# Got soil test back. Confused about drastic changes from 2 years ago.



## waterboysh (Jun 6, 2019)

North FL with St. Augustine.

I did my first soil test in 2019. At the time, I thought my front and back yard might have drastically different results because the previous owner kept the front yard looking good and ignored the back. She had a big dog that ran around in the back and tore up the grass. When we moved in the back yard was 80% doveweed with lots of patches of soil visible. Turns out the results were fairly similar, so this year I sampled from all over the yard, mixed it all in one bucket, and sent in one soil sample.

The 2019 results showed very high P and very low K. So I have not added any P to the lawn at all. For the last 2 years, I've been adding 2lbs / 1000 of 0-0-50 every three months.

The 2020 results show that I'm low on P and even lower on K. I don't really understand. From what I've read, P stays in the soil a long time and the best way to remove it is to bag your clippings. I haven't been doing that; I've been mulching. So I don't know what results to believe.

Here are the actual test results. Also, here is the information in a Google Sheet. For 2019, I just averaged the front and back yard numbers.


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## desirous (Dec 15, 2017)

Did you use the same lab in 2019? Same sampling technique?


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## g-man (Jun 15, 2017)

There seems to be a lot of jumping in the numbers, more so in the pH. Can you describe your sampling methods in 2019 and now? depth, # of locations, etc.


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## waterboysh (Jun 6, 2019)

g-man said:


> There seems to be a lot of jumping in the numbers, more so in the pH. Can you describe your sampling methods in 2019 and now? depth, # of locations, etc.


Should be the same. I have a soil probe that I used. I made a line at 6" using a sharpie, pushed it into the soil down to the line, and then after I pulled it up I discard about the first two inches and then dumped the rest into a plastic bucket. I pulled way more samples than I needed; probably about 20 total from various areas in the front and back yard. Then I let the dirt air out for several days to dry. Then I sifted it.

The only thing I'm unsure of, is this year the soil sat for about a week in the bucket while we went camping, so it was close to 2 weeks between pulling the soil and the testing. I think when I did it in 2019, it would have been closer to one week. Not sure if that actually makes a big difference, but it's the only difference I can really think of between the sampling methods.


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## Ridgerunner (May 16, 2017)

Most likely the 2019 results are not accurate. pH can become lower naturally over time, but absent an addition of lime, they don't go up. P levels above 200 ppm is very high and very unusual. The 2021 test is more likely to be accurate, but before making any big changes I suggest you test again to break the tie.


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## ionicatoms (Mar 8, 2020)

@waterboysh
UF does the test locally and they are cheap.


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## waterboysh (Jun 6, 2019)

@ionicatoms I know. I used them once before. The test is only $7 but it's very basic, but might work as a quick reference for comparison. I applied Prodiamine 0-0-7 shortly after (Feb 20th) collecting the soil for the sample this year. I'll probably be putting down my first fertilizer application next weekend, so I'll probably pull some more soil samples just before doing that to submit to UF. I actually drive by the IFAS building every day to and from work so I can drop the sample off easily.


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## ionicatoms (Mar 8, 2020)

@waterboysh they combined the two separate tests ($7 Basic + $5 Micros) into a single package now for $10 which gives a more comprehensive view. You can see an example posted here.


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## waterboysh (Jun 6, 2019)

I got the soil test back from UF. I had applied 0-0-7 prodiamine about 6 weeks prior to collecting samples and X-Soil about 3 weeks (the weekend before I started this thread) before collecting samples. Since X-soil is classified as a soil amendment, it doesn't have to list what percent of N-P-K it might have. Just throwing this info out there because I'm not sure how it would affect the soil test.

Since the previous two tests both showed very low K levels, I think I can disregard the results for K from UF. It was likely affected by the 0-0-7. The P level is just a little bit lower than the first test I did in 2019 and the pH level is only different by 0.1 from that test as well.

I updated the Google Sheet that I linked in the OP to have the UF results in it. It's interesting; the results more closely track that of the 2019 test I had done with Spectrum Analytic. So I'm leaning towards the 2021 Spectrum Analytic test being the bad one. It's also interesting that SA says the optimal range for Magnesium is 150 - 300 and UF says my level of 150 is high. Going forward, I might just continue to use UF.

I want to try and get my P levels down some, so this year I'm planning on bagging and removing the clippings instead of mulching. I'll probably do something like mulch every 4th mow or something like that.


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