Editing Soil (section)

== Physical properties ==
{{main|Physical properties of soil}}
{{for|the academic discipline|Soil physics}}

The physical properties of soils, in order of decreasing importance for ecosystem services such as [[crop production]], are [[Soil texture|texture]], [[Soil structure|structure]], [[bulk density]], [[Pore space in soil|porosity]], consistency, [[temperature]], [[Soil color|colour]] and [[resistivity]].<ref>{{cite book |last1=Gardner |first1=Catriona M.K. |last2=Laryea |first2=Kofi Buna |last3=Unger |first3=Paul W. |date=1999 |title=Soil physical constraints to plant growth and crop production |edition=first |location=Rome, Italy |publisher=[[Food and Agriculture Organization of the United Nations]] |url=https://citeseerx.ist.psu.edu/document?repid=rep1&type=pdf&doi=8dc3f09583443adcb37d380bde37398f479386ba |archive-url=https://web.archive.org/web/20170808175354/http://www.plantstress.com/Files/Soil_Physical_Constraints.pdf |archive-date=8 August 2017 |url-status=live |access-date=26 January 2025 }}</ref> Soil texture is determined by the relative proportion of the three kinds of soil mineral particles, called soil separates: [[sand]], [[silt]], and [[clay]]. At the next larger scale, soil structures called [[ped]]s or more commonly ''soil aggregates'' are created from the soil separates when [[iron oxide]]s, [[carbonate]]s, clay, [[silica]] and [[humus]], coat particles and cause them to adhere into larger, relatively [[Soil aggregate stability|stable]] secondary structures.<ref>{{cite journal |last1=Six |first1=Johan |last2=Paustian |first2=Keith |last3=Elliott |first3=Edward T. |last4=Combrink |first4=Clay |journal=[[Soil Science Society of America Journal]] |volume=64 |issue=2 |title=Soil structure and organic matter. I. Distribution of aggregate-size classes and aggregate-associated carbon |url=https://www.researchgate.net/publication/280798601 |year=2000 |pages=681–689 |doi=10.2136/sssaj2000.642681x |access-date=26 January 2025 |bibcode=2000SSASJ..64..681S}}</ref> Soil [[bulk density]], when determined at standardized moisture conditions, is an estimate of [[Soil compaction (agriculture)|soil compaction]].<ref>{{cite journal |last1=Håkansson |first1=Inge |last2=Lipiec |first2=Jerzy |journal=Soil and Tillage Research |volume=53 |issue=2 |title=A review of the usefulness of relative bulk density values in studies of soil structure and compaction |url=https://www.researchgate.net/publication/222541793 |year=2000 |pages=71–85 |doi=10.1016/S0167-1987(99)00095-1 |bibcode=2000STilR..53...71H |s2cid=30045538 |access-date=26 January 2025 |archive-date=16 May 2022 |archive-url=https://web.archive.org/web/20220516120555/http://directory.umm.ac.id/Data%20Elmu/jurnal/S/Soil%20%26%20Tillage%20Research/Vol53.Issue2.Jan2000/1452.pdf |url-status=live }}</ref> Soil porosity consists of the void part of the soil volume and is occupied by gases or water. Soil consistency is the ability of soil materials to stick together. Soil temperature and colour are self-defining. Resistivity refers to the resistance to conduction of [[electric current]]s and affects the rate of [[corrosion]] of [[metal]] and [[concrete]] structures which are buried in soil.<ref>{{cite journal |last=Schwerdtfeger |first=William J. |journal=[[Journal of Research of the National Bureau of Standards]] |volume=69C |issue=1 |title=Soil resistivity as related to underground corrosion and cathodic protection |year=1965 |pages=71–77 |doi=10.6028/jres.069c.012 |url=https://nvlpubs.nist.gov/nistpubs/jres/69C/jresv69Cn1p71_A1b.pdf |access-date=26 January 2025 }}</ref> These properties vary through the depth of a soil profile, i.e. through [[soil horizon]]s. Most of these properties determine the [[Permeability of soils|aeration]] of the soil and the ability of water to [[Infiltration (hydrology)|infiltrate]] and to be [[Soil water (retention)|held]] within the soil.<ref>{{cite book |last=Tamboli |first=Prabhakar Mahadeo |date=1961 |title=The influence of bulk density and aggregate size on soil moisture retention |location=Ames, Iowa |publisher=[[Iowa State University]] |url=https://dr.lib.iastate.edu/server/api/core/bitstreams/85621186-4b03-4140-ad1c-b18c3ab3b4a8/content |access-date=26 January 2025 }}</ref>