{"id":735,"date":"2025-11-04T08:29:50","date_gmt":"2025-11-04T16:29:50","guid":{"rendered":"https:\/\/extension.wsu.edu\/pnw-gardeners-handbook\/?page_id=735"},"modified":"2026-04-02T13:34:15","modified_gmt":"2026-04-02T20:34:15","slug":"chapter-5-urban-soil-management","status":"publish","type":"page","link":"https:\/\/extension.wsu.edu\/pnw-gardeners-handbook\/chapter-5-urban-soil-management\/","title":{"rendered":"Chapter 5: Urban Soil Management"},"content":{"rendered":"<div class=\"wsu-hero wsu-width--full wsu-pattern--wsu-light-radial-left  wsu-hero--style-boxed \">\n\t<div class=\"wsu-hero__background\">\n\t\t<div class=\"wsu-image-frame wsu-image-frame--fill\">\n\t<img decoding=\"async\" src=\"https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/11\/Chapter5-lead.jpg\"\n\t\tsrcset=\"https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/11\/Chapter5-lead.jpg 1350w, https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/11\/Chapter5-lead.jpg 300w, https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/11\/Chapter5-lead.jpg 1024w, https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/11\/Chapter5-lead.jpg 768w\"\n\t\tsizes=\"(max-width: 1350px) 100vw, 1350px\"\n\t\talt=\"Three people are digging a hole in the ground with shovels in a garden area covered in mulch.\"\n\t\tstyle=\"object-position: 46% 41%\"\n\t\t\/>\n<\/div>\n\t<\/div>\n\t<div class=\"wsu-hero__overlay\">\n\t<\/div>\n\t<div class=\"wsu-hero__content-wrapper\">\n\t\t<div class=\"wsu-hero__inner-content-wrapper\">\n\t\t\t\t\t\t<div class=\"wsu-hero__title-wrapper\">\n\t\t\t\t<h1 class=\"wsu-hero__title\">Urban Soil Management<\/h1>\t\t\t\t<div class=\"wsu-hero__caption\">Chapter 5<\/div>\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t<div class=\"wsu-hero__content\">\n\t\t\t<\/div>\n\t\t<\/div>\n\t<\/div>\n<\/div>\n\n\n\n<p class=\"wsu-max-width--hero wsu-spacing-after--xsmall\"><strong>Richard T. Koenig<\/strong>, Professor of Soil Science, Department of Crop and Soil Sciences, Washington State University<\/p>\n\n\n\n<p class=\"wsu-max-width--hero wsu-spacing-after--xsmall\"><strong>Paul R. Grossl<\/strong>, Department of Plants, Soils and Climate, Utah State University, Logan<\/p>\n\n\n\n<div style=\"height:10px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\" \/>\n\n\n<div class=\"wsu-row wsu-row--sidebar-right\" >\r\n    \n<div class=\"wsu-column\"  style=\"\">\r\n\t\n\n<h2 class=\"wp-block-heading wsu-font-size--xlarge wsu-heading--style-marked wsu-spacing-after--xxmedium\" id=\"learning-objectives\">Learning Objectives<\/h2>\n\n\n\n<ul>\n<li>Understand the physical, chemical, and biological disturbances and processes unique to urban environments and how they impact plant growth, development, and health.<\/li>\n<\/ul>\n\n<\/div>\r\n\n\n<div class=\"wsu-column\"  style=\"\">\r\n\t\n\n<h2 class=\"wp-block-heading\">Topics Covered<\/h2>\n\n\n\n<ul class=\"wsu-menu--style-sidebar\">\n<li><a href=\"#ch5-urban-soils\" data-type=\"internal\" data-id=\"#ch5-urban-soils\">Urban Soils<\/a><\/li>\n\n\n\n<li><a href=\"#ch5-soil-quality\" data-type=\"internal\" data-id=\"#ch5-soil-quality\">Soil Quality<\/a><\/li>\n\n\n\n<li><a href=\"#ch5-soil-management\" data-type=\"internal\" data-id=\"#ch5-soil-management\">Soil Management during Construction<\/a><\/li>\n\n\n\n<li><a href=\"#ch5-runoff\" data-type=\"internal\" data-id=\"#ch5-runoff\">Runoff in Urban Soils<\/a><\/li>\n\n\n\n<li><a href=\"#ch5-soil-contamination\" data-type=\"internal\" data-id=\"#ch5-soil-contamination\">Soil Contamination<\/a><\/li>\n\n\n\n<li><a href=\"#ch5-soil-structure\" data-type=\"internal\" data-id=\"#ch5-soil-structure\">Soil Structure and Compaction<\/a><\/li>\n\n\n\n<li><a href=\"#ch5-salinity\" data-type=\"internal\" data-id=\"#ch5-salinity\">Salinity<\/a><\/li>\n\n\n\n<li><a href=\"#ch5-poor-drainage\" data-type=\"internal\" data-id=\"#ch5-poor-drainage\">Poor Drainage<\/a><\/li>\n\n\n\n<li><a href=\"#ch5-extreme-practices\" data-type=\"internal\" data-id=\"#ch5-extreme-practices\">Extreme Practices for Extreme Conditions<\/a><\/li>\n\n\n\n<li><a href=\"#ch5-nutrient-management\" data-type=\"internal\" data-id=\"#ch5-nutrient-management\">Nutrient Management<\/a><\/li>\n\n\n\n<li><a href=\"#ch5-further-reading\" data-type=\"internal\" data-id=\"#ch5-further-reading\">Further Reading<\/a><\/li>\n<\/ul>\n\n<\/div>\r\n\n<\/div>\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\" \/>\n\n\n\n<h2 class=\"wp-block-heading  wsu-heading--style-marked\" id=\"ch5-urban-soils\">Urban Soils<\/h2>\n\n\n\n<p>Soils in urban settings are subjected to a myriad of physical, chemical, and biological disturbances and processes that are fundamentally different than those in agricultural or natural environments. Consider, for example, the intensity of use of, and direct human impacts on, soil in a home landscape, school campus, city park, street tree basin, or other urban horticultural setting (Figure 1). During construction, valuable topsoil may be removed entirely from a site or stockpiled and used later for landscaping. Heavy equipment causes compaction, and construction debris may become mixed with soil. After construction, vehicle and foot traffic impact the physical structure of soils. Petroleum, heavy metals, deicing chemical residues, and other contaminants may enter urban soils and affect chemical and biological processes and properties.<\/p>\n\n\n\n<p>Coupled with a high degree of disturbance and intensity of use, there is a high expectation for performance from urban soils. Homeowners desire attractive landscape plants in yards and around residences and high productivity and food quality in gardens. City parks and school campuses prefer uniform, consistent, weed-free green turf for play areas and healthy trees for cooling shade and beauty. Increasingly, urban soils are valued for the role they play in absorbing and filtering contaminants from urban runoff water. To support these goals, soil may be amended or otherwise altered to support nonadaptive plants and more intensive methods of production and use.<\/p>\n\n\n\n<p>Urban soil management is a rapidly evolving field. Though some solutions and management recommendations for urban soil challenges are offered here, many other options are more complex and outside the scope of this chapter. However, many print and web resources are listed at the end of the chapter in the Further Reading section, and other chapters in this publication include detailed information on specific soil properties and other methods for managing soils and vegetation.<\/p>\n\n\n\n<h2 class=\"wp-block-heading  wsu-heading--style-marked\" id=\"ch5-soil-quality\">Soil Quality<\/h2>\n\n\n\n<p>Quality soil is the foundation of sustainable landscapes. The growth rate, health, and visual appearance of plants are directly related to soil quality. High quality soil is also effective as a filter for contaminants that might otherwise enter groundwater or surface water sources. A fundamental first step in landscape design and installation should be to assess the quality of soil resources on the site. Once characterized, steps should be taken to preserve quality soil for later use during landscaping stages. If quality soil is not present on the site, measures should be taken to improve the resident soil or acquire suitable replacement soil before continuing with landscape establishment.<\/p>\n\n\n<div class=\"wsu-row wsu-spacing-after--large wsu-spacing-before--large wsu-row--halves\" >\r\n    \n<div class=\"wsu-column\"  style=\"\">\r\n\t\n\n<figure class=\"wp-block-image size-full\"><img decoding=\"async\" loading=\"lazy\" width=\"600\" height=\"400\" src=\"https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Figure-1A.jpg\" alt=\"Landscaped trees, shrubs, and grasses grow from rectangular beds between concrete sidewalk and paved street.\" class=\"wp-image-3634\" srcset=\"https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Figure-1A.jpg 600w, https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Figure-1A-300x200.jpg 300w\" sizes=\"(max-width: 600px) 100vw, 600px\" \/><figcaption class=\"wp-element-caption\">Figure 1. Examples of urban soil environments: (top photo) street trees and sidewalk planters in downtown Seattle; (bottom photo) an apartment construction site in Pullman. Photos by R. Koenig.<\/figcaption><\/figure>\n\n<\/div>\r\n\n\n<div class=\"wsu-column\"  style=\"\">\r\n\t\n\n<figure class=\"wp-block-image size-full\"><img decoding=\"async\" loading=\"lazy\" width=\"600\" height=\"400\" src=\"https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Figure-1B.jpg\" alt=\"Construction site of two apartment complexes.\" class=\"wp-image-3635\" srcset=\"https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Figure-1B.jpg 600w, https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Figure-1B-300x200.jpg 300w\" sizes=\"(max-width: 600px) 100vw, 600px\" \/><\/figure>\n\n<\/div>\r\n\n<\/div>\n\n\n<h3 class=\"wp-block-heading\"><em>Assessing Soil Quality and Soil Health<\/em><\/h3>\n\n\n\n<p class=\"wsu-spacing-after--xlarge\">Soil quality is defined by an array of physical, chemical, and biological characteristics known to be important to soil functioning as a medium for plant growth (Table 1). Increasingly, biological parameters are being recognized for their contributions to the overall health of soil. Certain soil quality factors can be assessed using basic soil tests and on-site inspection of the material; others require more elaborate testing. Many physical indicators relate to how soil is handled and placed on the site. It is important that basic soil quality be evaluated before significant investments of time and money are made in the landscape. The adage \u201can ounce of prevention is worth a pound of cure\u201d applies to soil. It is generally easier and less expensive to address soil problems before establishing plants and other landscape features.