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Soil Test Interpretation and Advice

Posted by jayhoz Zone 5 (My Page) on
Wed, Jul 11, 12 at 11:41

Just received my soil test results for my KBG lawn in central MA. Some feedback on a plan would be much appreciated.

Front Yard
Soil pH: 6.2
Buffer pH: 6.6
Organic Matter: 7.5%
Phosphorus: 15ppm
Potassium: 108ppm
Calcium: 1067ppm
Magnesium: 293ppm
Cation Exchange Capacity: 12.4 Meg/100g
Percent Base Saturation: K=2.3 Mg=19.5 Ca=43.1
Extractable Aluminum: 49ppm
Boron: 0.1ppm
Manganese: 1.0ppm
Zinc: 0.0ppm
Copper: 0.4ppm
Iron: 5.7ppm
Sulfur: 22ppm
Recommendation: 50lb of calcitic limestone/1000 sq ft. 30-3-3 @ 3lbs/1000 sq ft in late April. 20-3-12 @ 5lbs/sq ft in late June and the very end of August. Year 2 30-3-3 @ 3lbs/1000 sq ft in April, June and the very end of August.

Back Yard
Soil pH: 5.5
Buffer pH: 6.1
Organic Matter: 7.6%
Phosphorus: 13ppm
Potassium: 79ppm
Calcium: 642ppm
Magnesium: 165ppm
Cation Exchange Capacity: 16.1 Meg/100g
Percent Base Saturation: K=1.3 Mg=8.45 Ca=20.0
Extractable Aluminum: 99ppm
Boron: 0.0ppm
Manganese: 1.1ppm
Zinc: 0.1ppm
Copper: 0.4ppm
Iron: 9.6ppm
Sulfur: 15.8ppm
Recommendation: 2 applications (Spring and Fall) of 50lb of calcitic limestone/1000 sq ft. 20-3-12 @ 5lbs/sq ft in April, June and the very end of August. Year 2 30-3-3 @ 3lbs/1000 sq ft in April, June and the very end of August.


Follow-Up Postings:

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RE: Soil Test Interpretation and Advice

I hope you didn't put down 50 lbs. of calcitic lime, that's way too much for one application. Seems like most soil testing labs get lime numbers wrong for turf, I think their recommendations are for crops, and no one bothered to change it in the computers they use. Anyway you still need calcitic lime. This looks like a Umass test, so that is what I will be using.

Front lawn: Not bad, although it looks like someone has been liming using dolomitic lime. pH is close to optimal, but I would do a high bag rate of calcitic lime (9-10 lbs. per 1000), or Cal Turf Pro (12 lbs per 1000) to raise it up a bit and to add calcium to your soil, which is on the low side. Too much magnesium in relation to calcium can tighten up soil, stunting root growth and water penetration, your ratio is not that great. Other than that, there's not much to do until late summer. Your P is a bit low, but nothing to worry about, and your K could use a little boost, but again, not a big deal. For your fall applications of fertilizer I would use starter this year (Sept., Oct.) which will help with P and K. Your micronutrients look like they need some help, but micros can be tough since too much can be toxic. I don't do micro recommendations because of this, but your boron, zinc and copper all look deficient. Iron you can raise with things like moss out, ironite, and Milorganite with no real worries about over application.

Back yard: Much worse back here. Your soil pH is about 1 pH point below where it should be. Calcitic lime at the high bag rate. You are also deficient in magnesium, so you need to add epsom salts. Buy some granular epsom salts at the drug store or supermarket and apply 2 lbs per 1000. Repeat in 90 days. You are a bit more deficient in K and P, so use starter in the fall as well. Your boron, zinc and copper are low too, and adding iron will help with lawn color.

On the bright side your organic matter percentages are very nice. You CEC shows a silty loam in the front, and a silty clay loam in back, which are good soils that hold nutrients and water well, so you should have no trouble having a nice lawn.


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RE: Soil Test Interpretation and Advice

Thanks for the great feedback. I understand the concerns about the application rate of the lime. What about the total lime needed recommendation? I assume one application at 9-10lbs/1000 isn't going to raise my pH by a full pH unit in the back yard. Should my plan be to hit it with lime every few months until I hit the 100 lbs/1000 recommended by UMass?

Also, this fall I plan to top dress and over seed about 1/3 of the front yard that is in particularly rough shape from the previous owner letting leaves sit on the lawn all winter. Should my plan be to lime first followed by the top dress and seeding a few weeks later?


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RE: Soil Test Interpretation and Advice

Pretty much, it's not an exact science, but it should be close to those amounts. I would test yearly in the spring for the front, the back you could probably hold off since the pH is much lower.

Well if you lime now, your next application should be in 90 days at the soonest, so that will put you in mid October, which should be fine if you seed around Sept. 1st.


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