Ajay Kumar: Created a new article

2023-08-28T18:00:11Z

Created a new article

New page

{{Other uses|Geotechnical investigation}}
[[File:20150319-OC-LSC-0534 (16868799182).jpg|300px|thumb|A [[horticulture]] student taking a soil sample in a garden near [[Lawrenceville, Georgia]]]]
'''Soil test''' may refer to one or more of a wide variety of soil analysis conducted for one of several possible reasons. Possibly the most widely conducted soil tests are those done to estimate the plant-available concentrations of [[plant nutrition|plant nutrients]], in order to determine fertilizer recommendations in agriculture. Other soil tests may be done for engineering ([[geotechnical investigation|geotechnical]]), [[geochemical]] or [[ecological]] investigations.

== Plant nutrition ==
In [[agriculture]], a '''soil test''' commonly refers to the [[analysis]] of a [[soil]] sample to determine [[nutrient]] content, composition, and other characteristics such as the [[acidity]] or [[pH level]]. A soil test can determine [[fertility]], or the expected growth potential of the soil which indicates nutrient deficiencies, potential toxicities from excessive fertility and inhibitions from the presence of non-essential [[trace mineral]]s. The test is used to mimic the function of roots to assimilate minerals. The expected rate of growth is modeled by the [[Law of the Maximum]].<ref>{{cite book|url=https://books.google.com/books?id=iP7LWpn5oJ0C&q=%22law+of+maximum%22+wallace&pg=SL4-PA89 |title=Soil Science |date= 1999-08-31 |access-date=2012-11-08 |isbn=9780849331367 |last=Sumner |first=Malcolm E. }}</ref>

[[laboratory|Labs]], such as those at [[Iowa State]] and [[Colorado State University]], recommend that a soil test contains 10-20 sample points for every {{convert|40|acre|m2}} of field. [[Tap water]] or chemicals can change the composition of the soil, and may need to be tested separately. As soil nutrients vary with depth and soil components change with time, the depth and timing of a sample may also affect results.

Composite sampling can be performed by combining soil from several locations prior to analysis. This is a common procedure, but should be used judiciously to avoid skewing results. This procedure must be done so that government sampling requirements are met. A reference map should be created to record the location and quantity of field samples in order to properly interpret test results.

=== Geographic distribution of samples for precision agriculture ===
In [[precision agriculture]], soil samples may be geolocated using GPS technology in order to estimate the geospatial distribution of nutrients in the sampled area. The geolocated samples are collected using a distribution and resolution that allows for the estimation of the geospatial variability of the soil area where the crop will be grown. Many different distributions and resolutions are used, depending upon many factors including the goals of the geospatial nutrient analysis and cost of sample collection and analysis.<ref>{{Cite web|url=https://cropwatch.unl.edu/ssm/soilsampling|title=Soil Sampling for Precision Agriculture|date=2015-09-17|website=CropWatch|language=en|access-date=2019-05-22}}</ref><ref>{{Cite web|url=https://crops.extension.iastate.edu/using-precision-agriculture-improve-soil-fertility-management-and-farm-research|title=Using precision agriculture to improve soil fertility management and on-farm research {{!}} Integrated Crop Management|website=crops.extension.iastate.edu|access-date=2019-05-22}}</ref>

For example, in the United States corn and soybean growing regions a grid distribution with a resolution of 2.5 acres per grid (one sample for each 2.5 acre grid) is offered by many precision agriculture soil test service providers. This is generally referred to as grid soil testing.

=== Storage, handling, and moving ===
Soil chemistry changes over time, as biological and which chemical processes break down or combine compounds over time. These processes change once the soil is removed from its natural ecosystem (flora and fauna that penetrate the sampled area) and environment (temperature, moisture, and solar light/radiation cycles). As a result, the chemical composition analysis accuracy can be improved if the soil is analyzed soon after its extraction — usually within a relative time period of 24 hours. The chemical changes in the soil can be slowed during storage and transportation by freezing it. Air drying can also preserve the soil sample for many months.