<\/p>\n\n\n<span id=\"tablepress-123-description\" class=\"tablepress-table-description tablepress-table-description-id-123\">Table 1. Select chemical, physical, and biological indicators of urban soil quality.<\/span>\n\n<table id=\"tablepress-123\" class=\"tablepress tablepress-id-123\" aria-describedby=\"tablepress-123-description\">\n<thead>\n<tr class=\"row-1 odd\">\n\t<th class=\"column-1\">Chemical indicators<\/th><th class=\"column-2\">Physical indicators<\/th><th class=\"column-3\">Biological indicators<\/th>\n<\/tr>\n<\/thead>\n<tbody class=\"row-hover\">\n<tr class=\"row-2 even\">\n\t<td class=\"column-1\">Organic matter content<\/td><td class=\"column-2\">Topsoil depth<\/td><td class=\"column-3\">Microbial activity (respiration)<\/td>\n<\/tr>\n<tr class=\"row-3 odd\">\n\t<td class=\"column-1\">pH<\/td><td class=\"column-2\">Rooting depth\/depth to restrictive layer<\/td><td class=\"column-3\">Earthworm numbers<\/td>\n<\/tr>\n<tr class=\"row-4 even\">\n\t<td class=\"column-1\">Soluble salts (salinity)<\/td><td class=\"column-2\">Structure\/aggregation<\/td><td class=\"column-3\"><span class=\"wsu-screen-reader-only\">Not applicable<\/span><\/td>\n<\/tr>\n<tr class=\"row-5 odd\">\n\t<td class=\"column-1\">Plant nutrient levels<\/td><td class=\"column-2\">Bulk density\/compaction<\/td><td class=\"column-3\"><span class=\"wsu-screen-reader-only\">Not applicable<\/span><\/td>\n<\/tr>\n<tr class=\"row-6 even\">\n\t<td class=\"column-1\">Heavy metal contaminants<\/td><td class=\"column-2\">Infiltration rate<\/td><td class=\"column-3\"><span class=\"wsu-screen-reader-only\">Not applicable<\/span><\/td>\n<\/tr>\n<tr class=\"row-7 odd\">\n\t<td class=\"column-1\">Pesticide residues<\/td><td class=\"column-2\">Water holding capacity<\/td><td class=\"column-3\"><span class=\"wsu-screen-reader-only\">Not applicable<\/span><\/td>\n<\/tr>\n<tr class=\"row-8 even\">\n\t<td class=\"column-1\">Petroleum residues<\/td><td class=\"column-2\">Drainage<\/td><td class=\"column-3\"><span class=\"wsu-screen-reader-only\">Not applicable<\/span><\/td>\n<\/tr>\n<tr class=\"row-9 odd\">\n\t<td class=\"column-1\"><span class=\"wsu-screen-reader-only\">Not applicable<\/span><\/td><td class=\"column-2\">Aeration (gas exchange)<\/td><td class=\"column-3\"><span class=\"wsu-screen-reader-only\">Not applicable<\/span><\/td>\n<\/tr>\n<tr class=\"row-10 even\">\n\t<td class=\"column-1\"><span class=\"wsu-screen-reader-only\">Not applicable<\/span><\/td><td class=\"column-2\">Presence of construction debris<\/td><td class=\"column-3\"><span class=\"wsu-screen-reader-only\">Not applicable<\/span><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<!-- #tablepress-123 from cache -->\n\n\n\n<p class=\"wsu-spacing-before--xlarge\">At a minimum, soil should be tested for the properties described in Table 2, and regional soil guidelines for the plant species being grown should be followed.<\/p>\n\n\n\n<p>Soil properties vary considerably throughout Washington. For example, soil quality guidelines or recommendations applicable for areas west of the Cascades may be difficult and expensive to achieve in arid central Washington and will likely not be sustainable even if achieved. Also, plant materials adapted to a region of Washington may require region-specific soil conditions like pH or salinity. General soil quality guidelines for different regions in Washington are summarized in Table 2. If soils fall outside the recommendations for one or more of the established parameters, consider making improvements before proceeding with landscaping. Similarly, consider employing remedial measures like selecting adapted plant materials and modifying installation techniques for landscape plants (discussed below and in other chapters of this publication).<\/p>\n\n\n<span id=\"tablepress-161-description\" class=\"tablepress-table-description tablepress-table-description-id-161\">Table 2. A summary of topsoil quality guidelines for landscaping in different areas of Washington State.<sup>1<\/sup><\/span>\n\n<table id=\"tablepress-161\" class=\"tablepress tablepress-id-161\" aria-describedby=\"tablepress-161-description\">\n<thead>\n<tr class=\"row-1 odd\">\n\t<th class=\"column-1\"><span class=\"wsu-screen-reader-only\">Not applicable<\/span><\/th><th class=\"column-2\"><span class=\"wsu-screen-reader-only\">Not applicable<\/span><\/th><th class=\"column-3\">West of Cascades<\/th><th class=\"column-4\">Central WA arid areas<\/th><th class=\"column-5\">Eastern WA<\/th>\n<\/tr>\n<\/thead>\n<tbody class=\"row-hover\">\n<tr class=\"row-2 even\">\n\t<td class=\"column-1\">Soil property<\/td><td class=\"column-2\">Units<\/td><td class=\"column-3\">Guideline value or range<\/td><td class=\"column-4\"><span class=\"wsu-screen-reader-only\">Not applicable<\/span><\/td><td class=\"column-5\"><span class=\"wsu-screen-reader-only\">Not applicable<\/span><\/td>\n<\/tr>\n<tr class=\"row-3 odd\">\n\t<td class=\"column-1\">Soluble salts<\/td><td class=\"column-2\">dS\/m or mmhos\/cm<\/td><td class=\"column-3\">Less than 0.5<\/td><td class=\"column-4\">Less than 2.0<\/td><td class=\"column-5\">Less than 1.0<\/td>\n<\/tr>\n<tr class=\"row-4 even\">\n\t<td class=\"column-1\">pH<\/td><td class=\"column-2\">No units<\/td><td class=\"column-3\">5.5 to 7.0<\/td><td class=\"column-4\">6.5 to 7.5<\/td><td class=\"column-5\">5.5 to 7.5<\/td>\n<\/tr>\n<tr class=\"row-5 odd\">\n\t<td class=\"column-1\">Sodium adsorption ratio<\/td><td class=\"column-2\">No units<\/td><td class=\"column-3\">Less than 10<\/td><td class=\"column-4\"><span class=\"wsu-screen-reader-only\">Not applicable<\/span><\/td><td class=\"column-5\"><span class=\"wsu-screen-reader-only\">Not applicable<\/span><\/td>\n<\/tr>\n<tr class=\"row-6 even\">\n\t<td class=\"column-1\">Organic matter<\/td><td class=\"column-2\">% by weight<\/td><td class=\"column-3\">Greater than 5.0<\/td><td class=\"column-4\">Greater than 1.0<\/td><td class=\"column-5\">Greater than 2.0<\/td>\n<\/tr>\n<tr class=\"row-7 odd\">\n\t<td class=\"column-1\">Texture class<\/td><td class=\"column-2\">No units<\/td><td class=\"column-3\">Loam, silt loam, sandy loam, <br \/>\nsandy clay loam, clay loam, <br \/>\nor silty clay loam<\/td><td class=\"column-4\"><span class=\"wsu-screen-reader-only\">Not applicable<\/span><\/td><td class=\"column-5\"><span class=\"wsu-screen-reader-only\">Not applicable<\/span><\/td>\n<\/tr>\n<tr class=\"row-8 even\">\n\t<td class=\"column-1\">Sand content<\/td><td class=\"column-2\">%<\/td><td class=\"column-3\">Less than 70<\/td><td class=\"column-4\"><span class=\"wsu-screen-reader-only\">Not applicable<\/span><\/td><td class=\"column-5\"><span class=\"wsu-screen-reader-only\">Not applicable<\/span><\/td>\n<\/tr>\n<tr class=\"row-9 odd\">\n\t<td class=\"column-1\">Silt content<\/td><td class=\"column-2\">%<\/td><td class=\"column-3\">Less than 70<\/td><td class=\"column-4\"><span class=\"wsu-screen-reader-only\">Not applicable<\/span><\/td><td class=\"column-5\"><span class=\"wsu-screen-reader-only\">Not applicable<\/span><\/td>\n<\/tr>\n<tr class=\"row-10 even\">\n\t<td class=\"column-1\">Clay content<\/td><td class=\"column-2\">%<\/td><td class=\"column-3\">Less than 30<\/td><td class=\"column-4\"><span class=\"wsu-screen-reader-only\">Not applicable<\/span><\/td><td class=\"column-5\"><span class=\"wsu-screen-reader-only\">Not applicable<\/span><\/td>\n<\/tr>\n<tr class=\"row-11 odd\">\n\t<td class=\"column-1\">Coarse fragments<br \/>\n(&gt;1 inch diameter)<\/td><td class=\"column-2\">%<\/td><td class=\"column-3\">Less than 10<\/td><td class=\"column-4\"><span class=\"wsu-screen-reader-only\">Not applicable<\/span><\/td><td class=\"column-5\"><span class=\"wsu-screen-reader-only\">Not applicable<\/span><\/td>\n<\/tr>\n<tr class=\"row-12 even\">\n\t<td class=\"column-1\">Depth<sup>2<\/sup><\/td><td class=\"column-2\">Inches<\/td><td class=\"column-3\">Minimum of 4 for turf; <br \/>\n8 for trees and shrubs<\/td><td class=\"column-4\"><span class=\"wsu-screen-reader-only\">Not applicable<\/span><\/td><td class=\"column-5\"><span class=\"wsu-screen-reader-only\">Not applicable<\/span><\/td>\n<\/tr>\n<tr class=\"row-13 odd\">\n\t<td class=\"column-1\">Nutrient levels<\/td><td class=\"column-2\">Various<\/td><td class=\"column-3\">Reported with recommendations <br \/>\nto correct deficiencies<\/td><td class=\"column-4\"><span class=\"wsu-screen-reader-only\">Not applicable<\/span><\/td><td class=\"column-5\"><span class=\"wsu-screen-reader-only\">Not applicable<\/span><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<!-- #tablepress-161 from cache -->\n\n\n\n<p class=\" wsu-font-size--xsmall\"><sup>1<\/sup>A reference to a list of testing labs in the Pacific Northwest is included in the Further Reading section at the end of this chapter.