Soil PH Changes Over Time

Jerry

5 year old buck +
My PH tested at 7.8 early spring of 2021 without any amendments. I put 4 acres of ag beans in and left them for the deer - didn't combine them. I overseeded an acre in the middle of the beans with ladino clover and rye back in September. I plan to put either red clover or buckwheat on both sides of the clover this spring and use it as a cover crop. Then I plan to put one side in brassicas and one side in rye for the fall season. My question is how (if at all) does PH change over time with a rotation like this? I had good luck with the beans this season and might rotate them back in some year down the road but for now I plan the aforementioned rotation of green manure cover crops in the spring and brassicas/rye in the fall. I guess - in this scenario - what factors might decrease PH, if any?
 
Most plant root exudates acidify the plant root-soil interface, and by extension, the soil in general over time. However some plant species, especially small grains like cereal rye, may actually raise soil pH. I did a quick peer-reviewed literature search and couldn't immediately find anything on brassicas' effects on soil pH. Generally speaking, it would take years to decades of continuous cropping to see a measurable change in soil pH from nothing other than the crop species.

I'm curious if anyone else has any thoughts on this. Great question!
 
The cost of a good soil test isn't much and it will tell you all you need to know.
 
When I use to farm, the soil was pretty decent, (southern MN) I would only do a soil test every 5 years, and about half way through that I would add a maintenance amount of lime. But rarely would it need to be more then 1000# per acre. Over time you figure out next to pine, cedars, and oak trees you just spread a little thicker then you do the rest of the fields. But I think it has a lot more to do with how sandy your soil is, and how much CEC is in the soil to hold the minerals in the top layer.
 
If you don't add any inorganic fertilizers your PH isn't going to change a whole lot. If it were me I would just add gypsum every year. Your legumes will take care of your N input and will benefit from the calcium and sulfur. You may need to add some rock phosphate now and then and a light amount of micros once in a while. Like mentioned, soil test. You don't have to do it every year but every 3-4 years sure wouldn't hurt.

Going off of your last soil test results, do some research and find out the covers to spring plant that will "mine" the nutrients that are below the high classification. When you soil test every 3-4 years you can add any amendments needed and start the cycle over again.
 
I first applied ag-lime to raise my soil pH in the late 1990's. I opened up an additional 10 acres for food plots and applied ag-lime in 2014. At the time I only needed about 12-14 tons but had to buy an entire truckload (26 ton) so I spread the excess over my older plots even though it wasn't really needed. I have never noted any appreciable change in my pH levels over the years since the first application of ag-lime. It may vary slightly but I attribute that to just where I stick my soil probe when collecting samples.

The 6 soil samples I did last year came back as 6.9, 7.1, 7.1, 7.2, 7.2 and 7.5. I don't ever expect to have to apply any additional lime in my lifetime. I plant a wide variety of crops and rotate regularly.

I might add that this year will be my 7th year since going 100% no-till and cover cropping. My soil nutrient levels have risen to the point that I do not plan to apply any synthetic fertilizers at all this year.

Here is a sample result from last year:

IMG_7441.jpg

I will continue to monitor my soils periodically. I hope to see slight increases in CEC and OM (slowly, of course) as well as nutrient levels as a result of the no-till and cover cropping practices. Time will tell.
 
Jerry,

If your soil is naturally at 7.8, it should change very little over time with what you plant. In more naturally acidic soils where lime is required to get closer to neutral, it does leach out over the longer term due to rainfall, etc. requiring additional applications. You have a unique case where your soil appears to be naturally alkaline.

Synthetic fertilizers (especially those with higher Nitrogen components) will acidify soils. If you're wanting to bring down your soil pH some, you can always fertilize with AMS (21-0-0-24S) or any ammonium based nitrogen fertilizers. These are the most acidifying of all nitrogen fertilizer options (3 times as Urea for example, especially with the S component). AMS is a good option for brassicas as they also need the sulfur component for protein synthesis, and a boost to N utilization.

FWIW - Barley may be a good option for you (perhaps a good substitute for rye in your mixes), and can handle higher pH soils better. Its commonly grown in the upper midwest, Dakotas, etc where higher pH soils are the norm.

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Now, before we whack that beehive wide open, know that there are two distinct growing systems. One is a system of life that is never broken by chemicals or iron. The other is one that is regularly broken with chemicals or iron. Both have sets of knowledge that are true, but they are not interchangeable. In an unbroken system, very few additives are needed, and most will only do damage. In a broken system, significant additives are needed to keep plants alive and keep weeds at bay.

I operate in the unbroken bubble. I give little consideration to soil tests, only because they show a snapshot of what is available at that moment, but they can't show system capability to process and deliver bound up nutrients. For example, if I need 150lbs of potassium to make my desired crop, and I've got 150 days to grow it, and I'm only showing 1 pound of potassium, I'd say I have plenty for the whole season, because I know my system can free up 1 lb/day (better on warm and moist days) all season long. In a broken system, 1 lb/ac of potassium is a recipe for failure.

