Soil fundamentals library

[SD51555]

Given my failure to score some ag gypsum.....do you imagine calcitic lime to be of benefit for me? Much lower in magnesium than dolomitic lime, plenty of calcium, and I've got "room" to afford a bit of a pH boost. I believe this would be much easier to accomplish than gypsum procurement.
My CA:MG ratio really sucks.

Speaking of cation exchange, fwiw - by far the best performing portion of this ground (in terms of plant growth) was the portion headed "Jumbo S N", which also had the lowest cation exchange factor.

I think you could with your Jumbo N spot. You've got a 5.7 pH with a 6.5 buffer pH. Looks like you could put on 1.5 tons/ac of calcitic lime. A good calcitic lime is gonna be 30-35% or so calcium. I would look for a lime with a little (under 5%) magnesium in it. 3000 pounds would get you at least 900 lbs of calcium, or 450 ppm Ca rise. That would leave you right in the strike zone of good Ca to Mg balance. Your new Ca to Mg would be 1210 Ca to 127 Mg (assuming no Mg in the lime). If you can find a lime that is 2-4% magnesium and 28-32% calcium, you could go a little longer too. But I think 3000 pounds would put you in the low 6's for pH, and that's a pretty good spot to get good micros uptake and no pH drag.





If I could pick a pH, I like to aim for 6.3-6.5. That seems to be where it can all get in.

 

[SD51555]

Speaking of cation exchange, fwiw - by far the best performing portion of this ground (in terms of plant growth) was the portion headed "Jumbo S N", which also had the lowest cation exchange factor.

Randy Dowdy, the guy that won the national corn yield contest year after year grew his 600 bushel corn in soil that had a CEC of like 4 or 5. It was very sandy if I remember it right. Now keep in mind, this guy is spoon feeding foliar nutrients all season long through a pivot, but so could anyone else. I think with an extremely sandy soil and the ability to put on good water, he never wished for moisture, and he had more oxygen in his soil that anyone else.

I think pore space/oxygen is the yield limiting factor for all crops in heavy soil. In sandy non-irrigated soil, there is tons of oxygen and the yield limiting factor is moisture. This is also why I bang the drum so loudly for the sandy guys to focus on growing a solid duff layer to hold the temp down and keep it moist. I think those plots would deliver legendary yields if it could be kept from the sun. The moisture efficiency of a plot with a heavy duff layer is almost 100%. A little water lasts a long time that way.

 

[SD51555]

I went out and checked my sweet clover plot tonight. We’re finally starting to green up up here. I’ve got the duff layer, and we’re not getting the moisture to catch up after 5 years of drought.

Here’s my duff going into year 5 of our drought. I will say, after no snow this winter, I did get an inch three weeks ago, and another 7/10ths this week. That's enough to get me off to a good start, and probably carry me to far enough to get an early summer canopy, but I'll need another inch or two after August 15th to get a fall crop.

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[Buckhunter10]

Smashing down some major biomass
I’ll mow high anything that pops back up
I’ll then put my weed mat over this and leave it to breakdown and feed the soil and plants.

 

[Wind Gypsy]

One my plots has gotten so weedy that the clover doesn’t seem to hardly show up anymore to fight with the fleabane, oxeye daisy, goldenrod, and birdsfoot trefoil.

So I did the anti SD thing and nuked it with gly/2,4d and drilled in some enlist beans to have something living while the nukings continue.. feel as though I’ve betrayed my plan but hopeful it helps clean things up a bit. Maybe it’ll make it worse. I’ll learn something either way.

 

[SD51555]

One my plots has gotten so weedy that the clover doesn’t seem to hardly show up anymore to fight with the fleabane, oxeye daisy, goldenrod, and birdsfoot trefoil.

So I did the anti SD thing and nuked it with gly/2,4d and drilled in some enlist beans to have something living while the nukings continue.. feel as though I’ve betrayed my plan but hopeful it helps clean things up a bit. Maybe it’ll make it worse. I’ll learn something either way.

The answer is always calcium.

In this case, calcium would serve to antagonize your high Mg and K20.



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[Wind Gypsy]

The answer is always calcium.

In this case, calcium would serve to antagonize your high Mg and K20.

