Geospatial Laboratory for Soil Informatics
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Service: Particle Size Analysis

Particle Size Analysis by Laser Diffractometry

The Geospatial Laboratory for Soil Informatics (GLSI) offers high-precision particle size distribution analysis using laser diffractometry. This method measures 101 bins of particle sizes from 0.01 – 2,000 µm, providing a detailed continuous curve result. The data can be aggregated into standard particle size fractions, included in our comprehensive report template.

Sample Preparation Requirements

Before submission, samples must be dried, ground, and sieved (2 mm max particle size). If you require assistance with grinding and sieving, we offer this as an additional service.

Our results spreadsheet automatically generates USDA soil texture classification and continuous curve graphs for each sample analyzed.
Pricing
Service (all costs are per sample) Internal External
Particle Size Analysis in deionized water $25.11 $30.13
Particle Size Analysis in alcohol $41.71 $50.06
Grinding, sieving, and homogenization $5.22 $6.26
Weighing of coarse fraction (>2 mm) $1.00 $1.20

Submitting Samples

When sending your samples, include the appropriate completed form:

FAQs

How much sample is needed for analysis? 

Laser diffraction requires only 1/8 teaspoon of fine-textured soil per run, while sandy samples may need 1/2 to 1 teaspoon. Each sample undergoes multiple quality control runs, so we ask for a minimum of 4 teaspoons (20 cm³) per sample. If measuring in grams, 40 grams is typically sufficient.

How can I ensure my sample is representative?

For the most accurate particle size results, submit the largest possible sample. If you must limit weight, we recommend:
✅ Homogenizing the sample thoroughly.
✅ Collecting from at least four different locations within the sample.

Can I ship samples for analysis?

Yes, but all samples must comply with USDA APHIS soil transport regulations.
🔗 Check USDA soil quarantine restrictions here

🚫 We cannot process international soil samples. Importing soil requires a USDA PPQ 330 permit, which our lab does not hold.

Where do I send my samples?

📍 Drop-off Location:
2312 Agronomy Hall, Iowa State University, Ames, IA

📦 Shipping Address:
GLSI, Department of Agronomy
Iowa State University
c/o Bradley Miller
2104P Agronomy Hall
716 Farm House Lane
Ames, IA 50011-1051

Where do I pay?

💳 Internal (ISU Clients): Provide a worktag at submission.
💰 External Clients: Iowa State University will generate an invoice and issue a payment number (credit cards are NOT accepted).
🔗 Payment details available here

Contact Us

📧 Questions or sample drop-off scheduling?
Contact Bradley Miller at millerba@iastate.edu

Particle Size Distribution Results

Below is an excerpt from our results spreadsheet, generated through our laser diffractometry procedure. The complete dataset includes measurements from 101 size bins, providing a high-resolution distribution of soil particle sizes.

These results can be:
📊 Visualized as a continuous graph of volume percent across all measured bins.
📂 Aggregated into standard size groupings for analysis as needed.

For detailed insights and customized reporting, please contact us for assistance in interpreting your data.

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