Soil test
Encyclopedia
In agriculture
, a soil test is the analysis of a soil
sample to determine nutrient and contaminant content, composition and other characteristics such as acidity or pH level. Tests are usually performed to measure the expected growth potential of a soil. A Soil test measures fertility
, indicates deficiencies that need to be remedied and determines potential toxicities from excessive fertility and inhibitions from the presence of non-essential trace minerals. 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.
Soil characteristics can vary significantly from one spot to another, even in a small garden or field. Taking samples everywhere in the field is crucial to get the most accurate measurement of nutrients and other organisms. An example of this is along gravel roads where the soil could have more lime from the dust from the roads settling down in the soil, or an old animal feedlot where phosphorus and nitrogen counts could be higher than the rest of the field.
Sample depth is also a factor for various nutrients, and other soil components vary during the year, so sample timing may also affect results. Usually the best time when soil tests can be done is spring.
Mixing soil from several locations to create an "average" (or "composite") sample is a common procedure but it must be used judiciously as it can artificially dilute quantities/concentration, and may not meet government agency requirements for sampling. Make a reference map for your filing system so you know where you took them, and how many samples you took in the field. All of these considerations affect the interpretation of test results.
Laboratory tests often check for plant nutrients in 3 categories:
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 meters 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 soil sample report from one laboratory.
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, though both types are useful. In addition, lab tests frequently include professional interpretation of results and recommendations. Always refer to all proviso statements included in a lab report - these may outline any anomalies, exceptions and shortcomings in the sampling and/or analytical process/results.
Lead is a particularly dangerous soil component. The following table from UMinn categorizes typical soil concentration levels and their associated health risks.
Six Gardening Practices to Reduce the Lead Risk
Some laboratories analyze for all 14 mineral nutrients and a dozen non-essential, potentially toxic minerals utilizing the “universal soil extractant” (ammonium bicarbonate DTPA) reference.
RECORD TEST: Record test means the tests of soil/murum taken for disturbed & undisturbed samples. Record tests are taken only in soil testing laboratory.
Following are the tests ( Record) taken for soil:
Following are the tests ( Record) taken for murum:
Shear test are taken on two machines.
Small shear machine- Small shear machine is used for hearting material & for casing material if particle size is less than 4.75mm.
Large shear machine – Large shear machine is used for casing material if particle size is more than 4.75mm.
Permeability test:- For Hearting material Permeability lies between 10-6 to 10-7
Permeability test:- For Casing material Permeability lies between 10-4 to 10-5
Agriculture
Agriculture is the cultivation of animals, plants, fungi and other life forms for food, fiber, and other products used to sustain life. Agriculture was the key implement in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that nurtured the...
, a soil test is the analysis of a soil
Soil
Soil is a natural body consisting of layers of mineral constituents of variable thicknesses, which differ from the parent materials in their morphological, physical, chemical, and mineralogical characteristics...
sample to determine nutrient and contaminant content, composition and other characteristics such as acidity or pH level. Tests are usually performed to measure the expected growth potential of a soil. A Soil test measures fertility
Fertility
Fertility is the natural capability of producing offsprings. As a measure, "fertility rate" is the number of children born per couple, person or population. Fertility differs from fecundity, which is defined as the potential for reproduction...
, indicates deficiencies that need to be remedied and determines potential toxicities from excessive fertility and inhibitions from the presence of non-essential trace minerals. 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.
Soil sampling
Labs, such as Iowa State and Colorado State University, recommend that you take between 10-20 samples for every 40 acres (161,874.4 m²) of the field. Tap water or chemicals could change the composition of the soil, and may need to be tested separately.Soil characteristics can vary significantly from one spot to another, even in a small garden or field. Taking samples everywhere in the field is crucial to get the most accurate measurement of nutrients and other organisms. An example of this is along gravel roads where the soil could have more lime from the dust from the roads settling down in the soil, or an old animal feedlot where phosphorus and nitrogen counts could be higher than the rest of the field.
Sample depth is also a factor for various nutrients, and other soil components vary during the year, so sample timing may also affect results. Usually the best time when soil tests can be done is spring.