===Soil testing===
Soil testing is often performed by commercial labs that offer a variety of tests, targeting groups of compounds and minerals. The advantages associated with local lab is that they are familiar with the chemistry of the soil in the area where the sample was taken. This enables technicians to recommend the tests that are most likely to reveal useful information.

[[File:Soil test.JPG|thumb|Soil testing in progress]]
Laboratory tests often check for plant nutrients in three categories:
* Major nutrients: [[nitrogen]] (N), [[phosphorus]] (P), and [[potassium]] (K)
* Secondary nutrients: [[sulfur]], [[calcium]], [[magnesium]]
* Minor nutrients: [[iron]], [[manganese]], [[copper]], [[zinc]], [[boron]], [[molybdenum]], [[chlorine]]

The amount of plant available soil [[phosphorus]] is most often measured with a chemical extraction method, and different countries have different standard methods. Just in Europe, more than 10 different soil P tests are currently in use and the results from these tests are not directly comparable with each other.<ref>{{Cite journal|last1=Jordan-Meille|first1=L.|last2=Rubæk|first2=G. H.|last3=Ehlert|first3=P. a. I.|last4=Genot|first4=V.|last5=Hofman|first5=G.|last6=Goulding|first6=K.|last7=Recknagel|first7=J.|last8=Provolo|first8=G.|last9=Barraclough|first9=P.|date=2012-12-01|title=An overview of fertilizer-P recommendations in Europe: soil testing, calibration and fertilizer recommendations|journal=Soil Use and Management|language=en|volume=28|issue=4|pages=419–435|doi=10.1111/j.1475-2743.2012.00453.x|s2cid=98596449 |issn=1475-2743}}</ref>

[[Do-it-yourself]] kits usually only test for the three "major nutrients", and for soil [[acidity]] or [[pH level]]. Do-it-yourself kits are often sold at farming cooperatives, university labs, private labs, and some hardware and gardening stores. [[Electrical meter]]s that measure pH, water content, and sometimes nutrient content of the soil are also available at many hardware stores. Laboratory tests are more accurate than tests with do-it-yourself kits and electrical meters. Here is an example [http://us.wlabs.com/wp-content/uploads/2013/02/samplesoilreport.pdf soil sample report] from one such laboratory, Wallace Laboratories LLC.

Soil testing is used to facilitate fertilizer composition and dosage selection for land employed in both agricultural and horticultural industries.

Prepaid mail-in kits for soil and ground water testing are available to facilitate the packaging and delivery of samples to a laboratory. Similarly, in 2004, laboratories began providing fertilizer recommendations along with the soil composition report.

Lab tests are more accurate and often utilize very precise [[Flow injection analysis|flow injection]] technology (or Near InfraRed (NIR) scanning<ref>[http://www.kake.com/story/40168844/on-the-spot-real-time-and-affordable-soil-testing-technology-is-enhancing-the-agricultural-value-chain-in-uganda On-the-spot, real-time and affordable soil testing technology is enhancing the agricultural value chain in Uganda.]</ref><ref>[http://ictupdate.cta.int/2019/01/14/on-the-spot-easy-and-affordable-soil-testing-for-kenyan-smallholder-farmers/ On-the-spot, easy and affordable soil testing for Kenyan smallholder farmers]</ref>). In addition, lab tests frequently include professional interpretation of results and recommendations. Always refer to all proviso statements included in a lab report as they may outline any anomalies, exceptions, and shortcomings in the sampling and/or analytical process/results.