<br><sup>2<\/sup>Subsoil depth is also an important consideration for deep-rooted plants like trees.<\/p>\n\n\n<div class=\"wsu-accordion wsu-accordion--size-small wsu-spacing-after--large\">\r\n    <h3 id=\"unique-id-1__75908\" class=\"wsu-accordion__title\">\r\n        <button class=\"wsu-accordion__title-button wsu-accordion--toggle\" aria-expanded=\"false\" aria-controls=\"unique-id-1__content\"><strong>Table 2 Extended Description<\/strong><\/button>\r\n    <\/h3>\r\n    <div id=\"unique-id-1__content\" class=\"wsu-accordion__content\" aria-labelledby=\"unique-id-1__75908\">\r\n        <div class=\"wsu-accordion__content-inner\">\r\n            \n\n<p>Table 2 summarizes topsoil quality guidelines for landscaping across three regions of Washington State: west of the Cascades, central Washington arid areas, and eastern Washington. It outlines recommended ranges or thresholds for various soil properties, along with their measurement units.<\/p>\n\n\n\n<p>For soluble salts, measured in dS\/m or mmhos\/cm, recommended levels are less than 0.5 west of the Cascades, less than 2.0 in central Washington arid areas, and less than 1.0 in eastern Washington. Soil pH has no units and should range from 5.5 to 7.0 west of the Cascades, 6.5 to 7.5 in central Washington arid areas, and 5.5 to 7.5 in eastern Washington. The sodium adsorption ratio, also unitless, should be less than 10.<\/p>\n\n\n\n<p>Organic matter, expressed as a percentage by weight, should be greater than 5.0% west of the Cascades, greater than 1.0% in central Washington arid areas, and greater than 2.0% in eastern Washington. Acceptable soil texture classes include loam, silt loam, sandy loam, sandy clay loam, clay loam, and silty clay loam.<\/p>\n\n\n\n<p>For soil particle composition, sand content should be less than 70%, silt content less than 70%, and clay content less than 30%. Coarse fragments larger than 1 inch in diameter should make up less than 10% of the soil.<\/p>\n\n\n\n<p>Recommended soil depth, measured in inches, is a minimum of 4 inches for turf and 8 inches for trees and shrubs. Nutrient levels are not specified numerically but should be determined through soil testing and reported with recommendations to correct any deficiencies.<\/p>\n\n\n\n<p>The table also includes two notes. One indicates that a list of testing laboratories in the Pacific Northwest is available in the further reading section of the source document. The other notes that subsoil depth is an important consideration, particularly for deep-rooted plants such as trees.<\/p>\n\n        <\/div>\r\n    <\/div>\r\n<\/div>\n\n\n<h3 class=\"wp-block-heading\"><em>Preserving Quality Soil<\/em><\/h3>\n\n\n\n<p>Quality soil is a limited resource that should be maintained whenever possible. During construction, the resident soil may be stripped and stockpiled for use later during landscaping. If the resident soil is of adequate quality, this is the most desirable option. Retaining and reusing the native soil on-site is less expensive than importing new soil and will reduce potential problems associated with texture and other differences between imported and resident soil. Through judicious planning, it is also possible to increase the depth of quality soil on finished landscape areas by preserving soil originally covering sites intended for buildings and hardscape surfaces and then redistributing this soil over landscaped areas (Figure 2). See sidebar Depth-to-Volume Relationships for Landscape Soils for information on how to assess available soil resources.<\/p>\n\n\n\n<p>Before construction begins, inventory soil resources on the site. Looking at soil survey reports will provide baseline information to help understand what types of soils are present. Information about soil located on a site can be obtained through the USDA Natural Resources Conservation Service\u2019s online Web Soil Survey (WSS).<\/p>\n\n\n<div class=\"wp-block-image wsu-spacing-after--none\">\n<figure class=\"alignright size-full is-resized\"><img decoding=\"async\" loading=\"lazy\" src=\"https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Figure-2-2.jpg\" alt=\"Large mound of soil surrounding by heavy tread made by large machinery.\" class=\"wp-image-3636\" width=\"450\" height=\"300\" srcset=\"https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Figure-2-2.jpg 600w, https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Figure-2-2-300x200.jpg 300w\" sizes=\"(max-width: 450px) 100vw, 450px\" \/><figcaption class=\"wp-element-caption\">Figure 2. Soil stored in a large stockpile on a residential construction site. Photo by R. Koenig.<\/figcaption><\/figure><\/div>\n\n\n<p>Consider developing a soil management plan describing how soil will be removed, stockpiled, and reapplied during final landscaping of the site. Begin by identifying areas that can be preserved without disturbance and partition or separate these locations from areas where construction activities and equipment will be concentrated. In areas scheduled for disturbance, measure the depth of the original topsoil layer by performing minor excavation at several locations with a soil probe or shovel. Topsoil depths vary widely throughout Washington but are relatively easy to identify based on their dark color and texture. Specify that the topsoil be removed to the prescribed depth and stockpiled separately from subsoil to prevent mixing of these materials (Figure 2).<\/p>\n\n\n\n<p>Research has shown that when soil is stored in large piles for long periods of time, structure is damaged and density (compaction) increases, organic matter levels decline, key beneficial organisms and overall biological activity decreases, and other undesirable chemical changes occur. Weeds may also colonize stockpiled soil, causing problems later in the landscape. To preserve soil quality in stockpiles, consider storing soil in several smaller piles placed at strategic locations on or adjacent to the site. If possible, make stockpiles no more than six feet tall. Plant an annual on the piles or cover them with a layer of organic mulch rather than plastic to help stabilize the material. Vegetation and mulch cover helps control weeds, contribute some organic matter to the soil, and helps sustain biological activity. Annual small grains such as wheat, barley, and oats or legumes like peas make good cover crops for stockpiles since they can establish rapidly and do not become weeds later when the soil is used in the landscape. Finally, reduce handling of topsoil and the length of time the material is stored in stockpiles.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><em>Improving Soil Quality<\/em><\/h3>\n\n\n\n<p>In some situations, quality topsoil may have been removed from a site or the resident soil is of poor quality or insufficient depth. In these cases, additional soil may need to be imported or brought into the site. Locating acceptable replacement soil can be difficult and costly. Test the replacement soil and compare its characteristics to local guidelines or standards such as those in Table 2 and to the quality of resident soil on-site before making purchasing decisions. One of the most important considerations is to ensure that the texture of the replacement soil closely matches the original topsoil or at least does not differ substantially from the subsoil base on which the topsoil will be placed. Contrasting textures (sand over clay, for example) will interfere with water movement and root growth.<\/p>\n\n\n\n<p>Imported topsoil should be free of noxious weeds or other invasives and should not be treated with persistent herbicides. It is difficult and expensive to test for weed seeds and herbicides. Ask the supplier if the material was treated to control weeds and if so what the residual or plant back restriction time is for the chemical(s) used.