View attachment 77564

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Dump more calcitic lime on it? I might do that.. When i have time. Ph is low so it needs it anyway.

 

[SD51555]

Dump more calcitic lime on it? I might do that.. When i have time. Ph is low so it needs it anyway.

Verify with a quality soil test first. You needs pH and buffer pH reading.


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[Wind Gypsy]

Verify with a quality soil test first. You needs pH and buffer pH reading.


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It was tested last year, needs lime. 5.6 or 5.7 ph if I recall correctly. Which was the same or lower than prior tests that were taken before I spread over a ton/acre of dolomitic. I think some of that might be because i tested a little deeper sample last year than the prior one. Lime was surface spread and not incorporated with tillage. Plot has never been tilled by me.

It's just a PITA to put lime down.. Have (40) 50# bags from menards ready for pickup already. And after today, its going to be greasy out there!

 

[SD51555]

It was tested last year, needs lime. 5.6 or 5.7 ph if I recall correctly. Which was the same or lower than prior tests that were taken before I spread over a ton/acre of dolomitic. I think some of that might be because i tested a little deeper sample last year than the prior one. Lime was surface spread and not incorporated with tillage. Plot has never been tilled by me.

It's just a PITA to put lime down.. Have (40) 50# bags from menards ready for pickup already. And after today, its going to be greasy out there!

Do u know your buffer pH or cec?


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[Wind Gypsy]

Do u know your buffer pH or cec?

Oof. ph was worse than I thought. This was from '23, a year after the lime application. NE ALL is the plot with the bigger weed competition issues. Funny you mentioned Ca because its way lower than the other plot in that regard.

I'll have to pull samples again soon but I haven't done much since then other than annual gly burn down and drilling in fall seed blends.

 

[Buckhunter10]

Oof. ph was worse than I thought. This was from '23, a year after the lime application. NE ALL is the plot with the bigger weed competition issues. Funny you mentioned Ca because its way lower than the other plot in that regard.

I'll have to pull samples again soon but I haven't done much since then other than annual gly burn down and drilling in fall seed blends.

View attachment 77635

Would you describe these soils as variably different just by looking and feeling alone? Have the CECs moved from one test to the next?

I highly suggest
soil probe
mark 6inch depth
mark GPS coordinates on onx
take 3-4 plugs around each GPS coordinate
try to go same time of year, each year.
try to keep samples around a 1-3 acre grid for food plots.

In general - Lime and even gypsum for the CA and S would be massively beneficial, along highly diverse root systems.

Hope this helps!! Thanks for sharing the tests.

 

[Wind Gypsy]

Would you describe these soils as variably different just by looking and feeling alone?

Definitely.

Have the CECs moved from one test to the next?

Wasn't apples to apples. This is a test from the year prior - would compare to the SW plot rather than the NE one that has more weed issues. But, shows higher pH PRIOR to me putting over a ton/ac of ag lime on it. CEC was 16 vs 19. Results are from Ward labs. Odd that I'd have a 6.1 pH, put a ton+ of lime on it, and then have 5.6 the following year.

I highly suggest
soil probe
mark 6inch depth
mark GPS coordinates on onx
take 3-4 plugs around each GPS coordinate
try to go same time of year, each year.
try to keep samples around a 1-3 acre grid for food plots.

In general - Lime and even gypsum for the CA and S would be massively beneficial, along highly diverse root systems.

Hope this helps!! Thanks for sharing the tests.

Thanks! Oddly enough, with disappointing results from the '23 soil tests with low ph/nutrients and all, i had fantastic plot growth that year with a blend of oats, peas, beans, radish, MRC/fixation/alsike clovers, and chicory no-till drilled in August and rye broadcast in sept. That is why i didn't continue with more PITA lime applications. Last year i felt the plots were severely limited by water logged soils all fall which can be an issue in these locations. I planted a very similar blend both years. The SW plots are far from clean but have a strong rye/clover component returning to be the base of what I could terminate and drill into again in the fall. The NE is just dominated by weeds with some rye mixed in.

 

[Buckhunter10]

Definitely.

