very low soil pH help

enigma7(6)May 30, 2007

Hello everyone,

I have been converted to the (primarily) organic way primarily due to my almost year-old daughter and also for the health of the lawn. I did the CGM spring fert, along with a 40lb bag of greensand (my front yard is ~2000sq ft). I did not apply lime since I didn't know its affect on the microbes and also didn't think the soil was extremely bad.

I have a soil test kit that I've been waiting to send out until after all the ferts and additives have been completely broken down for fear of a false reading. But last week I decided to take a single core sample from the center of my lawn (about 3-6" in depth). I left it out overnight to dry, then dissolved it in DI water, filtered it, and then took the pH. I was SHOCKED to see it was ~4.7. My meter was properly calibrated.

I had recently put down a good amount of UCG's from the local starbucks but I was careful that my sampling was accurate and didn't have any grounds in it. I'm now wondering if my lawn really is that low. I will be taking another composite sample from a couple places around the yard, but if it looks similar I think a lime treatment is neccessary.

I'm going to wait another week or two for the purchased soil test sampling since I want to make sure its completely accurate (for the other nutrients), but I'm confident my pH testing is accurate.


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The coffee grounds wouldn't be responsible for a pH that low. Coffee is acidic, but the acid is water soluble, so the grounds are very close to neutral.

To get an accurate reading on pH, aren't you supposed to get samples from several places and mix them?

    Bookmark   May 30, 2007 at 11:32AM
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Yes, this was just a quick and dirty estimate of my lawn from a single point. Had it been 6.0 or even 5.5 I would have not worried much since that's borderline acceptable or only slightly needing a bump up in pH (figuring I just got an unlucky core). But to be below 5 was really shocking to me.

For those that don't know pH is a logarithmic scale. That means to go from pH 7.0 to pH 6.0 your soil is 10 TIMES as acidic at 6.0. Another jump to a pH of 5.0 means your soil is 100 TIMES as acidic as pH7.0. So for me to read at ~4.7 that means my soil is significantly more acidic than even the lowest recommended range (~5.5).

I've been having a good bit of chickweed and clover, and thought it was just a consequence of the organic program. Now I'm wondering if the underlying pH issue was the real culprit and not the switch to organic feed....

    Bookmark   May 30, 2007 at 12:40PM
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What harm does lime do to microbes?

    Bookmark   May 30, 2007 at 1:19PM
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A drastic pH change in any direction can stunt (slow metabolism) or outright kill certain microbes (I am no soil biologist/chemist however). In a lime treatment, I'm most concerned with the surface or very superficial soil level where a sudden (even if short-lived) increase in alkalinity of 1000-fold might have a negative effect.

    Bookmark   May 30, 2007 at 1:43PM
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rhizo_1 (North AL) zone 7

I'd run several pH tests to check for consistency.

    Bookmark   May 30, 2007 at 3:57PM
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The pH test was sound, the sample size was not (N=1). Yesterday I used my Hound-dog core aerator to pull up about 15 samples from my front yard. While these are only about 3" deep max, I have an even sampling from the yard to test with.

Same prep conditions as last time (broke the cores up and mixed the dirt, let it dry overnight outside). I'll hydrate in DI water, filter, and then test for pH. I'll report back here shortly. Thanks for everyone's help!

    Bookmark   May 31, 2007 at 7:02AM
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I sent my soil sample to Penn State. I too had very low Ph. Was recommened 50lbs lime/1000 sq ft. So I put down 500 lbs and ruined a perfectly good spreader in the process.

    Bookmark   May 31, 2007 at 9:47AM
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Whoops, I already posted this a couple hours ago but didn't know I needed to change the subject (it was rejected).

This time around my pH was 5.50. Much more reasonable (I actually guessed this prior to testing). I think I'll still treat with lime, but its much more comforting to know that I'm not horribly acidic.

I'm in SE PA (I'm guessing my soil type is a clay and/or loamy), and a quick google search came up with 1.66lb/yd of lawn to raise the pH from 5.5 to 6.5.

Can someone check my math that on a ~1800sq ft front yard I would need to add about 25lbs for that change? Seems much too low (I'm probably off by a zero), as I've put down 40lbs per 1000sq ft before without even thinking twice. I'm wondering if it was really 250lbs/1000sq ft?

Thanks everyone.

    Bookmark   May 31, 2007 at 11:09AM
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Hey enigma. I'm from south central PA(HBG area) Do you have any luck getting CGM in your area? I assume you're near Philly.

    Bookmark   May 31, 2007 at 2:09PM
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My mom found a GREAT feedstore where she lives (near Honeybrook). She was able to get me a 50lb bag of CGM for ~$26 if I remember correctly and also got 80lbs of greensand for ~$20 (an iron suppliment), and 50lbs of soybean meal for ~$15. I had called everyone around me (just outside the city) and no one had CGM or it was laughingly expensive (a buck a pound).

I'll have to call her up but I think it was called "A1 Feed" or something like that. Apparently its a huge agriculture store that is well known. I'll post back in here when I find out for sure.

    Bookmark   May 31, 2007 at 2:44PM
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smitty, you might want to check out triple m farms in Lebanon. (link below). Last time I checked they have CGM in 100 lb bags for like $20! I haven't gotten any yet but I talked to him last year. I'm sure it's not pelletized and I know it's not licensed. I'm not sure how easy the non-pelletized CGM is to apply with a spreader?