<\/p>\n\n\n\n<p>If adequate replacement soil cannot be identified, it may be easier or less expensive to improve the soil on-site. Soil can be amended to increase organic matter content, available plant nutrients, and the pH can be changed (changing the acidity or alkalinity). It is extremely difficult to amend soil to change sand, silt, and clay content, which determine the soil textural class. Adding organic matter is the most common amendment used to improve soil physical conditions before establishing permanent vegetation. Some recommendations call for unusually high rates (\u2153 by volume, for example) of organic matter addition. In normal landscape situations, consider reasonable rates of organic matter addition based on guidelines identified in Table 2. Recognize that organic matter decomposes over time and may result in settling and compaction if amended levels in soil are substantially above what can be sustained under normal contributions from plants growing in the landscape. <\/p>\n\n\n<div class=\"wsu-callout wsu-border--add-left wsu-callout--style-basic wsu-color-background--gray-5 wsu-align-item--left wsu-max-width--large wsu-spacing-before--large wsu-spacing-after--large wsu-border--color-vineyard\" >\r\n        \n\n<h4 class=\"wp-block-heading has-text-align-center\">Depth-to-Volume Relationships for Landscape Soils<\/h4>\n\n\n\n<p class=\" wsu-font-size--medium wsu-max-width--xmedium wsu-align-item--center\">The soil management plan should include a survey of depth and volume of quality topsoil on-site before construction begins. When assessing the site, determine the average depth of topsoil that will be preserved for landscaping. Also, determine the square footage of area covered by the soil. One inch of material covering a 1,000 square foot area is equivalent to 3 cubic yards volume. Estimate the total volume of the topsoil resource in cubic feet according to the following equation:<\/p>\n\n\n\n<p class=\"has-text-align-center  wsu-font-size--medium wsu-max-width--xxmedium\">______ inches of topsoil \u00d7 ______ square feet of area \u00d7 0.003 = ______ cubic yards<\/p>\n\n\n\n<p class=\"has-text-align-center  wsu-font-size--medium wsu-max-width--xmedium\">Next, from the landscape plan, determine the square footage of area that will be covered by the preserved soil. Calculate the depth of topsoil coverage for the landscaped area according to the following equation:<\/p>\n\n\n\n<p class=\"has-text-align-center  wsu-font-size--medium wsu-max-width--xxmedium\">______ cubic yards \u00f7 ______ square feet of area \u00f7 0.003 = ______ inches of coverage<\/p>\n\n\n\n<p class=\"has-text-align-center  wsu-font-size--medium wsu-max-width--xxmedium\">This is an estimate of the final depth of topsoil if the material is stockpiled before construction begins and later redistributed on the landscaped areas.<\/p>\n\n<\/div>\r\n\n\n\n<h3 class=\"wp-block-heading\"><em>Special Considerations for Trees<\/em><\/h3>\n\n\n\n<p>Most research suggests that there is no benefit from amending backfill soil to improve quality in routine tree plantings. There may be some benefit associated with loosening the soil in a larger volume of backfill to encourage better rooting. Amending backfill soil can create textural, structural, and other compatibility issues between the backfill and native soil. This may create barriers to root growth and water movement, at times resulting in water saturation of the backfill material and root system in the planting hole. Tree roots eventually have to extend beyond the backfill soil into the native soil. If the tree species is not adapted to the native soil conditions, amending the backfill is not likely to improve tree survival once roots grow into the native soil. In special cases such as tree vaults installed in urban areas, backfill soil may be amended or designed for specific water retention and drainage needs.<\/p>\n\n\n\n<h2 class=\"wp-block-heading  wsu-heading--style-marked\" id=\"ch5-soil-management\">Soil Management during Construction<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\"><em>Controlling Erosion<\/em><\/h3>\n\n\n<div class=\"wp-block-image wsu-spacing-after--none\">\n<figure class=\"alignright size-full is-resized\"><img decoding=\"async\" loading=\"lazy\" src=\"https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Figure-3-2.jpg\" alt=\"Spiderwebbing, small rivulets run through bare soil downhill from a new development.\" class=\"wp-image-3638\" width=\"450\" height=\"300\" srcset=\"https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Figure-3-2.jpg 600w, https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Figure-3-2-300x200.jpg 300w\" sizes=\"(max-width: 450px) 100vw, 450px\" \/><figcaption class=\"wp-element-caption\">Figure 3. Uncontrolled erosion from a residential construction site. Sediment has completely filled in the street gutter. Photo courtesy of USDA-NRCS.<\/figcaption><\/figure><\/div>\n\n\n<p>Soil erosion is a major concern during construction. Large areas of bare soil may be exposed to rain and wind during construction. Dust is a nuisance as well as health issue. Sediment that runs off can have significant offsite impacts such as filling gutters and storm drains, and degrading stream (or other water bodies) water quality (Figure 3). State and local ordinances require that measures be taken to minimize soil erosion from construction sites. Erosion control can be accomplished by implementing one or more best management practices (BMPs) designed to (a) reduce erosion and (b) retain eroded sediment on-site (Figure 4).<\/p>\n\n\n\n<p class=\"wsu-spacing-after--xsmall\">Some BMPs for reducing erosion:<\/p>\n\n\n\n<ul>\n<li>Schedule construction during periods of lower erosion potential (generally, May 1\u2013October 1 in Washington);<\/li>\n\n\n\n<li>Locate potential sediment source areas (stockpiles, access roads, etc.) away from steep slopes and areas that drain into surface water sources or conveyance systems;<\/li>\n\n\n\n<li>Limit disturbance to areas essential to construction; preserve and protect existing vegetation with fences, walls, or other barriers;<\/li>\n\n\n\n<li>Cover small stockpiles of soil with a tarp; vegetate or cover larger stockpiles with a layer of organic mulch.<\/li>\n<\/ul>\n\n\n<div class=\"wsu-row wsu-spacing-after--large wsu-spacing-before--large wsu-row--halves\" >\r\n    \n<div class=\"wsu-column\"  style=\"\">\r\n\t\n\n<figure class=\"wp-block-image size-full\"><img decoding=\"async\" loading=\"lazy\" width=\"600\" height=\"400\" src=\"https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Figure-4A.jpg\" alt=\"A short, black barrier alongside a road is staked upright, downhill from new construction.\" class=\"wp-image-3639\" srcset=\"https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Figure-4A.jpg 600w, https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Figure-4A-300x200.jpg 300w\" sizes=\"(max-width: 600px) 100vw, 600px\" \/><figcaption class=\"wp-element-caption\">Figure 4. Common erosion control measures on construction sites: (left) silt fence used to control gradual (sheet) runoff and erosion, and (right) sediment basin for retaining concentrated flow. Photos taken by R. Koenig.<\/figcaption><\/figure>\n\n<\/div>\r\n\n\n<div class=\"wsu-column\"  style=\"\">\r\n\t\n\n<figure class=\"wp-block-image size-full\"><img decoding=\"async\" loading=\"lazy\" width=\"600\" height=\"400\" src=\"https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Figure-4B.jpg\" alt=\"Sediment basin with water pooling at the base of a hill.\" class=\"wp-image-3640\" srcset=\"https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Figure-4B.jpg 600w, https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Figure-4B-300x200.jpg 300w\" sizes=\"(max-width: 600px) 100vw, 600px\" \/><\/figure>\n\n<\/div>\r\n\n<\/div>\n\n\n<p class=\"wsu-spacing-after--xsmall\">Some BMPs for retaining eroded sediment:<\/p>\n\n\n\n<ul>\n<li>Place fabric fence or straw bale barriers to capture gradual (sheet) runoff;<\/li>\n\n\n\n<li>Install sediment basins, check dams, or retaining walls to interrupt concentrated flow and prevent gully erosion on steep slopes.<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\"><em>Soil Disturbance and Replacement<\/em><\/h3>\n\n\n\n<p>The conditions under which topsoil is removed, stored, and replaced affect future landscaping options and success. Compaction of subsoils during construction also affects the physical condition of soils and subsequent water movement and root growth. During construction, topsoil may become mixed with less desirable subsoil, and the final product may include synthetic materials such as concrete, asphalt, wood, and other debris common in urban environments. These issues are relatively easy to address in a topsoil management plan and are discussed in greater detail below.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><em>Addressing Compaction<\/em><\/h3>\n\n\n<div class=\"wp-block-image wsu-spacing-after--none\">\n<figure class=\"alignright size-full is-resized\"><img decoding=\"async\" loading=\"lazy\" src=\"https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Figure-5-3.jpg\" alt=\"A thin layer of darker soil abuts a layer of lighter-colored soil. Heavy machinery tread is apparent in both layers.\" class=\"wp-image-3642\" width=\"450\" height=\"300\" srcset=\"https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Figure-5-3.jpg 600w, https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Figure-5-3-300x200.jpg 300w\" sizes=\"(max-width: 450px) 100vw, 450px\" \/><figcaption class=\"wp-element-caption\">Figure 5. Topsoil layered over subsoil during final site grading and preparation for planting. Photo taken by R Koenig.<\/figcaption><\/figure><\/div>\n\n\n<p>Construction activities and equipment will compact soil on the site. Compaction, as well as abrupt changes in soil texture and organic matter content between the topsoil and subsoil, can inhibit rooting depth and water flow in the finished landscape. Before spreading topsoil, use a heavy-duty rotary tiller or tractor-mounted implement with a deep ripper or chisel blade to fracture compacted subsoils (preferably when the soils are dry). The depth of tillage required is a function of the depth of compaction. Inspect subsoils on-site and use the appropriate implement capable of fracturing compacted soil to the necessary depth.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><em>Placing Topsoil after Construction<\/em><\/h3>\n\n\n\n<p>To address differences in texture, structure, and organic matter content between subsoils and topsoils, soil should be replaced on the site in layers or lifts (Figure 5). First, spread approximately one-third of the total replacement topsoil depth and incorporate or mix this into the subsoil with a rotary tiller. Spread the remaining soil on top of this \u201ctransitional\u201d layer.