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Soil sampling requirements in Texas

Soil sampling requirements in Texas

State guidance: Texas A and M AgriLife Extension, Procedure for Taking Soil Samples and TCEQ regulatory guidance for concentrated animal feeding operations.

Soil sampling in Texas: frequency, area, depth and cores

How often do you need to soil sample in Texas?

When in the year should soil be sampled in Texas?

How many acres can one soil sample cover in Texas?

How deep should soil samples be taken in Texas?

How many cores go into one soil sample in Texas?

How many soil samples does a 100-acre field need in Texas?

Texas A and M AgriLife Extension, Procedure for Taking Soil Samples: A uniform 100-acre field needs at least 3 composite samples of no more than 40 acres each, and at least 30 cores in all, 10 per sample.

Samples and cores for any field size

Soil sampling rules in Texas, with the exact wording of each source
Country / region Purpose / programme Time / frequency Area per sample Method Depth Cores Status and source
United States
TexasUnited StatesTexas only. Other states set their own rules.Routine soil fertility samplingTexas A and M AgriLife Extension, Procedure for Taking Soil Samples
  • Wait At least 2 months after the last fertilization
One composite sample for every 10 to 40 acres (4.05 to 16.19 ha)Separate samples for different soil types, land uses or fertilizer rates, cropping histories and terrain. Avoid fertilizer bands, small gullies, depressions, terraces, waterways and unusual areas.0 to 6 inches (0 to 15.24 cm)10 to 15 cores per composite (one core, then 9 to 14 more)Official guidanceTexas A and M AgriLife Extension, Soil Sample Information Form (PDF)
Who it applies to, the exact wording and every source
Who it applies to
Advice from the public land-grant university extension laboratory for Texas. Not law.
In force from
Under review
Legal text
Texas A and M AgriLife Extension Soil, Water and Forage Testing Laboratory, Soil Sample Information Form, Procedure for Taking Soil Samples

The wording in the source

Timing

  • When sampling fertilized fields, avoid sampling directly in fertilized band and wait at least 2 months after last fertilization.

    step 3

Area per sample

Method

Depth

  • Take a 0-6 inch sample, insure equal soil throughout this six inch depth.

    step 6

Cores

  • It is important to repeat steps 4-6 an additional 9 to 14 times for each area identified in steps 1-3.

    step 7

Sources

Sources re-checked every two months, last update October 2026. Reviewed by GeoPard editorial team.

TexasUnited StatesTexas only. Other states set their own rules.Soil monitoring on CAFO waste application fieldsTCEQ regulatory guidance for concentrated animal feeding operations
  • Season Before waste application begins, and after it begins
  • Repeat GPS grid method: sampled annually on the same grid layout
Not specifiedComposite per land management unit (LMU). Subsample locations by professional judgment, grid with random selection, or GPS grid.0 to 6 inches (0 to 15.24 cm) and 6 to 24 inches (15.24 to 60.96 cm). Where 0 to 2 and 2 to 6 inch samples (0 to 5.08 and 5.08 to 15.24 cm) are required, take the 0 to 6 inch sample and divide it.10 to 15 subsamples per depth per LMU, preferably 15Official guidanceTCEQ RG-408, Soil Sampling for CAFOs (PDF)
Who it applies to, the exact wording and every source
Who it applies to
State agency guidance for CAFOs that apply animal waste to land. Not law: the requirements sit in 30 TAC Chapter 321, Subchapter B and the CAFO general permit.
Laboratory and analysis
An agronomic soil laboratory, using the test methods in the Texas A and M AgriLife Soil, Water and Forage Testing Laboratory procedures.
Field identifiers
GPS each subsample location and keep it for two years (grid and GPS grid methods).
In force from
Under review
Legal text
TCEQ RG-408, Soil Sampling for Concentrated Animal-Feeding Operations (CAFOs), revised December 2017

The wording in the source

Timing

  • Before you begin to apply waste, and after you begin applying waste in accordance with the CAFO rules and General Permit, you are required to collect and analyze representative soil samples from each permitted land management unit (LMU)

    RG-408 p. 1, What is the purpose of soil sampling?

  • Sampling is conducted annually using the same grid layout to improve field sub-sampling consistency.

    RG-408 p. 3, GPS Grid Method

Method

  • Methods for locating subsamples include the following: professional judgment, grid and GPS Grid.

    RG-408 p. 2

Depth

  • If you are required to take 0–2 in and 2–6 in samples, collect a 0–6 in sample and divide according to depth.

    RG-408 p. 2

  • If you cannot collect the entire 6–24 in sample for more than the minimum 10 subsamples, specify the average depth that was obtained for the LMU.

    RG-408 p. 3

Cores

  • A representative composite sample typically should be composed of a composite of 10 to 15 (preferably 15) discrete subsamples for each depth increment within an LMU

    RG-408 p. 2

Laboratory and analysis

  • Coordinate with an agronomic soil laboratory

    RG-408 p. 1

  • appropriate soil test methodology found in the Standard Operating Procedures (SOPs) for the Texas AgriLife Extension Service Soil, Water and Forage Testing Laboratory.

    RG-408 p. 2

Field identifiers

Sources

Sources re-checked every two months, last update October 2026. Reviewed by GeoPard editorial team.

United States: federal rules and every other state

Soil sampling regulations in every country

Report an outdated requirement: info@geopard.tech

Plan the points to the rule that applies

Set the area per sample, the cores and the depth your rule asks for. GeoPard places the points on a grid or by zone, routes the walk, prints the labels and takes the plan to the field on a phone.

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