How to Complete a Soil Test the Right Way
Introduction to soil testing
There are lots of reasons to want to test your soil. Perhaps you want to grow crops on your land and need to know; how fertile and rich in nutrients is your soil? Perhaps you want to be more precise and discover whether the soil is good for a particular crop, like wine grapes or fruit trees. Soil tests will reveal a lot of information about your soil that you want to know.
However, a soil testing service will also reveal some things you won’t want to know. It will reveal chemicals, toxins, heavy metals, in fact, any number of pollutants can and will be revealed. If you are a developer who wants to build an apartment complex you don’t want to build on land polluted with dioxins, pesticides or petroleum products. A soil testing lab will guide you through the discovery of all the benefits and all the dangers of soil samples from your land.
What will a soil test reveal
Hopefully your soil sample testing will reveal clean soil without pollutants and toxins. But the truth is that water, wind, previous landowners and a history of mismanagement have left most of our land polluted by some nasty things. Pesticides, herbicides, fertilizers and other chemical pollutants have been pumped into our land, water and air for over a century and have not just disintegrated and disappeared.
In fact when you look into a soil testing service laboratory they will offer you a list of potential pollutants they can look for in your soil that looks something like the one below.
Soil & Water: (Partial List)
How do I take a soil sample?
Soil samples are not difficult to collect but they will require some effort and care. Your soil testing lab will help guide you through the steps of soil sample collection with you. It is important that you collect samples from multiple locations on your land so that you will get to know the similarities and differences and because concentrations of substances may exist and should be located. Studies have shown that errors in sampling are 10 times more likely than errors in analysis. Therefore, when searching for a wide range of potential pollutants it is vital to use one of the following methods of sampling.
Multi-Incremental Sample preparation (MIS)
This method is used in the environmental field for taking samples of potentially contaminated soils for chemical analysis in a way that allows for accurate characterization of contamination in soils at a site. MIS provides representative samples through collection of numerous increments of soil that are combined, processed, and subsampled according to specific procedures in order to reduce the negative effects that soil heterogeneity has on environmental data.
Incremental Sampling Methodology (ISM)
Incremental Sampling Methodology (ISM) can help with this soil sample testing challenge. ISM is a structured composite sampling and processing protocol that reduces data variability and provides a reasonable estimate of a chemical’s mean concentration for the volume of soil being sampled. The three key components of ISM are systematic planning, field sample collection, and laboratory processing and analysis.
ISM replicate samples are established by collecting numerous increments of soil (typically 30 to 100 increments) that are combined, processed, and subsampled according to specific protocols. ISM is increasingly being used for sampling soils at hazardous waste sites and on suspected contaminated lands. Proponents have found that the coverage afforded by collecting many increments, together with disciplined processing and subsampling of the combined increments, yields consistent and reproducible results
What are the advantages of soil testing?
When a soil testing lab helps you collect your soil samples and analyzes them, they will look for specific mutually agreed upon contaminants. In their soil sample testing they will also identify some unspecified contaminants. And they will follow a set of well established procedures to ensure no contamination and high quality results. One of the greatest advantages with a soil testing lab is, you can be assured that they will produce highly accurate results. Additionally, they will give you a detailed report of the precise levels of every contaminant as well as analysis and explanation of their results for you. Your soil testing service will often also know where you should go for next steps.
How much does a soil test cost in your area
The costs of these tests vary widely depending on how many samples are collected, how many contaminants are sought out, whether further samples are needed for verification and other factors. But most labs have more information available upon request.
Multi-Incremental Sampling has several advantages:
- Less variability
- Higher reproducibility
- Greater confidence in decision-making
- Reduces likelihood of need to re-sample
- Provides option for volatile compositing
Torrent Laboratory has been performing MIS/ISM sample preparation since 2008 and has all the equipment necessary to prepare your samples. Torrent has a specifically written SOP for MIS/ISM, multiple grinding and sieving apparatus, storage racks that inhibit cross contamination between samples while still allowing for air drying, methodology adaptation to allow for increased sample mass, and QC Levels II, III, or IV available for reporting.