Here is a link that might be useful: triple m farms

    Bookmark   May 31, 2007 at 2:48PM
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Probably about as easy as applying non-pelletized nearly impossible. I tried that a while ago when I couldn't find pelletized at my local stores. It was slightly windy that day and it looked like I was shaking flour on the yard (and my neighbor's yard, and their neighbor's yard..) :)

Pickering Valley Feed is the place I was thinking about. It's off the turnpike and rt.113, so it should be easy to get to even if you're not local.

    Bookmark   June 1, 2007 at 6:46AM
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Yea, that's what I thought. I tried the non pelletized lime a couple weeks ago and boy, what a mess! I was covered in lime from head to toe. It took me longer to put the 2 bags of non- pelletized lime on than the 8 bags of pelletized. Live and learn.
Back to your original post...
Don't put 250lb/1000 sq ft, that's way too much. My Penn State results showed a ph of 5.7 and I was told to put down 90lbs/1000 sq ft. I'm going to put down less than half of that and re-test. I've also recently converted to organic and while doing research and reading through these forums, some people are saying that by switching to organic fertilizers, compost, etc., you'll raise your ph anyway.

    Bookmark   June 1, 2007 at 7:16AM
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Thanks enigma. CGM around here is about $1/lb at the local Agway. They do have SBM for $10.90/50 lb.

Gbig2. Lebanon is about 45 minutes from my place so that woud be local. That price sounds awfully cheap. If it's not licensed what does that mean?

As far as the lime I bought the pulverized instead of the pellet because it was $5 a bag cheaper but what pain in the a$$ just like you guys said. Also I ruined my spreader in the process.

    Bookmark   June 1, 2007 at 8:55AM
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Not licensed means that it's not being sold as a weed preventer, no licensing fees going to whatever university discover corn gluten. In order for companies to sell it as a weed preventer they need to pay someone a fee, so it's more expensive. Glenn from Triple m just returned my email, cutting and pasting from his email:
50 LB ALFAFA MEAL $13.25
100LB BAG OF 48% SOYBEAN MEAL $15.40
So great prices on CGM if you can figure out how to spread it, and great prices on SBM.
If only I had a lime spreader I'd be using that CGM exclusively as fertilizer/weed preventer on my lawn.
Wonder if you can rent them...

    Bookmark   June 1, 2007 at 11:19AM
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My original calculation said 25lbs/1000sq ft (the 250lbs was a joke!, I thought I might be off by a couple %). I found another site later in the day yesterday that had for clay soil 100lbs/sq ft to raise from 5.5 to 6.5 which is probably what Penn State was going by in their recommendation for you.

And yes, going organic will definitely help the pH. The nitrogen fertilizers such as Scott's are acidic in nature and will lower the pH of your soil (how much I don't know). Routine applications of these ferts along with normal erosion/acid rain, and its easy to see how we can have such low pH soil in our lawns.

Adding back in organic feed/compost/UCG will help cultivate the soil back into a moderate range (again how much and how quickly I have no idea).

I had originally thought to just know the pH of the soil but continue with my organic approach, but decided its best to bump it up a bit with the lime so everything is happier. Then my grass might be able to out-compete some of the weeds that have been more problematic in the last year or 2.

It's really funny. I moved into the house 4 1/2 years ago and at the time it was the BEST on the street. We are very good friends with the neighbors and they were always ticked that our house had the best lawn...why? Because they did virtually no upkeep. Never watered, never fertilized, cut very infrequently, all the while these other neighbors had lawn care services, watered religiously (light and frequent), fertilized with their chemicals, cut the grass nice and low :), and still suffered from weeds and poor lawns.

Unfortunately when I moved in (1st time home buyer) I got sucked into all the wrong things through bad advice (cutting too low, watering too frequently and much too little, using all sorts of chemicals (weed N' feed, Weed B' Gone, etc.).

And all this time I would have been better off with a method much closer to the "neglectful" previous owners. Now I cut high and frequently, water deep and infrequently, switched to organic ferts due to my daughter, and my grass (and right now the weeds!) look better than ever.

What a difference a site like this brings about.

    Bookmark   June 1, 2007 at 11:37AM
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If the CGM is not pelletized then what form does it come in? Having never seen it I'm not sure what it would look like. I know the SBM I use looks like finely ground soy beans and goes through the spreader quite easily. What is a lime spreader?

    Bookmark   June 1, 2007 at 2:01PM
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I'm assuming it would be finely ground up. Like pulverized lime but maybe not that fine. I've never gotten the non pelletized CGM so I'm not sure. Maybe one of the experts on this forum can tell us. Has anyone used non - pelletized CGM in a standard broadcast spreader?
I googled lime spreader and came up with links to those big machines that the farmers drag around to spread lime on their fields.

    Bookmark   June 1, 2007 at 3:16PM
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The CGM I put down never mentioned pelletized and looked like sand. It was dense enough that it wouldn't float away in a breeze (like pulverized lime will), but it was definitely very fine. I actually preferred this to a true pellet size since it dropped like a sheet of paper on my lawn and made it extremely easy to put down (and water in). I use a drop spreader and was able to line up my wheels perfectly since the CGM is bright yellow-orange in color.

I was sitting outside later in the evening when people would come by with their dogs and give me looks thinking I had overdone it with the pesticide/ferts. I just smiled back knowing I had the safest lawn on the block.

I was waiting for someone to make a rude comment...I would have walked over, grabbed a small pinch of it and threw it in my mouth. Then depending on the response either explained what it was or fake a seizure. :)

    Bookmark   June 4, 2007 at 12:17PM
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