<\/p>\n\n\n<div class=\"wp-block-image wsu-spacing-after--none\">\n<figure class=\"alignright size-full is-resized\"><img decoding=\"async\" loading=\"lazy\" src=\"https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Figure-6-1.jpg\" alt=\"A depression in the landscape with pooling water.\" class=\"wp-image-3643\" width=\"450\" height=\"300\" srcset=\"https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Figure-6-1.jpg 600w, https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Figure-6-1-300x200.jpg 300w\" sizes=\"(max-width: 450px) 100vw, 450px\" \/><figcaption class=\"wp-element-caption\">Figure 6. A stormwater catchment and infiltration basin in Pullman, Washington. These basins are now common sights in new residential and commercial developments. Photo by R. Koenig.<\/figcaption><\/figure><\/div>\n\n\n<h2 class=\"wp-block-heading  wsu-heading--style-marked\" id=\"ch5-runoff\">Runoff in Urban Soils<\/h2>\n\n\n\n<p>Controlling and treating runoff water is an increasing concern in urban areas. In addition to sediment, nutrients and pesticides from urban landscapes and petroleum residues from road and parking lot surfaces can be transported in urban runoff water. New and existing commercial and residential developments in many parts of Washington are now required to develop stormwater management plans (Figure 6). Various agencies have prepared detailed guidelines and BMPs to improve urban stormwater retention and quality. Specific information can be found in the stormwater manuals for eastern and western Washington:<\/p>\n\n\n\n<ul>\n<li><a rel=\"noreferrer noopener\" href=\"https:\/\/fortress.wa.gov\/ecy\/ezshare\/wq\/Permits\/Flare\/2019SWMMWW\/2019SWMMWW.htm\" data-type=\"URL\" data-id=\"https:\/\/fortress.wa.gov\/ecy\/ezshare\/wq\/Permits\/Flare\/2019SWMMWW\/2019SWMMWW.htm\" target=\"_blank\">2019 Stormwater Management Manual for Western Washington (opens in new window)<\/a><\/li>\n\n\n\n<li><a rel=\"noreferrer noopener\" href=\"https:\/\/fortress.wa.gov\/ecy\/ezshare\/wq\/Permits\/Flare\/2019SWMMEW\/2019SWMMEW.htm\" data-type=\"URL\" data-id=\"https:\/\/fortress.wa.gov\/ecy\/ezshare\/wq\/Permits\/Flare\/2019SWMMEW\/2019SWMMEW.htm\" target=\"_blank\">2019 Stormwater Management Manual for Eastern Washington (opens in new window)<\/a><\/li>\n<\/ul>\n\n\n\n<p class=\"wsu-spacing-after--xsmall\">Stormwater management programs are designed to promote infiltration, filtration, and detainment of urban waters. BMPs in these areas include:<\/p>\n\n\n\n<ul>\n<li>Installation of trenches, basins, and porous pavement surfaces to promote water infiltration;<\/li>\n\n\n\n<li>Creation of vegetative strips, grassed swales, and sand traps to filter sediment and contaminants;<\/li>\n\n\n\n<li>Creation of impoundments, ponds, and constructed wetlands to detain runoff water, allow sediment to settle out, and filter nutrients and other contaminants.<\/li>\n<\/ul>\n\n\n\n<p>Several routine soil management practices can reduce runoff from urban landscapes. The <a rel=\"noreferrer noopener\" href=\"https:\/\/www.soilsforsalmon.org\/\" data-type=\"URL\" data-id=\"https:\/\/www.soilsforsalmon.org\/\" target=\"_blank\">Soils for Salmon (opens in new window)<\/a>  program promotes the use of compost to amend urban soils to a target 10% organic matter content. Higher soil organic matter contents improve water infiltration into soil and reduce runoff. Aeration (or aerification) also promotes water infiltration in compacted turfgrass soils. Maximizing the use of mulch or compost in bare soil areas and around perennial vegetation also promotes water infiltration and reduces sediment runoff.<\/p>\n\n\n\n<h2 class=\"wp-block-heading  wsu-heading--style-marked\" id=\"ch5-soil-contamination\">Soil Contamination<\/h2>\n\n\n\n<p>Urban soils may contain physical and chemical contaminants not found in natural soil environments. Bulky but relatively inert materials, such as concrete, asphalt, steel, plastics, wood, and glass, pose physical problems if they interfere with landscaping activities or plant rooting, soil drainage, aeration, and water holding capacity. Proper collection and disposal of large debris during and after construction can reduce future landscape problems. Chemical contaminants, such as pesticides, polychlorinated biphenyls (PCBs), and petroleum products, are a larger concern in that their presence cannot be determined visually, and they may impact human as well as plant health.<\/p>\n\n\n\n<p>Surveys comparing urban landscape soils to their native counterparts reveal consistently higher levels of potentially toxic inorganic elements such as copper, cadmium, lead, nickel, and arsenic in the urban environment. Sources of these contaminants include lead-based paint, leaded gasoline, treated wood products, and the long-term use of certain soil amendments high in contaminants.<\/p>\n\n\n\n<p>Many landscape plants can tolerate relatively high levels of inorganic contaminants without adversely affecting growth. Inorganic contaminants are a greater problem in areas where children play, where exposed soils are a source of dust, and in gardens where vegetables may be grown for human consumption. If the history of a site is not known or the presence of inorganic contaminants is suspected, a relatively inexpensive soil test is recommended to determine levels of these contaminants. A test for common inorganic contaminants (i.e., heavy metals) will cost approximately $50 per sample. The cost of testing soils for organic contaminants is much higher (hundreds to thousands of dollars per sample), and one usually needs to know or suspect the organic contaminant to focus testing.<\/p>\n\n\n\n<p>Residual herbicides may also be a concern in landscapes located on recently developed agricultural fields or undeveloped urban lots that may have been treated with an herbicide with a long residual effect. Obtaining information on the history of chemical use on a site can prevent future problems with plantings. Testing for residual herbicides may be warranted but is very expensive. Tests for specific classes of herbicides may cost in excess of $200 per sample, and some guidance must be provided to the testing lab on which herbicide class might be present. Certain herbicides may have to be removed from the site or planting delayed until levels decline naturally. In some situations, activated carbon can be added to soil to reduce the activity of herbicides.<\/p>\n\n\n\n<h2 class=\"wp-block-heading  wsu-heading--style-marked\" id=\"ch5-soil-structure\">Soil Structure and Compaction<\/h2>\n\n\n<div class=\"wp-block-image wsu-spacing-after--none\">\n<figure class=\"alignright size-full is-resized\"><img decoding=\"async\" loading=\"lazy\" src=\"https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Figure-7-1.jpg\" alt=\"A compaction trail devoid of turfgrass running through a manicured lawn and landscape.\" class=\"wp-image-3644\" width=\"450\" height=\"300\" srcset=\"https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Figure-7-1.jpg 600w, https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Figure-7-1-300x200.jpg 300w\" sizes=\"(max-width: 450px) 100vw, 450px\" \/><figcaption class=\"wp-element-caption\">Figure 7. A compaction trail in turfgrass on the campus of Utah State University. Photo by R. Koenig.<\/figcaption><\/figure><\/div>\n\n\n<p>Structure is a desirable characteristic in soils and is essential for optimum plant performance. Soils with well-developed structure promote root growth and have good drainage characteristics, optimum water holding capacities, good aeration (gas exchange) properties, and may be conducive for biological organisms like worms, which are a good indicator of soil health. Compaction destroys soil structure and causes significant plant growth problems in urban landscapes. Compaction forces soil particles closer together, reducing pore space and the volume of air and water in soil. Compaction also seals off the soil surface and reduces the amount of air and water entering soil. Reduced gas exchange and, in particular, a low oxygen concentration in the root zone is the primary cause of plant decline in compacted soils. Physical resistance to root growth is a secondary problem with soil compaction.<\/p>\n\n\n\n<p>Compaction is caused by repeated foot or vehicle traffic over the same soil area (Figure 7). The traffic may be associated with construction activities or foot or vehicle traffic in established landscapes. Moist or wet conditions make soils more susceptible to compaction. Fine-textured soils are also more prone to compaction than coarse-textured or sandy soils. In urban landscapes, vibrations caused by vehicle traffic may also aggravate soil compaction problems.<\/p>\n\n\n<div class=\"wp-block-image wsu-spacing-after--none\">\n<figure class=\"alignright size-full is-resized\"><img decoding=\"async\" loading=\"lazy\" src=\"https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Figure-8-1.jpg\" alt=\"Tree roots spiderwebbing at the surface of heavily compacted, bare soil next to a parking lot.