Editing Soil test (section)

===Lab testing===
[[File:Soil test.JPG|thumb|Soil testing in progress]]
Soil testing is often performed by commercial labs that offer a variety of tests, targeting groups of compounds and minerals. Laboratory tests often check for plant nutrients in three categories:
* Major nutrients: [[nitrogen]], [[phosphorus]], and [[potassium]]
* Secondary nutrients: [[sulfur]], [[calcium]], [[magnesium]]
* Minor nutrients: [[iron]], [[manganese]], [[copper]], [[zinc]], [[boron]], [[molybdenum]], [[chlorine]]

The amount of plant-available [[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 phosphorus tests are currently in use and the results from these different tests are not directly comparable.<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. An [http://us.wlabs.com/wp-content/uploads/2013/02/samplesoilreport.pdf example soil sample report] is provided for reference by Wallace Laboratories LLC.

In order to avoid complex and expensive analytical techniques, prediction based on regression equations relating to more easily measurable parameters can be provided by [[Pedotransfer function|pedotransfer functions]]. For instance, soil bulk density can be predicted using easily measured soil properties such as soil texture, pH and organic matter.<ref>{{Cite journal |last=Qiao |first=Jiangbo |last2=Zhu |first2=Yuanjun |last3=Jia |first3=Xiaoxu |last4=Huang |first4=Laiming |last5=Shao |first5=Ming’an |date=2019-01-01 |title=Development of pedotransfer functions for predicting the bulk density in the critical zone on the Loess Plateau, China |url=https://doi.org/10.1007/s11368-018-2040-1 |journal=Journal of Soils and Sediments |language=en |volume=19 |issue=1 |pages=366–372 |doi=10.1007/s11368-018-2040-1 |issn=1614-7480|url-access=subscription }}</ref> 

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. Provisory statements included in a lab report may outline any anomalies, exceptions, and shortcomings in the sampling, analytical process or 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>