Here's a great watch from the guys at Green Cover. They interview a dude that's been studying biological (unbroken) systems for decades. I can't recall if it was 20 years or 30 years in this video, but they ran perennial polycultures in an unbroken system for decades and never applied a pound of potassium. Conventional wisdom would say we're mining out the nutrients. That is true in a broken system. That is not true in an unbroken system. After those decades, the soil tested for MORE potassium than when they started some decades earlier.

Start at 23:38 for the potassium part of the video. The dude's a tad hard to follow, but the slides are excellent.

 
^^^You got him going now.^^^
 
^^^You got him going now.^^^
I really believe, in the future, fertilizers, chemicals, and traited seeds will be gone. The info to eliminate all of them is already out there, it's just not well known or readily available. There are also lots of paychecks dependent on people not figuring out how to grow stuff with less inputs. Nobody is going to learn any of this in school buildings donated by Corteva or Bayer.
 
Now, before we whack that beehive wide open, know that there are two distinct growing systems. One is a system of life that is never broken by chemicals or iron. The other is one that is regularly broken with chemicals or iron. Both have sets of knowledge that are true, but they are not interchangeable. In an unbroken system, very few additives are needed, and most will only do damage. In a broken system, significant additives are needed to keep plants alive and keep weeds at bay.

I operate in the unbroken bubble. I give little consideration to soil tests, only because they show a snapshot of what is available at that moment, but they can't show system capability to process and deliver bound up nutrients. For example, if I need 150lbs of potassium to make my desired crop, and I've got 150 days to grow it, and I'm only showing 1 pound of potassium, I'd say I have plenty for the whole season, because I know my system can free up 1 lb/day (better on warm and moist days) all season long. In a broken system, 1 lb/ac of potassium is a recipe for failure.

Here's a great watch from the guys at Green Cover. They interview a dude that's been studying biological (unbroken) systems for decades. I can't recall if it was 20 years or 30 years in this video, but they ran perennial polycultures in an unbroken system for decades and never applied a pound of potassium. Conventional wisdom would say we're mining out the nutrients. That is true in a broken system. That is not true in an unbroken system. After those decades, the soil tested for MORE potassium than when they started some decades earlier.

Start at 23:38 for the potassium part of the video. The dude's a tad hard to follow, but the slides are excellent.


This is an outstanding video! Everyone should watch it. Thanks for posting it! Here are some things deer managers should consider:

The video is aimed at commercial farmers focusing a lot on expensive to grow crops like corn. Commercial farmers remove much of the above ground crop. They are applying way too much N. Now think about deer management where almost all of the residue is left to support soil microbiology as well as to contribute to nutrients as they decay. Much of what is consumed by deer is returned in droppings. Jus think how much less N we need to apply when we focus on soil health first using techniques like minimizing tillage and mixing/rotating complementary crops.

The talk on K shows how abundant it is and how flawed the testing is.

So, what does that mean for us deer managers when it comes to soil tests?
- Soil tests are great for pH management.
- Fertilizer recommendations are useless for me:
- Since they don't measure N and only consider the general needs of a monoculture crop, I've always ignored them.
- The video is pretty clear on K
- By using smart mixing of crops, we reduce the density of any one crop and thus the demands of any one nutrient on each cubic yard of soil.

Thanks,

Jack
 
Have not yet watched the video but will later when I have an hour or so to sit down and view it.

Thanks for the review Jack.
 
Now, before we whack that beehive wide open, know that there are two distinct growing systems. One is a system of life that is never broken by chemicals or iron. The other is one that is regularly broken with chemicals or iron. Both have sets of knowledge that are true, but they are not interchangeable. In an unbroken system, very few additives are needed, and most will only do damage. In a broken system, significant additives are needed to keep plants alive and keep weeds at bay.

I operate in the unbroken bubble. I give little consideration to soil tests, only because they show a snapshot of what is available at that moment, but they can't show system capability to process and deliver bound up nutrients. For example, if I need 150lbs of potassium to make my desired crop, and I've got 150 days to grow it, and I'm only showing 1 pound of potassium, I'd say I have plenty for the whole season, because I know my system can free up 1 lb/day (better on warm and moist days) all season long. In a broken system, 1 lb/ac of potassium is a recipe for failure.

Here's a great watch from the guys at Green Cover. They interview a dude that's been studying biological (unbroken) systems for decades. I can't recall if it was 20 years or 30 years in this video, but they ran perennial polycultures in an unbroken system for decades and never applied a pound of potassium. Conventional wisdom would say we're mining out the nutrients. That is true in a broken system. That is not true in an unbroken system. After those decades, the soil tested for MORE potassium than when they started some decades earlier.

Start at 23:38 for the potassium part of the video. The dude's a tad hard to follow, but the slides are excellent.

Very good video. Thanks for sharing, SD! I have a question. The guy said that K is put back into the soil by residue? Is N also put back into the soil by residue? If so, what crops put N, K, etc. back into the soil?
 