\" class=\"wp-image-3645\" width=\"450\" height=\"300\" srcset=\"https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Figure-8-1.jpg 600w, https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Figure-8-1-300x200.jpg 300w\" sizes=\"(max-width: 450px) 100vw, 450px\" \/><figcaption class=\"wp-element-caption\">Figure 8. Tree roots growing at the surface of heavily compacted soil in a parking lot on the campus of Washington State University in Pullman. Photo by R. Koenig.<\/figcaption><\/figure><\/div>\n\n\n<h3 class=\"wp-block-heading\"><em>Identifying Compaction in Urban Landscapes<\/em><\/h3>\n\n\n\n<p>Sparse growth or barren areas of turf are common indicators of soil compaction. Water runoff or dry spots in irrigated turf can also be indicators. Around trees, soil compaction can be manifested by the presence of rooting near the surface, reduced vigor or growth rates, and different growth rates among several trees planted at the same time (Figure 8). Exploring an area with a soil probe, shovel, long-handled screwdriver, or soil penetrometer can help identify soil compaction. Probes should easily enter moist soil that is not compacted. Probe areas that may be compacted as well as normal appearing areas for comparison.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><em>Preventing Compaction<\/em><\/h3>\n\n\n\n<p>Soil compaction during construction is unavoidable but must be addressed during final grading and landscaping phases. Maintenance and renovation activities may also require the use of heavy equipment in established landscapes. Soil compaction may be minimized or avoided by ensuring activities occur when soil is dry and placing a layer of mulch in travel areas. Steel grates and plywood surface treatments can also help limit compaction. Surface brickwork can be used to encourage some vegetative cover in frequent high traffic areas (Figures 9 and 10). The bricks absorb the force of traffic while allowing plant growth in between bricks or through voids in the bricks.<\/p>\n\n\n<div class=\"wsu-row wsu-spacing-after--large wsu-spacing-before--large wsu-row--halves\" >\r\n    \n<div class=\"wsu-column\"  style=\"\">\r\n\t\n\n<figure class=\"wp-block-image size-full\"><img decoding=\"async\" loading=\"lazy\" width=\"600\" height=\"400\" src=\"https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Figure-9.jpg\" alt=\"A parallel track of decorative, surface brickwork in parklike setting.\" class=\"wp-image-3646\" srcset=\"https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Figure-9.jpg 600w, https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Figure-9-300x200.jpg 300w\" sizes=\"(max-width: 600px) 100vw, 600px\" \/><figcaption class=\"wp-element-caption\">Figure 9. Surface brickwork absorbs the compressive forces of traffic and still allows some vegetative growth through voids in the brick. Photo by R. Koenig.<\/figcaption><\/figure>\n\n<\/div>\r\n\n\n<div class=\"wsu-column\"  style=\"\">\r\n\t\n\n<figure class=\"wp-block-image size-full\"><img decoding=\"async\" loading=\"lazy\" width=\"600\" height=\"400\" src=\"https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Figure-10.jpg\" alt=\"Surface pavers through a grassy lawn connect two parallel sidewalks.\" class=\"wp-image-3647\" srcset=\"https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Figure-10.jpg 600w, https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Figure-10-300x200.jpg 300w\" sizes=\"(max-width: 600px) 100vw, 600px\" \/><figcaption class=\"wp-element-caption\">Figure 10. Surface pavers are a low-technology solution to the problem of compaction trails in turfgrass. Photo by R. Koenig.<\/figcaption><\/figure>\n\n<\/div>\r\n\n<\/div>\n\n<div class=\"wp-block-image wsu-spacing-after--none\">\n<figure class=\"alignright size-full is-resized\"><img decoding=\"async\" loading=\"lazy\" src=\"https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Figure-11-1.jpg\" alt=\"Multiple sidewalks leading from various buildings intersect centrally at a large, open area on a university campus. \" class=\"wp-image-3649\" width=\"450\" height=\"300\" srcset=\"https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Figure-11-1.jpg 600w, https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Figure-11-1-300x200.jpg 300w\" sizes=\"(max-width: 450px) 100vw, 450px\" \/><figcaption class=\"wp-element-caption\">Figure 11. Multiple sidewalks dissect a large open area on the campus of Utah State University. Sidewalks were placed to avoid compaction trails created when students walked between buildings. Photo by R. Koenig.<\/figcaption><\/figure><\/div>\n\n\n<p>In established landscapes, consider restricting foot traffic in sensitive or compaction-prone areas. Signs alone generally are not very effective in minimizing access, and fences can be visually unappealing. Landscape design methods using vegetation (e.g., shrubs), hardscape (e.g., curbing, railing), or other planned barriers can successfully direct traffic onto sidewalks and away from sensitive soil areas. In turf areas where compaction appears in defined paths consider adding a sidewalk (Figure 11). An alternative would be to use a surface treatment, such as a mulch layer, to improve path appearance. Grates and surface mulch layers also reduce soil compaction around the base of trees. The installation of compaction-resistant soil may be necessary in certain situations. More information on compaction-resistant soil can be found in the section <a href=\"#ch5-extreme-practices\" data-type=\"internal\" data-id=\"#ch5-extreme-practices\">Extreme Practices for Extreme Conditions<\/a>.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><em>Treating Compaction<\/em><\/h3>\n\n\n\n<p>Subsoiling or deep ripping using agricultural or other heavy tillage implements may be necessary in heavily compacted areas, especially after construction and before installing landscape features and irrigation systems. In established turfgrass areas, compacted soil can be aerated with a hollow tine aerator that removes small cores of soil. Aeration should be performed at least once a year in turfgrass areas subjected to heavy traffic, and more frequently in areas prone to developing compaction trails. A thin (less than \u00bd inch) layer of fine organic matter can be spread immediately after aerating to backfill the holes created by the implement. Mowing or raking the area can help fill the holes with organic matter. In severely compacted turfgrass trails, the addition of at least one inch of organic matter followed by tillage with a rotary tiller and reseeding or sodding may be required. Measures should be taken to limit traffic in the area while turfgrass reestablishes and to prevent compaction from recurring in the future.<\/p>\n\n\n\n<p>Treating compaction around trees and other woody perennials is difficult without damaging the root system. Implements have been developed to inject water or air under high pressure to fracture compacted soil in the root zone of trees, though research has shown mixed results with these methods. Placing a thick layer of coarse organic mulch can help limit further compaction and, over time, improve compacted soil conditions. Vertical mulching and radial trenching are other possible approaches to treating severe compaction in the root zone of trees. These are described in the section <a href=\"#ch5-extreme-practices\" data-type=\"internal\" data-id=\"#ch5-extreme-practices\">Extreme Practices for Extreme Conditions<\/a>. Another option is to select tolerant tree species for areas prone to soil compaction. See the section on selecting tolerant plants in Further Reading at the end of this chapter.<\/p>\n\n\n\n<h2 class=\"wp-block-heading  wsu-heading--style-marked\" id=\"ch5-salinity\">Salinity<\/h2>\n\n\n<div class=\"wp-block-image wsu-spacing-after--none\">\n<figure class=\"alignright size-full is-resized\"><img decoding=\"async\" loading=\"lazy\" src=\"https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Figure-12-1.jpg\" alt=\"The receding grass alongside a sidewalk leaves a strip of bare soil.\" class=\"wp-image-3650\" width=\"450\" height=\"300\" srcset=\"https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Figure-12-1.jpg 600w, https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Figure-12-1-300x200.jpg 300w\" sizes=\"(max-width: 450px) 100vw, 450px\" \/><figcaption class=\"wp-element-caption\">Figure 12. Turfgrass damage caused by deicing salts running off of sidewalks. Photo by R. Koenig.<\/figcaption><\/figure><\/div>\n\n\n<p>Salinity is a measure of the total amount of soluble salts in soil. As soluble salt levels increase, it becomes more difficult for plants to extract water from soil. This problem has been referred to as chemical drought, since affected plants show visual symptoms similar to water stress. Soil salinity levels can be assessed with a simple and inexpensive soil test.<\/p>\n\n\n\n<p>Saline (high salt) soils are most common in arid areas of central Washington. However, high soil salinity can occur virtually anywhere because of poor soil drainage, failure to include a leaching fraction with irrigation, use of irrigation water with high levels of salts, application of excessive amounts of fertilizer over time, the cumulative effects of repeated use of manure or compost, or when deicing salts used on sidewalks and roads create runoff which enters the soil (Figure 12).