Free Soil Testing Campaign

This soil testing campaign is funded through an On The Ground Conservation Program grant from the Texas State Soil and Water Conservation Board (TSSWCB).

In Fall 2025, TWRI proposed to the TSSWCB to reconnect landowners in the watershed with free soil testing to assist in minimizing non-point source nutrient pollution from runoff entering waterbodies and potentially reducing fertilizer costs for producers. TWRI was selected to receive funding in July 2026.

The 2026-2027 Soil Testing Campaign runs from September 2026 through March 2027. All agricultural producers in the Arroyo Colorado Watershed (Hidalgo, Cameron, and Willacy Counties) are eligible to participate in the free campaign. There is no acreage requirement nor limit to the amount of samples you can bring.

Your local AgriLife Extension center or the Harlingen TSSWCB office can provide you with sample bags, sample information forms, and instructions on proper soil sampling techniques. More information can be found on our flyer. Check out the Benefits of Soil Testing factsheet and more resources below!

You may also print the Soil Sample Information Form and attach it with your soil sample(s) that you drop off. Do NOT mail soil samples directly to the AgriLife Soil Lab. For this free campaign, they must be dropped off at the following locations:

Questions? Contact Samantha Colunga at samantha.colunga@ag.tamu.edu or (979)314-9382.

Other Resources

• Testing your Soil – https://arroyocolorado.org/wp-content/uploads/sites/50/2026/08/testing-your-soil-how-to-col-1.pdf
• Reduce Fertilizer Costs – https://farmassistance.tamu.edu/files/2026/03/2026-1.pdf
• Considerations of Soil Tests – https://agrilife.org/texasrowcrops/2018/11/06/eight-considerations-to-get-more-value-for-your-soil-test-dollars/
• Reduce Fertilizer Rates – https://agrilife.org/mid-coast-ipm/files/2017/09/Reducing-Nitrogen-app-by-Soil-testing-to-24-inches-Corn-1.pdf

Frequently Asked Questions

When should I do a soil test?

• Test 3-6 months before any new plantings or fertilizer applications
• Test once a year to track changes in soil health and nutrient availability.

How do I collect a soil sample?

• Take one composite soil sample for every 10 to 40 acres. This involves collecting 10-15 soil samples and mixing into one sample for a composite sample.
• Land with differences in past cropping, fertilization, soil types, or land use will require several composite samples.
• Sample from the top 6 inches of your soil. Make sure to remove plant material, plant litter, and roots from your soil sample.
• Place your composite soil sample(s) into your soil sample bag.
• More details on how to collect your soil samples can be found here or at the AgriLife Soil, Water and Forage Testing Laboratory

When and how will I receive my results?

• Please allow 2-3 weeks before receiving results
• Results will be emailed to the email you provide on the soil sample form.

Who can I contact to assist in interpreting my soil test results?

• Please contact Dr. Peter Omara – Assistant Professor & Extension Specialist, Soil and Crop Sciences (SCSC)
  • peter.omara@ag.tamu.edu
  • (956)968-5585

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