Soil testing for farm and ranch land
A soil map, a walk across the field and a lab test each answer different questions. Here is how they differ, how to prepare, and where to find a lab.
Find soil testing help
LSU AgCenter Soil Testing and Plant Analysis LaboratoryLouisiana
The LSU AgCenter lab in Baton Rouge that runs routine soil tests and plant tissue and irrigation water analysis. Its water test is for irrigation quality and does not determine whether water is safe to drink.
Tests listed by the lab: routine soil test, plant tissue analysis, irrigation water quality analysis, potting mix testing
Submitting samples: The lab's FAQ covers mailing and dropping off samples. It also suggests contacting a local extension office with questions.
Not sure which test you need? Your county office of LSU AgCenter can help you choose and read the results.
Well and water testing
EPA Private Drinking Water WellsNationwide
EPA guidance for private well owners, who are responsible for the safety of their own household water. Private wells are generally not regulated federally or by most states, so a buyer of a rural property with a well should read this and plan testing.
EPA: Certified Drinking Water Laboratories by StateNationwide
EPA page explaining that people who want their own drinking water tested should use a state-certified laboratory, and linking a document of each state's laboratory certification program. EPA says it cannot test residential water on request.
Test menus, sampling instructions and fees are set by each lab and change; we link to the lab's own pages rather than copying them. We do not state turnaround times, mail-in acceptance or accreditation unless the lab's own page says so.
Three kinds of soil information
- Mapped soil survey information. The NRCS Web Soil Survey shows mapped soil units, their typical properties and limitations. It is drawn at a scale where one map unit can include different soils, so it may not represent every part of a property, and a point lookup is not a summary of a whole farm.
- Field observations. Walking the land, digging test holes, and noting wet spots, slope, rock and erosion tell you about this site, but not its nutrient levels.
- A current laboratory test. A sample from your field, taken the way the lab instructs, is the only one of the three that measures current fertility. Mapped pH or old test results are not a fresh nutrient test for your field.
Different tests answer different questions
A routine fertility test (pH, phosphorus, potassium and similar) guides lime and fertilizer decisions. It does not certify that soil is free of contamination, that produce is safe, that a site will pass a septic or percolation test, or that it can support a foundation. Contamination and heavy-metal screening, irrigation and drinking-water testing, and geotechnical or percolation work are separate services, often from different providers and local offices.
Before you sample
- Decide what you plan to grow or graze, since labs and recommendations depend on the crop.
- Map distinct field areas (different soils, slopes, past use or management) and sample them separately.
- Follow the chosen lab's own sampling instructions: depth, number of cores and tools vary by lab and crop.
- Send the sample information and field history the lab asks for.
- Review the results with your county Extension office or a qualified crop adviser before buying inputs.
Farms and Ranches does not accept uploaded lab reports and does not produce fertilizer or pesticide recommendations.
Our full soil testing guide is in editorial and specialist review and will appear here once reviewed.