<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><em>Managing Soil Salinity Problems<\/em><\/h3>\n\n\n\n<p>Different plants vary widely in their salt tolerance. One method of addressing a soil salinity problem is to select salt-tolerant vegetation in saline soil areas or areas prone to receiving salts from deicing activities. Several excellent resources are available for selecting plants that tolerate salinity in the root zone. See the section on selecting tolerant plants in Further Reading at the end of this chapter for more information.<\/p>\n\n\n\n<p>Alternative deicing chemicals are available that have fewer harmful impacts on plants than traditional sodium- or calcium chloride-based materials. Calcium magnesium acetate is more expensive but has minimal effect on plants. Abrasive (traction) and dark-colored materials that enhance solar radiation absorption can also be used alone or in combination with salts to melt ice. See the Further Reading section for more information on managing deicing chemicals. Curbing and raised planting areas also serve to channel deicing salts away from soil around plants.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><em>Treating a Saline Soil<\/em><\/h3>\n\n\n\n<p>Soluble salts can be leached (washed) from the soil if there is adequate drainage and a clean source of irrigation water available. Drainage is essential for reclaiming saline soils since water must move through the soil (rather than run off the surface) to leach salts below the plant root zone. Compaction, a restrictive layer (e.g., plow pan or tillage pan), poor structure, or fine (silt or clay) texture can cause poor drainage and must be addressed.<\/p>\n\n\n\n<p>Once drainage has been established, apply clean, fresh water to the site to leach salts. A rule of thumb for leaching salts from the upper 12 inches of the root zone is to apply 6 inches of water to reduce salinity levels by 50%, 12 inches to reduce salinity levels by 80%, and 24 inches to reduce salinity levels by 90%. Based on the initial soil test, estimate the amount of water necessary to reduce salinity to desirable levels for the plants to be grown. The total amount of water necessary should be applied over a period of several days and the soil should be kept moist during the leaching treatment to maintain the downward movement of water. It should also be noted that leaching to remove soluble salts will also move mobile plant nutrients like nitrate-nitrogen out of the profile. These nutrients can become groundwater and surface water contaminants.<\/p>\n\n\n<div class=\"wp-block-image wsu-spacing-after--none\">\n<figure class=\"alignright size-full is-resized\"><img decoding=\"async\" loading=\"lazy\" src=\"https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Figure-13-1.jpg\" alt=\"Rocky soil has been dug out in preparation for a tree planting. Two trees in burlap on their sides rest on the sidewalk. Water has filled the planting hole to the top.\" class=\"wp-image-3651\" width=\"450\" height=\"300\" srcset=\"https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Figure-13-1.jpg 600w, https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Figure-13-1-300x200.jpg 300w\" sizes=\"(max-width: 450px) 100vw, 450px\" \/><figcaption class=\"wp-element-caption\">Figure 13. Water retention in a poorly draining tree hole prepared for planting. Photo by R. Koenig.<\/figcaption><\/figure><\/div>\n\n\n<h2 class=\"wp-block-heading  wsu-heading--style-marked\" id=\"ch5-poor-drainage\">Poor Drainage<\/h2>\n\n\n\n<p>Poor drainage is a common problem in urban landscapes. Virtually any textural change or other contrasting features between different soil types have the potential to impede water flow. Common examples are compaction of subsoils during construction, contrasting textures between topsoil and subsoil, soil layering during placement, and compaction produced during the excavation of tree planting holes (Figure 13).<\/p>\n\n\n\n<p>Poor drainage keeps plants in a perpetually wet soil condition, which restricts aeration (gas exchange properties) in soil and limits oxygen availability to root systems. The result is an increase in the occurrence of root diseases, nutrient (e.g., iron) deficiencies, and other growth problems. Restricted drainage can also make soils more prone to compaction from traffic when soils are moist or wet.<\/p>\n\n\n\n<p>Often, drainage problems can be identified by inspecting the soil before planting. Many fine-textured soils will have drainage problems. The presence of compacted soil layers can be identified using a soil probe, metal rod, shovel, or penetrometer. Water pooling in an area such as a low spot in the landscape or a planting hole also indicates a drainage problem. Ideally, pooled water in a depression or planting hole should drain through the soil within 24 hours.<\/p>\n\n\n\n<p>Certain landscape plants are adapted to poorly drained soil conditions. Species native to swampy environments or areas with a high water table may tolerate such conditions. See the Further Reading section at the end of this chapter for more information on selecting tolerant plants. In areas where poor drainage is a recurring problem, consider selecting plants tolerant of this condition.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><em>Improving Soil Drainage<\/em><\/h3>\n\n\n\n<p class=\"wsu-spacing-after--xsmall\">Several cultural and management practices can be used to alter soil drainage:<\/p>\n\n\n\n<ul>\n<li>Amend soils with organic matter. Organic matter can improve drainage in fine-textured soils. Amending soil with organic matter may improve drainage near the surface, but subsurface drainage may still be a problem if the subsurface layer impedes water movement.<\/li>\n\n\n\n<li>Install subsurface tile drains at a depth above which you want to promote soil drainage. A tile drain is a length of perforated plastic pipe buried one to several feet beneath the soil surface. Excess soil water enters the pipe and is diverted to an open ditch or gutter out of plant root zones. There are many potential and creative uses for subsurface tile drains in landscapes, such as in planting beds, behind retaining walls, or in tree vaults, to name a few.<\/li>\n\n\n\n<li>Install vertical drains in planting holes. A vertical drain or \u201cdry well\u201d is a hole 4 to 6 inches in diameter and 3 to 5 feet deep dug in the bottom of a tree or shrub planting hole. A soil bucket auger or post-hole digger can be used to excavate the hole. The hole is filled with coarse gravel to provide a drainage outlet for water that might otherwise pool in the bottom of a planting area.<\/li>\n\n\n\n<li>Construct raised beds or planting boxes. Raised beds or planting on hills or berms raises a part of the plant root system above the native, poorly drained soil. Beds 8 to 12 inches high are adequate for many garden plants while hills or berms 2 to 3 feet high work better for woody plants.<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading  wsu-heading--style-marked\" id=\"ch5-extreme-practices\">Extreme Practices for Extreme Conditions<\/h2>\n\n\n\n<p>Some urban situations may require more extreme soil management practices. Examples might include changing soil in planting areas where annuals are replaced several times during the growing season. Use of containers, intensively used turfgrass areas, and trees growing in urban settings where pavements and sidewalks limit rooting and surface soil access around trees are other examples. Considerations such as maintaining soil tilth, minimizing compaction, and providing drainage while retaining water and nutrients require creative and intensive solutions. Monitoring moisture and applying irrigation water only during dry periods may also be needed. The following paragraphs describe approaches to extreme conditions in urban soil management. More information can be found in the Further Reading section at the end of this chapter.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><em>Extreme Amending<\/em><\/h3>\n\n\n\n<p>Intensively managed areas, raised beds, and planter boxes or containers where several crops of annuals are grown each year may warrant amending soils with large amounts of organic matter, such as peat moss, bark fines, wood chips, straw or other plant residues, or inorganic materials such as perlite and vermiculite. In fact, growing media in some of these intensive situations may be more similar to soilless growth media used in greenhouses than mineral soil found in landscapes. Such \u201cextreme amending\u201d presents few problems since organic matter and other amendments can be replenished when necessary. This soil amendment method becomes impractical and is not recommended for large areas of the landscape and where perennials will be grown since it is difficult to maintain and amend soils in these situations.