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Soil Testing on Ranches

A soil test is the least expensive input on the ranch and one of the most useful. It replaces guesses with information, as long as the sample is taken well and the report is read with the right questions in mind.

Why test the soil

A soil test measures the nutrients available to plants and the acidity of the soil. It shows whether lime or fertilizer is likely to pay and which nutrients are lacking. Without it, producers often spend on the wrong thing or on nothing at all, and wonder why pastures stay thin.

Testing also gives you a baseline. Repeating the test every few years shows whether your management is building or draining fertility.

Many ranchers wait until a pasture looks poor before testing. It is better to test while the stand is still decent, since fixing a small problem costs less than rebuilding a failed pasture.

Dividing the ranch into sampling areas

Do not mix soil from very different places. Sample each pasture separately, and split a large pasture if it has different soils, slopes, history or plant types. Avoid odd spots such as old manure piles, fence lines, gates, wet spots and feeding sites, or sample them separately.

A simple pasture map with numbered sample areas makes results much easier to use later.

Write the sample area names on the bags the same way you write them on the map, so reports line up with fields when they come back.

• Sample by pasture or soil type
• Avoid manure piles and feeding areas
• Keep a map and notes on each area
• Record past lime and fertilizer use

How to take a good sample

Use a clean probe or spade and take many small cores from across the area, then mix them in a clean bucket. Send a subsample from that mix to the lab in the container provided. The more cores that go into the mix, the better it represents the field.

Ask your extension office the right depth for pasture and the best season to sample. Do not guess, because depth and timing change the result.

Sample at about the same time of year each cycle if possible. Moisture, recent fertilizer and temperature can all nudge results, and consistent timing makes comparisons cleaner.

Choosing a lab

University and commercial labs both do soil tests. Pick one that your extension service recommends, because the recommendations on the report are written for local soils and crops. Using the same lab each time makes results comparable over years.

Tell the lab what you are growing and how you will use it, such as grazing or hay, so recommendations fit.

Ask the lab how long results take and whether they will email the report. A short wait lets you plan lime or fertilizer ahead of the growing season rather than in a rush.

Reading the report

A typical report lists acidity, nutrient levels and recommendations. Some include organic matter and other measures. Ask your extension agent or a qualified advisor to explain what low, medium and high mean for your forage. Different labs use different scales, so do not compare numbers across labs without help.

Bring last year's report to the meeting if you have one. Comparing the two shows whether acidity or nutrient levels are moving in the direction you want.

Putting results to work

Use the report to rank problems. If acidity is the main limit, it makes sense to correct that before anything else. If a nutrient is low, the recommendation will suggest how to correct it for your forage. Follow label directions and local guidance when applying anything, and keep records of what you applied and when.

Consider the cost and the expected payback before spending. Talk to your lender or accountant if budget is tight. This is education, not financial advice.

Common mistakes and what to ask

Mistakes include sampling from one spot, mixing unlike areas, skipping the test for years and reading the numbers without help. Another is testing but never acting on the result.

Ask your extension agent how often to test, what depth to use, which lab to trust and how to read the report. Ask NRCS about conservation planning and any assistance.

Keep the reports together in one folder or file. Years of results are worth far more than any single sheet.

• One sample for a whole ranch
• Sampling feeding sites
• Not repeating the test
• Ignoring the recommendations

More in Nutrition, Forage & Grazing

• Lime and Fertilizer Decisions
• Weed Control in Pastures
• Brush Management on Ranches
• Poisonous Plant Control
• Pasture Renovation Basics
• Fencing for Rotational Grazing