How to Preserve Agricultural Evidence

Good Evidence Doesn't Happen by Accident

When crop damage, livestock losses, environmental contamination, or other agricultural incidents occur, one of the most common mistakes is waiting too long to document the evidence. By the time an investigator arrives days or weeks later, the crop has continued to grow, weather has changed the scene, machinery has entered the field, or valuable evidence has been lost forever.

Whether the issue involves herbicide drift, wildfire damage, livestock trespass, nutrient deficiencies, chemical contamination, construction damage, flooding, or mysterious crop failures, preserving evidence is the foundation of a successful investigation.

The quality of the evidence often determines the quality of the conclusions.

Why Evidence Preservation Matters

Agricultural evidence is constantly changing.

Plants continue to grow or die, insects move, diseases spread, rainfall washes away residues, and equipment can disturb important clues. Even memories become less reliable with time.

Proper documentation preserves the conditions as they existed when the damage was first discovered. It also helps ensure that decisions are based on objective evidence rather than assumptions.

Step 1 – Document Before You Touch Anything

Before collecting samples or moving anything, thoroughly document the scene.

Record:

• Date and time of discovery
• Legal land description
• GPS coordinates
• Weather conditions
• Wind direction and approximate wind speed
• Recent rainfall
• Crop growth stage
• A description of what was observed

Do not rely on memory. Write detailed notes immediately while the information is fresh.

Step 2 – Photograph Everything

Photographs often become one of the most valuable pieces of evidence.

Take photographs from several distances:

• Wide-angle photographs showing the entire field or affected area.
• Medium-distance photographs showing damage patterns, field boundaries, spray overlaps, wheel tracks, shelterbelts, drainage features, or other landmarks.
• Close-up photographs showing leaves, stems, flowers, roots, weeds, insects, disease symptoms, soil conditions, or damaged vegetation.

Always photograph healthy plants for comparison with damaged plants.

Whenever possible, enable GPS location services on your camera or smartphone so every image contains accurate location information. GPS-enabled photographs make it much easier to recreate the investigation months or even years later.

Take far more photographs than you think you will need. Digital photographs are inexpensive, while missed evidence can never be recreated.

Step 3 – Collect Samples Properly

Different investigations require different types of samples.

Examples include:

• Plant tissue
• Leaves
• Stems
• Roots
• Seed
• Grain
• Soil
• Water
• Fertilizer
• Crop residue
• Animal specimens
• Feed samples

Each sample should be collected using clean equipment to reduce the risk of cross-contamination.

Never mix samples from different locations.

Every sample should receive a unique identification number that matches your field notes, GPS location, photographs, and sample log.

Plastic Bags or Paper Bags?

Choosing the correct container is important.

Plastic bags are generally suitable for fresh plant tissue that will be kept cool and delivered to the laboratory promptly. However, moisture trapped inside plastic bags can encourage mould and tissue deterioration if samples are left warm for extended periods.

Paper bags allow moisture to escape and are often preferred for drying plant material, seed samples, or samples that may remain in storage before testing. They can also help reduce mould growth during transport.

When collecting any sample, follow the instructions provided by the laboratory that will perform the analysis. Different laboratories may have specific requirements depending on the type of testing being requested.

Should Samples Be Refrigerated or Frozen?

The answer depends on the sample and the laboratory analysis being requested.

Many fresh plant, water, or biological samples should be kept cool during transport to slow deterioration.

Some samples may require freezing to preserve their condition until analysis, while others should not be frozen because freezing can damage tissue or interfere with certain laboratory tests.

For this reason, samples should never be frozen simply as a precaution. Contact the receiving laboratory before collection whenever possible and follow its sample handling instructions.

Proper storage temperatures, containers, and shipping methods help ensure that laboratory results accurately reflect field conditions.

Step 4 – Maintain a Chain of Custody

If an investigation may involve insurance, arbitration, or legal proceedings, maintaining a documented chain of custody is essential.

The chain of custody records:

• Who collected each sample
• When it was collected
• Where it was collected
• How it was stored
• Who handled it
• When it was transferred
• Which laboratory received it

A complete chain of custody demonstrates that the evidence has been properly controlled from collection through laboratory analysis.

Step 5 – Record Accurate GPS Locations

Modern GPS technology greatly improves agricultural investigations.

Record GPS coordinates for:

• Sample locations
• Photograph locations
• Field boundaries
• Damaged areas
• Spray drift edges
• Dead trees
• Wetlands
• Watercourses
• Livestock entry points
• Utility crossings

Accurate GPS records allow investigators to revisit the exact locations later if additional sampling becomes necessary.

Step 6 – Use Drone and Aerial Imagery

Drone imagery has become one of the most valuable tools available to forensic agricultural investigations.

High-resolution aerial images can reveal:

• Spray drift patterns
• Wheel tracks
• Construction disturbances
• Livestock travel paths
• Drainage problems
• Variable crop injury
• Fire damage
• Flooding
• Soil erosion

Historical satellite imagery can also help determine when damage first appeared and whether similar issues existed in previous years.

Combining ground observations with aerial imagery provides a much more complete understanding of what occurred.

Step 7 – Use Accredited Third-Party Laboratories

Laboratory analysis should always be performed by qualified, independent laboratories using accepted scientific procedures.

Depending on the investigation, laboratories may analyze:

• Herbicide residues
• Soil nutrients
• Plant nutrients
• Plant diseases
• Water quality
• Heavy metals
• Hydrocarbons
• Feed quality
• Animal tissue
• Seed quality

Independent laboratory results provide objective scientific evidence that supports professional conclusions.

The Value of an Independent Forensic Agrologist

One of the greatest strengths of a forensic investigation is independence.

A forensic agrologist is not hired to advocate for one side or another. The role is to examine the available evidence objectively, collect and preserve information using accepted scientific methods, and develop conclusions that are supported by the facts.

An independent forensic agrologist can assist by:

• Documenting the scene before evidence changes.
• Collecting representative samples.
• Maintaining chain of custody.
• Coordinating laboratory analysis.
• Interpreting technical results.
• Preparing comprehensive investigation reports.
• Providing independent expert opinions for insurance, mediation, arbitration, or court proceedings.

Because the investigation is based on evidence rather than assumptions, independent findings often carry greater credibility with producers, insurance adjusters, lawyers, regulators, and the courts.

Final Thoughts

Agricultural evidence is often temporary. Every hour that passes can change the condition of crops, soils, water, animals, or the surrounding environment.

Good investigations begin with careful documentation, accurate photographs, properly collected samples, reliable GPS records, aerial imagery, and objective laboratory analysis.

Most importantly, preserve the evidence before attempting to explain the cause.

In forensic agrology, the evidence should always lead the investigation—not the other way around.