Mixing soil from several locations to create an "average" (or "composite") sample is a common procedure but it must be used judiciously as it can artificially dilute quantities/concentration, and may not meet government agency requirements for sampling. Make a reference map for your filing system so you know where you took them, and how many samples you took in the field. All of these considerations affect the interpretation of test results.
Storage and handling
Soil chemistry changes over time as biological and chemical process 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 extraction--usually within 24 hours. The chemical changes in the soil can be slowed during storage and transportation by freezing it. Longer term soil sample preservation (many months) can be accomplished by air drying.Soil testing
Soil testing is often performed by commercial labs that offer a variety of tests targeting groups of compounds and minerals. There may be some advantage to using a local lab that is familiar with the chemistry of the soil in the area where the sample was taken. This enables technicians to recommend the tests most likely to reveal useful information.Laboratory tests often check for plant nutrients in 3 categories:
- Major nutrients: nitrogenNitrogenNitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...
(N), phosphorusPhosphorusPhosphorus is the chemical element that has the symbol P and atomic number 15. A multivalent nonmetal of the nitrogen group, phosphorus as a mineral is almost always present in its maximally oxidized state, as inorganic phosphate rocks...
(P), and potassiumPotassiumPotassium is the chemical element with the symbol K and atomic number 19. Elemental potassium is a soft silvery-white alkali metal that oxidizes rapidly in air and is very reactive with water, generating sufficient heat to ignite the hydrogen emitted in the reaction.Potassium and sodium are...
(K) - Secondary nutrients: secondary nutrients - sulphur, calciumCalciumCalcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft gray alkaline earth metal, and is the fifth-most-abundant element by mass in the Earth's crust...
, magnesiumMagnesiumMagnesium is a chemical element with the symbol Mg, atomic number 12, and common oxidation number +2. It is an alkaline earth metal and the eighth most abundant element in the Earth's crust and ninth in the known universe as a whole... - Minor nutrients: ironIronIron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...
, manganeseManganeseManganese is a chemical element, designated by the symbol Mn. It has the atomic number 25. It is found as a free element in nature , and in many minerals...
, copperCopperCopper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...
, zincZincZinc , or spelter , is a metallic chemical element; it has the symbol Zn and atomic number 30. It is the first element in group 12 of the periodic table. Zinc is, in some respects, chemically similar to magnesium, because its ion is of similar size and its only common oxidation state is +2...
, boronBoronBoron is the chemical element with atomic number 5 and the chemical symbol B. Boron is a metalloid. Because boron is not produced by stellar nucleosynthesis, it is a low-abundance element in both the solar system and the Earth's crust. However, boron is concentrated on Earth by the...
, molybdenumMolybdenumMolybdenum , is a Group 6 chemical element with the symbol Mo and atomic number 42. The name is from Neo-Latin Molybdaenum, from Ancient Greek , meaning lead, itself proposed as a loanword from Anatolian Luvian and Lydian languages, since its ores were confused with lead ores...
, aluminum.
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 meters 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 soil sample report from one laboratory.
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, though both types are useful. In addition, lab tests frequently include professional interpretation of results and recommendations. Always refer to all proviso statements included in a lab report - these may outline any anomalies, exceptions and shortcomings in the sampling and/or analytical process/results.
Lead is a particularly dangerous soil component. The following table from UMinn categorizes typical soil concentration levels and their associated health risks.
| Lead Level | Extracted Lead (ppm) | Estimated Total Lead (ppm) |
|---|---|---|
| Low | less than 43 | less than 500 |
| Medium | 43 to 126 | 500 to 1000 |
| High | 126 to 480 | 1000 to 3000 |
| Very High | greater than 480 | greater than 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.
Some laboratories analyze for all 14 mineral nutrients and a dozen non-essential, potentially toxic minerals utilizing the “universal soil extractant” (ammonium bicarbonate DTPA) reference.
RECORD TEST: Record test means the tests of soil/murum taken for disturbed & undisturbed samples. Record tests are taken only in soil testing laboratory.
Following are the tests ( Record) taken for soil:
- Grain Size Analysis.
