded.

pps; I would speculate that the recommended numbers in the second post are for maint ( to compensate for removal), not to build fertility to a productive level


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## SCtrailrider (May 1, 2016)

Wow, sort of makes things more better for me to understand, very nice explanation, thank you...

I have a "red clay" based soil..

I mentioned the x-x-x because that is how he, ( plant op ) tells me what he would apply, and I guess that's the only way I somewhat understand it, but really don't.. but, I am attempting to learn a better way, like you explained it..

Thank you

Chris


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## rjmoses (Apr 4, 2010)

My thoughts:

Only one sample per field can be misleading. I usually get one sample every 2.5 to 5 acres. One sample can be substantially off causing you to over/under apply nutrients.

Overall, your soil tends to run neutral to sweet. No lime needed.

Nutrient (P and K) are way low (at least for soil types hereabouts. Generally speaking, I try to keep my Phosphorous (P) around 70 and Potassium (K) around 250-300.

Glasses recommendations are spot on for Illinois soils (they might be a little different in your area, but Clemson's recommendations should help) and I would suggest you study it carefully.

I have applied as much as 500 lbs of potash in one year by spreading it and then disking it in thoroughly about 6-8" deep. Surface-only application only migrates about 1/4" per year into the soil.

Hope this helps.

Ralph


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## r82230 (Mar 1, 2016)

Here is what a Spectrum Analytic soil sample results look like as a FYI (one of my old ones that I found here at the office). This is place that I think that Hugh mentions on another thread, that charges like $8 (plus postage). Note: the recommended amounts already include Mark's amount being removed (Ph & K amounts), that's why you have to tell them your goal/actual tonnage removal amounts. Your CEC has an influence on how well your soil holds nutrients is my understanding (I have sandy loam, doesn't hold as well as heavier soils).

Larry


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## vhaby (Dec 30, 2009)

glasswrongsize said:


> Not knowing you soil type , I will use the recommended minimum for fertility that I have in my head for my soil
> 
> Here, the recommended minimum for P is 45; K is 250. I use a 4 year plan to get my soil to that minimum; using a 4 year plan to get yours to the minimum, you would need to add the following: (not inclusive of removed---12#P and 50#K per ton of hay are the numbers I use)
> 
> ...


Glass,

The amount of P2O5 needed to raise the soil test P value by one pound varies according to soil pH. At a low pH, (strongly acid, like sample D) research data from Texas AgriLife Research indicate it takes as much as 29 pounds of P2O5 to increase soil test P by one part per million. As the pH is increased by liming to near 6.5, making soil P more efficient, the amount of P2O5 needed to increase soil test P by one part per million declines to about 12 pounds per acre.

Regards,

Vincent


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## glasswrongsize (Sep 15, 2015)

vhaby said:


> Glass,
> 
> The amount of P2O5 needed to raise the soil test P value by one pound varies according to soil pH. At a low pH, (strongly acid, like sample D) research data from Texas AgriLife Research indicate it takes as much as 29 pounds of P2O5 to increase soil test P by one part per million. As the pH is increased by liming to near 6.5, making soil P more efficient, the amount of P2O5 needed to increase soil test P by one part per million declines to about 12 pounds per acre.
> 
> ...


I'm sure Texas AgriLife Research is spot on for their soil. I'm equally sure that the University of Illinois is pretty close for ours. This is what they have to say about my soil and is the information upon which my guess was made

Buildup plus maintenance fertilization needed. When soil test levels are below the desired values (40, 45, and 50 for the high, medium, and low P-supplying regions, respectively), it is suggested that enough fertilizer be added to build the test to the desired goal and to replace what the crop will remove (as described in the previous paragraph). At this test level, the yield of the crop will be affected by the amount of P applied that year. For perennial forage crops, broadcast and incorporate all of the buildup and as much of the maintenance as economically feasible after primary tillage and before seeding. On soils with low fertility, reserve 30 pounds of P2O5 per acre for band seeding. Warm-season perennial grasses prefer fertile soils but grow well in moderate fertility conditions.
For establishment, fertilize with 24 to 30 pounds of P2O5. For these cropping systems, P rates beyond the year of establishment follow the regular maintenance or buildup plus maintenance program already described. *On average, Illinois soils require 9 pounds of P2O5 per acre to increase the P1 soil test by 1 pound.* *The recommended rate of buildup for P is thus nine times the difference between the soil test goal and the actual soil test value. For a typical 4-year buildup program, divide the rate by 4 to determine the annual rate. Because the 9-pound rate is an average for Illinois soils, some soils will fail to reach the desired goal in 4 years with P2O5 applied at this rate, and others will exceed the goal.*

*73, Mark*


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## SCtrailrider (May 1, 2016)

I am learning things I didn't know thanks to this thread...

I never knew or never had anyone explain it this way...

This is the first time anyone has said how much of anything to apply and how much it will change the ground... thanks very much...

Keep explaining it to this rookie, I like learning how to help my small patch of land....


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## r82230 (Mar 1, 2016)

SCtrailrider said:


> I am learning things I didn't know thanks to this thread...
> 
> I never knew or never had anyone explain it this way...
> 
> ...


Suggest that you continue to soil test the same field(s), roughly the same time (month perhaps), for several years in a row, while keeping track of not just what you applied (lime / fertilizer), but how much 'actual' tons of crop removed.

It you are small square baling, weigh several bales of each cutting. Put a load on your truck and run across a scale at your co-op or take a bathroom scale outside, weight yourself, then with a bale. If you are round baling, take a load to co-op (or local gravel pit) and weight (I have even haul two at a time to the co-op). The reason for weighing each cutting is there can be a lot of variables in making hay.

This year I have bought and started using a small set of scales from Gallagher, that has a load capacity of around 3,000 pounds. I use to weigh about 25-40% of my round bales at my local co-op, used the average of the load (weighed load if I had time to drive there and back). Thought I had a 'pretty' good handle on how much MY round bales weighed (averaged from load I hauled in). Well.................. with my new scales I able to weigh each bale individually...................I have had close to 200 pound variance in bale weight same cutting, same field, same day baled!!!!!!!!! :huh: Then had less than 25 pound variance. My finding, so far, new seeding not much grass, more consistent bale weights, older seeding's, variable grass/alfalfa, variable bale weights.

Note: I have been round baling for more than 25 years. I am presently using a BR7080, with auto tie (a moniter that tells you that you are light on one side or the other of the bale, that normally I can beat, by already feeding the light side before alarm goes off), so I don't consider myself a 'rookie' at round baling. I get comments (and asked how I do it) about my round bales having 'square' shoulders, which I answer - "it's not the color of baler, it's the operator". I could make square shouldered bales with an old NH850 chain baler (not at first, took awhile to learn).

Anyhow, I will now get even closer to MY actual tonnage removed, so I should be able to get closer to what I ACTUALLY need to put on for fertilizer, without 'wasting' any (excess fertilizer that is).

These soil tests and production records will give you valuable information about YOUR situation, using YOUR actual numbers, in YOUR area.

My two cents.

Larry


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