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Lawn soil test

by Johnny
(NE Alabama)

QUESTION:


I just got my soil test back. It shows low phosphorus level of 15.00 ppm (optimum 20 to 40 ppm) and a low potassium level of 37.00 ppm (optimum 150 to 250 ppm.) What is the best way to raise these levels?

ANSWER:

Johnny - To help us better answer your question, please provide the following information (just add a comment to your submission):

What type of grass are you growing? In NE Alabama you are most likely growing a warm-season grass - bermudagrass, zoysia or centipedegrass. Is your lawn established or are you planting a new lawn? What is your soil type - Sandy, clay, loam? What is the pH? Soil type and pH affect nutrient availability.

What you are referring to is the Nutrient Availability Index - and fertilizer rate recommendations for phosphorus and potassium are based on this index. Your soil test results should have a fertilizer recommendation - usually in pounds per acre - for phosphorus (P2O5) and potassium (K2O)- what are the recommendations?

Since your P and K levels are low, it will be helpful to use a complete (N-P-K) fertilizer based on your soil test results. Supply us with more information and we will help you develop your fertilizer program.

Organic matter acts as a storehouse for nutrients. Incorporating compost topdressing into your lawn maintenance program will also help you raise and maintain P and K levels.

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Apr 21, 2011
Lawn Soil Test - Additional Information
by: Johnny

The complete test was

pH -- 6.10
Soluble Salt -- 0.13
Phosphorus -- 15.00
Potassium -- 37.00

When I bought the house last year, it was mostly bermudagrass. They had the yard sod with bermuda in 2004, but I think it is to shady for bermuda. There is a lot of bare spots and a lot of moss. I would have to say the soil is clay with about 2 inchs of top soil.

I was thinking about just overseeding the entire yard.

Apr 22, 2011
Lawn Soil Test - Reply
by: Better-Lawn-Care.com

The pH is good and soluble salt not a problem. Bermudagrass will grow well in clay soils with 2 inches of topsoil. But you are right - too shady. Overseeding is a good option. What are you overseeding with? In Northern Alabama, you should be able to overseed with a perennial ryegrass/bluegrass/fine fescue blend. The ryegrass and fescues should fill in the shady spots. Fertilize with a complete fertilizer right after overseeding. Hopefully you have irrigation and consider overseeding with improved blends every fall.

To your original question, your lawn will respond to fertilizer additions of P and K right away. Use a complete fertilizer with a 4-1-2 ratio (For example 16-4-8). Apply your fertilizer to your bermudagrass lawn at a rate of 1 pound of nitrogen per 1000 ft2. Over time, you can raise the available P and K by topdressing with compost annually.

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