- Moisture Content test.
- Specific gravity test
- Liquid limit test
- Plastic limit test
- Shrinkage limit test
- Compaction Test
- Direct Shear Test
- Permeability test.
Following are the tests ( Record) taken for murum:
- Grain Size Analysis.
- Moisture Content test.
- Specific gravity test
- Compaction Test
- Direct Shear Test
- Permeability test.
Shear test are taken on two machines.
Small shear machine- Small shear machine is used for hearting material & for casing material if particle size is less than 4.75mm.
Large shear machine – Large shear machine is used for casing material if particle size is more than 4.75mm.
Permeability test:- For Hearting material Permeability lies between 10-6 to 10-7
Permeability test:- For Casing material Permeability lies between 10-4 to 10-5
Soil Contaminants
Common mineral soil contaminants include:- ArsenicArsenicArsenic is a chemical element with the symbol As, atomic number 33 and relative atomic mass 74.92. Arsenic occurs in many minerals, usually in conjunction with sulfur and metals, and also as a pure elemental crystal. It was first documented by Albertus Magnus in 1250.Arsenic is a metalloid...
, BariumBariumBarium is a chemical element with the symbol Ba and atomic number 56. It is the fifth element in Group 2, a soft silvery metallic alkaline earth metal. Barium is never found in nature in its pure form due to its reactivity with air. Its oxide is historically known as baryta but it reacts with...
, CadmiumCadmiumCadmium is a chemical element with the symbol Cd and atomic number 48. This soft, bluish-white metal is chemically similar to the two other stable metals in group 12, zinc and mercury. Similar to zinc, it prefers oxidation state +2 in most of its compounds and similar to mercury it shows a low...
, CopperCopperCopper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...
, MercuryMercury (element)Mercury is a chemical element with the symbol Hg and atomic number 80. It is also known as quicksilver or hydrargyrum...
, LeadLeadLead is a main-group element in the carbon group with the symbol Pb and atomic number 82. Lead is a soft, malleable poor metal. It is also counted as one of the heavy metals. Metallic lead has a bluish-white color after being freshly cut, but it soon tarnishes to a dull grayish color when exposed...
, ZincZincZinc , or spelter , is a metallic chemical element; it has the symbol Zn and atomic number 30. It is the first element in group 12 of the periodic table. Zinc is, in some respects, chemically similar to magnesium, because its ion is of similar size and its only common oxidation state is +2...
.
See also
- FertilizerFertilizerFertilizer is any organic or inorganic material of natural or synthetic origin that is added to a soil to supply one or more plant nutrients essential to the growth of plants. A recent assessment found that about 40 to 60% of crop yields are attributable to commercial fertilizer use...
- Plant tissue testPlant tissue testThe nutrient content of a plant can be assessed by testing a sample of tissue from that plant. These tests are important in agriculture since fertilizer application can be fine-tuned if the plants nutrient status is known. Nitrogen most commonly limits plant growth and is the most managed...
- Geotechnical investigationGeotechnical investigationGeotechnical investigations are performed by geotechnical engineers or engineering geologists to obtain information on the physical properties of soil and rock around a site to design earthworks and foundations for proposed structures and for repair of distress to earthworks and structures caused...
- Liming (soil)
- ["One Hundred Harvests Research Branch Agriculture Canada 1886-1986". Historical series / Agriculture Canada - Série historique / Agriculture Canada. Government of Canada. http://epe.lac-bac.gc.ca/100/205/301/ic/cdc/agrican/pubweb/hs270060.asp.]
External links
- Soil Testing Soil Investigation
- Guide to testing the Electrical Conductivity of soil water
- California Landscape Ordinance Soil Management Report California Assembly Bill 1881 – effective January 1, 2010 California Landscape Ordinance For Water Conservation and Water-use Efficiency | www.bettersoils.com
- http://www.willingtoncropservices.co.uk/soil-sampling-conventional-w-pattern.htm Willington Crop Services shows techniques used for soil sampling UK farm fields in conventional W pattern.
- http://www.sandberglabs.com Soil Testing Resource in Canada and the USA as well as other agricultural testing.