# Can I use an Old Soil Test years later



## gofastonit (May 27, 2021)

I had a soil test done 12 years ago and did not act upon it. My K was 47ppm and it was recommended that I apply 2.9 lbs/1000. Would this still be somewhat true after 12 years. I do mulch clippings and I have sandy soil. Any help would be appreciated.


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## Lawn Whisperer (Feb 15, 2021)

I think a 12 year old soil test is way too long.

Edit: I'm sure that a 12 year old soil test is too long. :mrgreen:


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## r7k (Jan 25, 2019)

someone correct me if i am wrong but doesn't grass (or crop) use up potassium at an equal or near equal rate as it does nitrogren? That being said if no significant lawn fertilization had been done then wouldn't it be expected that K would still be low? At least low enough to be fairly confident one application of anything, even 0-0-50 at a rate of 2 pounds to 1000 sqft is very unlikely to put K anywhere close to a high range?

Does K ever increase on its own with no help from humans in lawn turf, to where you would not want to fertilize?

my thinking you could use your 12 yr old report as some starting point... it may simply be you now need 2.x or 3.x of K applied per 1000 sqft. But if you were to get 0-0-50 sulfate of potash then if putting that down at a rate of 2 lbs per 1000 sqft (which is 1 lb of K per 1000 sqft) you're still well under any reasonable limit regarding K. You wouldn't put all 2.x or 3.x pounds of K down per 1000 sqft in one application anyway, the rate is supposedly 1 lb of K per 1000 sqft. After that how much and often you should worry about K specifically would be answered by a new soil test, which you would need anyway going forward.

After 12 years I wouldn't trust the pH value of that report. I don't know how likely / easy the other macro and micro elements are likely to change. If someone could comment on this that would be interesting.


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## gofastonit (May 27, 2021)

OK. I received my new soil test the other day. My potassium is lower than it was 12 years ago. It is now at 34.33.
I do have a 50# bag 0-0-60. My question now would be can I apply it in July in Michigan and if so at what rate.

12 Years ago the report said to use 3lbs of 0-0-60 per 1000sqft. I would imagine that rate should still be good.

Thanks in advance.


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## Virginiagal (Apr 24, 2017)

Did the soil test say you needed 3 lb of K or 3 lb of 0-0-60 per 1000 sq ft? Most likely, 3 lb of K, and it means 3 lb over the course of a year. For 0-0-60, you can apply 1.6 lb per 1000 sq ft of the product per application (once a month) to deliver 1 lb of K per 1000 sq ft. Mid to late August would be a better time to apply it (less stress on the grass). September would probably be ok too. Later fall applications of potassium have been associated with snow mold, so you may want to do other applications in the spring.


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## gofastonit (May 27, 2021)

My old report (From Michigan State Unerversity) said to apply 3 lb of 0-0-60 per 1000 sq ft. The new on just said the my K was low at 34ppm. The recomendatin from YardMastery was : Green Pop, MicroGreene and Started 12-12-12.


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## Virginiagal (Apr 24, 2017)

Yard Mastery gives a recommendation for only one application, which is not very useful. For 0-0-60, apply at 1.6 lb per 1000 sq ft per application.


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## gofastonit (May 27, 2021)

In your opinion is that OK to do now?


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## Virginiagal (Apr 24, 2017)

In my opinion it's better to wait until mid to late August as the grass is under plenty of stress right now with hot weather and there's no point in adding to it. It's not going to kill the grass if you do it now but why not wait. Water it in well whenever you apply it.


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## drcolossus11 (Jun 23, 2021)

Where in MI are you located? I'm in SE lower and it looks like we are in for another warm week in the mid to upper 80's. As @Virginiagal said, better to hold off until it's starts cooling off again. If you K is lower now than it was 12 years ago, what's another couple weeks?


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## Lawn Whisperer (Feb 15, 2021)

gofastonit said:


> My old report (From Michigan State Unerversity) said to apply 3 lb of 0-0-60 per 1000 sq ft. The new on just said the my K was low at 34ppm. The recomendatin from YardMastery was : Green Pop, MicroGreene and Started 12-12-12.


I wouldn't compare the results of the two soil test, the process to determine the values are different. The recommendation from the first soil test was 3 lb of 0-0-60 for the year.


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