Wasn't apples to apples. This is a test from the year prior - would compare to the SW plot rather than the NE one that has more weed issues. But, shows higher pH PRIOR to me putting over a ton/ac of ag lime on it. CEC was 16 vs 19. Results are from Ward labs. Odd that I'd have a 6.1 pH, put a ton+ of lime on it, and then have 5.6 the following year.

View attachment 77638
View attachment 77639


Thanks! Oddly enough, with disappointing results from the '23 soil tests with low ph/nutrients and all, i had fantastic plot growth that year with a blend of oats, peas, beans, radish, MRC/fixation/alsike clovers, and chicory no-till drilled in August and rye broadcast in sept. That is why i didn't continue with more PITA lime applications. Last year i felt the plots were severely limited by water logged soils all fall which can be an issue in these locations. I planted a very similar blend both years. The SW plots are far from clean but have a strong rye/clover component returning to be the base of what I could terminate and drill into again in the fall. The NE is just dominated by weeds with some rye mixed in.

Interesting! The nice thing about lime, especially the CA aspect, even more so in CECs above 10, is that it can help with soil structure/flocculation. Think of layers of soil (on a microscopic level) as sheets of paper. If we want to stack sheets of paper on each other, we are stacking soil layers. Now, CA is a far larger molecule than MG, and H is even smaller. As you correct the PH and the saturations, the CA (and MG) will push H off between the sheets of paper (soil colloid). By doing so, it is like giving the distance between the sheets of paper a lift. Think of CA as a basketball and H as the tip of a ballpoint pen. If you have more basketballs between the sheets of paper, you will have a lot of air/water space. Similarly, if we have a lot of CA between the soil layers, we have lots more pore/water/airflow for our roots, water, and microbes.

This allows for better porosity, reduced compaction, etc. If you accompany this with a balanced pH, your chemical structure alone is very sound. That is when highly diverse mixes (already super risk-averse due to the inherent nature of diversity) can further shine!

So often, with water-logged soils, we need to keep an eye on the NA, as we don't want sodium to creep up and become an issue. Increase the CA to help porosity, and keep on rocking!!

 

[SD51555]

Oof. ph was worse than I thought. This was from '23, a year after the lime application. NE ALL is the plot with the bigger weed competition issues. Funny you mentioned Ca because its way lower than the other plot in that regard.

I'll have to pull samples again soon but I haven't done much since then other than annual gly burn down and drilling in fall seed blends.

View attachment 77635

For your SW MID plot:

Regardless of your sample variances, both show a big calcium problem, and you're feeling it in poor drainage. So you could take your pH up a half point from either soil sample and be ok. If your low test is accurate, 6.1pH is close enough. If your high test is acccurate, 6.6 is also close enough.

The lime rec chart is showing around 3-tons/ac for a lime addition to get a half point rise. A purely calcitic lime is gonna be 30-35% calcium. Let's say it's 30%, 6,000 pounds of lime is gonna give you 1800-2000 lbs calcium, or 900-1000 ppm increase in calcium. That'll take your Ca:Mg ratio from 4.7 : 1 (1644/348) up to 7.6 : 1 (1644 +1000 / 348).

Get there as fast as you want, but I'd cap it at no more than 3 tons calcitic lime total, and then an annual application of a few hundreds pounds of gypsum per acre. That'll continue to raise your calcium, and spoon feed sulfate sulfur to your crops and make them just a little sweeter than all the others.

 

[SD51555]

Oof. ph was worse than I thought. This was from '23, a year after the lime application. NE ALL is the plot with the bigger weed competition issues. Funny you mentioned Ca because its way lower than the other plot in that regard.

I'll have to pull samples again soon but I haven't done much since then other than annual gly burn down and drilling in fall seed blends.

View attachment 77635

On your NE ALL plot:

Much easier to move the needle here because you've got a higher buffer pH, even while having a lower starting soil pH. 4000 lbs calcitic will yield you around 1200 lbs/ac calcium, or 600 ppm. 600 ppm increase would bring your Ca:Mg ratio to 10.6. That's a tad frothy for calcium. Might not hurt to sub in a small amount of dolomitic lime if you have the ability. I'm not sure if you're dealing in bags or truckloads.

Could also just start with 3500 pounds/ac calcitic and just see how things grow for a year after.