Extension Search / Soil Labs / Louisiana
LSU AgCenter Soil Testing and Plant Analysis Lab
LSU AgCenter runs Louisiana’s public soil testing program. Send a soil sample and you get back your pH and nutrient levels, and what each number means for your plants.
Lab Details
LSU AgCenter
Baton Rouge, Louisiana
- Basic test
- Organic matter
- Micronutrients
Open the lab's site for fees, forms and the mailing address.
Test Methods
This lab uses:
- Phosphorus: Mehlich-3. Used across much of the East, South and Midwest, on acid to neutral soils.
- Potassium: Mehlich-3. Used across much of the East, South and Midwest, on acid to neutral soils.
- Micronutrients: Mehlich-3. Used across much of the East, South and Midwest, on acid to neutral soils.
Labs pull nutrients out of soil with different chemicals, and each one gives a different number for the same soil. 20 ppm on one test and 20 ppm on another don’t mean the same thing, so check which test your report used before you compare it to a chart.
Tests
- Basic test. pH, phosphorus and potassium, usually with calcium and magnesium. Enough for most gardens and lawns.
- Organic matter. How much organic matter the soil holds, which sets how much nitrogen it releases.
- Micronutrients. Zinc, iron, manganese and copper, sometimes boron.
- Kits are sold at parish Extension offices and many nurseries and hardware stores.
- Send ¾ to 1 pint of soil that hasn't just been fertilized or limed.
- Pay by check or money order. The lab doesn't take cash.
Sources: [1] [2] [3]
Out of State
The lab’s site doesn’t say whether it takes samples from other states. Ask before sending one.
Sample Tips
- Take 10 or more small cores across the area and mix them in a clean bucket. One spot tells you about one spot.
- Sample gardens and lawns about 6 inches deep, below any mulch or thatch.
- Keep beds that are grown differently, like a lawn and a vegetable garden, as separate samples.
- Wait a couple of months after fertilizing or liming, so the test reads the soil and not the last bag.
- Use the same lab and the same tests each time, so the numbers compare from year to year.
Your county Louisiana Extension office can help you take the sample and read the report.
Results
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