Very good video. Thanks for sharing, SD! I have a question. The guy said that K is put back into the soil by residue? Is N also put back into the soil by residue? If so, what crops put N, K, etc. back into the soil?
Both roots and residue release all the nutrients they hold into the soil as the microorganisms decay them. For adding N, you want to focus on including legumes in your mix. They, along with their symbionts, fix Nitrogen from the air into the soil.
 
Both roots and residue release all the nutrients they hold into the soil as the microorganisms decay them. For adding N, you want to focus on including legumes in your mix. They, along with their symbionts, fix Nitrogen from the air into the soil.
Diversity is key then!
 
Diversity is key then!
To a point, you are absolutely correct. This is not only true for soil health, but for deer as well. Many weeds contribute to diversity for free. For soil health, the mix/rotation of C and N (just like you are composting) is important. It is smart diversity. Mixes that include a grass (high carbon) and a legume (fixes N), help build OM which supports the soil microbiology. From a deer management standpoint, whether you are planting for attraction, or QDM, diversity is important. Again, smart diversity. For QDM, we need to have sufficient scale and we are planting to cover specific stress periods. The right mix of plants can cover those periods when nature is stingy. For attraction, different plants peak at different times. Mixing plants whose peaks are different can extend the attractiveness of a field.

Thanks,

Jack
 
Very good video. Thanks for sharing, SD! I have a question. The guy said that K is put back into the soil by residue? Is N also put back into the soil by residue? If so, what crops put N, K, etc. back into the soil?
Some K is cycled back from the residue, but some is also freed up from rock particles in the soil. Think of how above ground we see mosses and algaes grow on rock surfaces. The same thing happens below ground. Plant root exudates also will release rock bound nutrients. Every plant produces organic acids, and every one of those acids serves a purpose in either directly freeing rock bound nutrients, or supporting an organism that does it. Those acids can have very short half lives, some as short as a minute or two, so it's very important that there always be live plants on the soil.

Nearly all N accumulation happens below the soil. It's decomposing roots, decomposing organisms, nodulation on legume roots, microscopic grazers (a weed seed eaten by a beetle and turned into bug manure), an aphid eaten by a wasp, worm castings, worm slime, and nutrient transfer across mycorhizal networks. Focus on the plant mix, and the nitrogen will happen on it's own. It's been a while, but I believe I last read that an earthworm population at capacity will produce upwards of 3000 lbs/ac of stable plant available nitrogen in a growing season. Don't quote me on the number, but it's astronomical, to the point that nitrogen isn't the limiting factor in total output.
 
Some K is cycled back from the residue, but some is also freed up from rock particles in the soil. Think of how above ground we see mosses and algaes grow on rock surfaces. The same thing happens below ground. Plant root exudates also will release rock bound nutrients. Every plant produces organic acids, and every one of those acids serves a purpose in either directly freeing rock bound nutrients, or supporting an organism that does it. Those acids can have very short half lives, some as short as a minute or two, so it's very important that there always be live plants on the soil.

Nearly all N accumulation happens below the soil. It's decomposing roots, decomposing organisms, nodulation on legume roots, microscopic grazers (a weed seed eaten by a beetle and turned into bug manure), an aphid eaten by a wasp, worm castings, worm slime, and nutrient transfer across mycorhizal networks. Focus on the plant mix, and the nitrogen will happen on it's own. It's been a while, but I believe I last read that an earthworm population at capacity will produce upwards of 3000 lbs/ac of stable plant available nitrogen in a growing season. Don't quote me on the number, but it's astronomical, to the point that nitrogen isn't the limiting factor in total output.
That's crazy on the earthworm production! It makes you think why the farming industry went straight to conventional farming, tilling and using fertilizers when God put the ingredients right there in the soil to have a successful crop if done right! Greed comes to mind on the reason they went that route. :emoji_angry:
 
That's crazy on the earthworm production! It makes you think why the farming industry went straight to conventional farming, tilling and using fertilizers when God put the ingredients right there in the soil to have a successful crop if done right! Greed comes to mind on the reason they went that route. :emoji_angry:

The history of farming ( from Jethro Tull to inorganic fertilizers, etc) is an interesting read

Google up David Montgomery for a review

bill
 
That's crazy on the earthworm production! It makes you think why the farming industry went straight to conventional farming, tilling and using fertilizers when God put the ingredients right there in the soil to have a successful crop if done right! Greed comes to mind on the reason they went that route. :emoji_angry:

Ever watch old movies where over-population and starvation was the boogie man? It was a true fear back then. Folks never predicted how fast science advances would improve crop production. Greed is part of everything, as is fear, but farmers are truly amazing folks. I think back to when most farmers had nothing more than a high school education, if that. They learned what worked from their parents. Today many farmers have advanced degrees that include everything from financial to robotics. Farmers have made huge advances from 6-bottom plows to no-till drills. Folks like "Ray the soil guy" and other soil science folks have gone a long way with farmers evangelizing soil health.

Thanks,

Jack
 
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