Some laboratories analyze for all 13 mineral nutrients and a dozen non-essential, potentially toxic minerals utilizing the "universal soil extractant" ([[ammonium bicarbonate]] [[DTPA]]).<ref>{{cite web|url=http://us.wlabs.com/suitable-import-borrow-topsoil-or-reclaimed-soil/ |title=wlabs.com |publisher=Wallace Laboratories LLC |access-date=2012-11-08}}</ref>

== Engineering soil testing ==
{{div col|content=
* Water Content
* Specific Gravity
* Grain Size Analysis (Dry/Wet Sieve Analysis)
* Grain Size Analysis (Hydrometer Method)
* Liquid Limit
* Plastic Limit
* Shrinkage Factors
* Free Swell Index
* Swelling Pressure
* Dry Density, Light Compaction
* Dry Density, Heavy Compaction
* Moisture Content, Light Compaction
* Moisture Content, Heavy Compaction
* Heavy Compaction (Moisture Content)
* Unconfined Compressive Strength (UCS)
* Triaxial Compression test Cohesion C
* Direct Shear (Cohesion Intercept C)
* Relative Density
* Consolidation Test (initial [[void ratio]], e0)
* [[California bearing ratio]] (CBR)
* Falling head Permeability
* Constant Head Permeability
* Laboratory Vane Shear Test
* Direct Shear (Angle of shearing Resistance Phi)
* Triaxial Compression test (Angle of shear plane)
}}

==Soil contaminants==
Common mineral [[soil contaminant]]s include [[arsenic]], [[barium]], [[cadmium]], [[copper]], [[Mercury (element)|mercury]], [[lead]], and [[zinc]].

Lead is a particularly dangerous soil component. The following table from the [[University of Minnesota]] categorizes typical soil concentration levels and their associated health risks.<ref>{{cite web|author=Carl J. Rosen |url=http://www.extension.umn.edu/distribution/horticulture/DG2543.html |title=Lead in the Home Garden and Urban Soil Environment |publisher=Extension.umn.edu |access-date=2012-11-08}}</ref>

{| class="wikitable"
|+ Children and pregnant women should avoid contact with soil estimated total lead levels above 300 [[Parts per million|ppm]]
! Lead Level !! Extracted lead (ppm) !! Estimated total lead (ppm)
|-
| Low || <43 || <500
|-
| Medium || 43-126 || 500-1000
|-
| High || 126-480 || 1000-3000
|-
| Very high || >480 || >3000
|}

;Six gardening practices to reduce the lead risk

# Locate gardens away from old painted structures and heavily traveled roads
# Give planting preferences to fruiting crops (tomatoes, squash, peas, sunflowers, corn, etc.)
# Incorporate organic materials such as finished [[compost]], humus, and peat moss
# Lime soil as recommended by soil test (pH 6.5 minimizes lead availability)
# Discard old and outer leaves before eating leafy vegetables; peel root crops; wash all produce
# Keep dust to a minimum by maintaining a mulched and/or moist soil surface

==See also==

* [[Base-cation saturation ratio]]
* [[Fertilizer]]
* [[Geotechnical investigation]]
* [[Liming (soil)]]
* [[Plant tissue test]]
* [[SESL Australia]]

== References ==
{{Reflist}}

==External links==
* [http://www.epa.gov/ebtpages/pollsoilcontaminants.html Pollutants/Toxics > Soil Contaminants]
* [http://www.epa.gov/superfund/students/clas_act/haz-ed/ff_09.htm Common Contaminants]
* [http://www.ext.colostate.edu/pubs/Crops/00501.html Colorado State University Extension Service]
* [https://web.archive.org/web/20090627132930/http://grass-roots.ca/soil_test_info/why_a_soil_test.php Mail-in soil test kits and nutrient management/fertilizer reports]
* [https://purl.fdlp.gov/GPO/gpo41808 Field Book for Describing and Sampling Soils]
* [https://www.bpcipl.com/services/soil-testing-nabl-laboratory]

{{soil science topics}}
{{Geotechnical engineering}}
{{Authority control}}

[[Category:Soil tests| ]]
[[Category:In situ geotechnical investigations]]

Soil test - Revision history

Ajay Kumar: Created a new article