Minnesota Pollution Control Agency Logo

Minnesota Stormwater Manual

Difference between revisions of "Soil sampling and tests"

Line 89: Line 89:
 
Laboratory analysis of soil water content is recommended for point-in-time measurements. Lab methods involve weighing a soil sample prior to drying, then drying to constant weight in oven at temperature between 100–110<sup>o</sup>C (105<sup>o</sup>C is typical). The difference in weight represents the mass of water in the sample. The water content is then expressed on a mass basis (g of water to g of dry soil), or if the bulk density is known, the volume of water to volume of soil. It is important that samples collected in the field be properly stored to avoid water loss prior to analysis. For further reading see [https://nature.berkeley.edu/soilmicro/methods/Soil%20moisture%20content.pdf].
 
Laboratory analysis of soil water content is recommended for point-in-time measurements. Lab methods involve weighing a soil sample prior to drying, then drying to constant weight in oven at temperature between 100–110<sup>o</sup>C (105<sup>o</sup>C is typical). The difference in weight represents the mass of water in the sample. The water content is then expressed on a mass basis (g of water to g of dry soil), or if the bulk density is known, the volume of water to volume of soil. It is important that samples collected in the field be properly stored to avoid water loss prior to analysis. For further reading see [https://nature.berkeley.edu/soilmicro/methods/Soil%20moisture%20content.pdf].
  
−
For continuous measurements, field methods must be employed. Field methods are summarized below.  The most common methods are electrical resistance (e.g. time domain reflectometry), tensiometric, and radioactive (e.g. neutron probe). [https://www-pub.iaea.org/MTCD/Publications/PDF/TCS-30_web.pdf This document] provides a discussion of methods for measuring soil water content. [https://www.youtube.com/watch?v=jzYCuspFhwo This one hour video] provides an overview of soil water measurement.
+
For continuous measurements, field methods must be employed. Field methods are summarized below.  The most common methods are electrical resistance (e.g. time domain reflectometry), tensiometric, and radioactive (e.g. neutron probe). [https://www-pub.iaea.org/MTCD/Publications/PDF/TCS-30_web.pdf This document] and [https://pubs.usgs.gov/wsp/1619u/report.pdf this document] provide discussions of methods for measuring soil water content. [https://www.youtube.com/watch?v=jzYCuspFhwo This one hour video] provides an overview of soil water measurement.
 
*Electrical-resistance
 
*Electrical-resistance
 
**[https://www.youtube.com/watch?v=x_cegBUy1-I Video]
 
**[https://www.youtube.com/watch?v=x_cegBUy1-I Video]

Revision as of 12:21, 24 June 2021

This site is currently undergoing revision. For more information, open this link.
 Site is in development

There are hundreds of soil tests that can be conducted, both in the field or laboratory. This page provides an overview of more common soil tests, links to information on sampling, and links to test methods.

Information: Soil sampling should be conducted by trained and, where appropriate, certified professionals, such as licensed soil scientists and geoscientists
Information: Laboratory tests should be done by certified laboratories. The Minnesota Department of Health Environmental Laboratory Accreditation Program develops procedures and requirements to ensure accredited laboratories produce accurate and precise test results. Search for an accredited lab.

Sample collection

Soil sample collection methods vary and covering all acceptable methods is beyond the scope of this page. Below are links to sampling methods, including videos.

Sampling for chemical tests

Note that these references provide information on soil sample collection. Except where noted, they do not include field procedures associated with specific tests and most do not include information on quality assurance and quality control (QA/QC). Use professional, certified/licensed individuals or firms to ensure appropriate QA/QC procedures are followed.

Documents

Videos of sample collection for lab analysis

Laboratory tests

Below is a list of recommended laboratory tests.

Recommended holding times and preservation

Nutrients

Soil macronutrients include phosphorus, nitrogen, potassium, sulfur, calcium, and magnesium. Phosphorus is an important pollutant of concern in surface water, particularly lakes. Though there are several forms of phosphorus, they can roughly be divided into dissolved phosphorus and particulate phosphorus, with dissolved phosphorus being much more bioavailable than particulate forms. Dissolved phosphorus is typically identified as phosphorus passing through a 0.45 micron filter. For a detailed discussion of phosphorus, link here.

Nitrogen is also an important nutrient in both surface water and groundwater. Nitrogen concentrations in stormwater are typically below levels of concern for receiving waters.

Potassium, sulfur, calcium, and magnesium are typically not pollutants of concern in stormwater runoff, but they may be deficient in some soils and therefore potentially impact vegetation.

Metals

The primary sources of metals in stormwater runoff are associated with automobiles, both from fluids and wear of parts, including tires. Concentrations of metals in stormwater runoff are generally below aquatic life and drinking water criteria, though concentrations may exceed criteria for sensitive species and in specific land uses, such as high traffic transportation areas. Metals of potential concern include copper, zinc, nickel, cadmium, and lead.

Samples are typically collected for total metals, meaning samples are not filtered. For dissolved metal concentrations, samples are filtered using a 0.45 micron filter. From an environmental perspective, dissolved metal concentrations more accurately reflect potential risk to receptors, since most metal bound to particles is retained in stormwater bmps. Lab methods include the following.

pH

Soil pH typically ranges from 6 to 8. Soils with elevated organic matter concentrations may have lower pH. Soil pH affects biologic activity and chemical reactions, particularly of some metals. Soil pH is generally not a concern, though some amendments, such as lime (increases pH), may lead to soil pH values that adversely affect soil biology, vegetation, mobilize metals, or bind up nutrients. Recommended lab methods include the following.

Organic matter and carbon

Exchange capacity

Field methods

Soil water (moisture) content

Laboratory analysis of soil water content is recommended for point-in-time measurements. Lab methods involve weighing a soil sample prior to drying, then drying to constant weight in oven at temperature between 100–110oC (105oC is typical). The difference in weight represents the mass of water in the sample. The water content is then expressed on a mass basis (g of water to g of dry soil), or if the bulk density is known, the volume of water to volume of soil. It is important that samples collected in the field be properly stored to avoid water loss prior to analysis. For further reading see [4].

For continuous measurements, field methods must be employed. Field methods are summarized below. The most common methods are electrical resistance (e.g. time domain reflectometry), tensiometric, and radioactive (e.g. neutron probe). This document and this document provide discussions of methods for measuring soil water content. This one hour video provides an overview of soil water measurement.

Bulk density

Soil bulk density is an important measurement for determining soil infiltration and plant rooting properties. Measuring bulk density involves proper sample collection and laboratory analysis. Below are links to videos demonstrating methods for collecting bulk density samples.

Infiltration rate

Infiltration rates should be measured in the field. This page provides information on measuring soil infiltration rates.

Retrieved from "https://stormwater.pca.state.mn.us/index.php?title=Soil_sampling_and_tests&oldid=53300"

Privacy policy