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><em>Soil Removal and Replacement<\/em><\/h3>\n\n\n\n<p>When urban soils are contaminated with pesticides or petroleum residues or become severely degraded as a result of compaction and loss of organic matter, soil replacement may be warranted. Soil replacement in annual planting areas is obviously easier than under perennial vegetation. If perennial plants are in such poor condition that they are not worth saving, then replacement of both soil and vegetation should be considered. In situations where very old or valuable trees exist, it may be possible, though difficult, to partially replace soil within the root zone. Before attempting soil replacement, review other options described in this chapter for renovating the soil and improving growing conditions.<\/p>\n\n\n\n<p>Methods for soil replacement around established trees elsewhere (i.e., outside of Washington) are described in the Further Reading section. These methods involved digging a series of four radial trenches beginning 10 feet away from the trunks of large ( greater than 30-inch diameter) trees. Each trench was 10 feet long, 2 feet deep, and 14 inches wide and was positioned in areas without large roots. Trenches were backfilled with a mixture of leaf compost and quality topsoil. Another procedure involved using a combination of pressurized water and a vacuum to dislodge and remove soil with minimal damage to roots. This \u201chydraulic excavation\u201d technique was performed in holes 4 inches in diameter and 24 inches deep spaced from 12 to 30 inches apart in a grid pattern within the drip line (outer edge of the canopy) of trees. Pits were also excavated to a depth of 24 inches and covered up to 65 square feet of area. High quality replacement soil was used to backfill the excavated areas. When done carefully, these extreme measures successfully improved the health and growth rate of established trees.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><em>Using Compaction-Resistant Soils<\/em><\/h3>\n\n\n\n<p>In general, coarse-textured (e.g., sandy) soils are more resistant to compaction than fine-textured (e.g., high silt or clay) soils. In areas where repeated compaction from foot traffic is a problem, the topsoil can be replaced with a sand, loamy sand, or sandy loam texture material. In extreme cases, a medium designed with 20 to 30% soil and the remainder composed of coarse sand or pea gravel is less prone to compaction but can still retain some water and nutrients to support plant growth.<\/p>\n\n\n<div class=\"wp-block-image wsu-spacing-after--none\">\n<figure class=\"alignright size-full is-resized\"><img decoding=\"async\" loading=\"lazy\" src=\"https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Figure-14-3.jpg\" alt=\"A tree surrounded by concrete sidewalk and paved road grows from a small, square island of soil.\" class=\"wp-image-3652\" width=\"450\" height=\"300\" srcset=\"https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Figure-14-3.jpg 600w, https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Figure-14-3-300x200.jpg 300w\" sizes=\"(max-width: 450px) 100vw, 450px\" \/><figcaption class=\"wp-element-caption\">Figure 14. These confined tree plantings on a downtown street in Seattle demanded creative designs to ensure adequate rooting volume, drainage, and access to irrigation water and fertilizer. Photo by R. Koenig.<\/figcaption><\/figure><\/div>\n\n\n<h3 class=\"wp-block-heading\"><em>Container and Vault Plantings<\/em><\/h3>\n\n\n\n<p>Many urban settings have virtually no exposed soil and therefore must rely on traditional container plantings or, in the case of trees, vaults placed belowground to contain the growing medium and root system (Figure 14). Considerations such as sizing for critical soil volume to meet rooting and water needs, open or closed vault systems to permit natural rainfall and drainage, and providing access for fertilization and drainage are important.<\/p>\n\n\n\n<p>Critical vault or container soil volumes for trees are based on providing adequate water between irrigations during dry periods. Various methods have been used to estimate critical soil volumes, which are summarized in a paper written by Lindsey and Bassuk (1991) that is listed in the Further Reading section. In this paper, the authors also describe a method for estimating the soil volume required for trees in different locations. In Seattle, estimates of 1.5 cubic feet of soil volume are required for each square foot of surface area encompassed by the tree\u2019s drip line.<\/p>\n\n\n\n<p>Drainage is a major challenge in container and vault systems. Depending on the configuration of the hardscape, runoff from streets, sidewalks, and other surfaces can substantially increase or decrease the amount of water entering soil.<\/p>\n\n\n\n<p>In addition to providing adequate rooting volume, these units include provisions for irrigation, flushing of salts, drainage, fertilizer injection, and oxygen supply (aeration) to root systems in vaults with minimal surface access and total enclosure. Jewell (1981) notes that no single vault system is appropriate for all situations but that the design should be based on the specific problems expected on the site.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><em>Vertical Mulching<\/em><\/h3>\n\n\n\n<p>Though labor intensive, vertical mulching has been shown to improve the performance of declining trees in urban settings by enhancing soil permeability and air and water movement beneath the compacted soil surface. In practice, two- to four-inch diameter holes are made with an auger in the drip line of the tree. Holes are normally two to three feet deep beginning two feet from the base of the tree and extend in a square grid or five-spoke radial pattern to the edge or slightly beyond the drip line. The holes may be filled with coarse organic or inorganic matter, like wood chips or gravel. Some recommendations call for the addition of slow-release fertilizer with the backfill material.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><em>Special Growing Media for Urban Plantings<\/em><\/h3>\n\n\n\n<p>In order to support structures, sidewalks, road surfaces, and other hardscape features, soil and fill materials must be compacted to prevent settling and shrinking or swelling. The level of compaction required to meet construction standards is high enough to prevent root growth into or through the material. This severely limits the rooting volume of all plants, but especially trees, grown in urban settings. Alternatives to compacting soil and fill materials include using coarse sand or stone as fill. These materials are capable of bearing the loads required for urban structures and surfaces while maintaining some pore space to accommodate root growth. However, these coarse alternatives have relatively low water and nutrient retention properties. Structural soil materials consisting primarily of crushed rock with a diameter of \u00bd to 1\u00bd inch with some soil materials have been tested in research and found to meet bearing standards while also allowing root growth through the material. These alternatives offer the potential to expand rooting volumes of urban plants to areas under hardscape surfaces. References to these alternative structural materials are included at the end of this chapter in the section titled Structural Materials for Tree Root Growth under Pavement.<\/p>\n\n\n\n<h2 class=\"wp-block-heading  wsu-heading--style-marked\" id=\"ch5-nutrient-management\">Nutrient Management<\/h2>\n\n\n\n<p>Fertilization is important for correcting nutrient deficiencies and promoting plant growth. Increasingly, however, nutrient management and fertilization practices are becoming environmental issues in urban settings. Overapplication of lawn and garden fertilizers containing phosphorus and the application of manure and some composted organic materials is resulting in high levels of phosphorus in soil and urban runoff water. In Utah, for example, more than 90% of soil samples from established urban and home landscapes have very high or excessive levels of phosphorus. Beginning in 2011, Washington banned the use of fertilizers containing phosphorus on turf in residential, commercial, and publicly owned land.<\/p>\n\n\n\n<p>Nutrient management and fertilization practices for urban soils are largely the same as for other garden and landscape situations. Fundamentally, nutrient applications should be based on diagnostic soil or plant tissue testing to define nutrient needs, rates calculated to meet these needs, and methods of application used to ensure nutrients remain in the soil.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\" \/>\n\n\n\n<h2 class=\"wp-block-heading  wsu-heading--style-marked\" id=\"ch5-further-reading\">Further Reading<\/h2>\n\n\n\n<p>There are many excellent Extension publications and resources on topics related to urban soil and plant management. Readers are encouraged to search their state\u2019s Extension publication library for more information on this topic.<\/p>\n\n\n\n<h3 class=\"wp-block-heading wsu-spacing-after--small\">Soil Testing Labs Serving the Pacific Northwest<\/h3>\n\n\n\n<p><a href=\"http:\/\/analyticallabs.puyallup.wsu.edu\/analyticallabs\/\" data-type=\"URL\" data-id=\"http:\/\/analyticallabs.puyallup.wsu.edu\/analyticallabs\/\" target=\"_blank\" rel=\"noreferrer noopener\">Washington State Pest Management Resource Service (opens in new window)<\/a>. n.d. Analytical Laboratories and Consultants Serving Agriculture in the Pacific Northwest. Washington State University.<\/p>\n\n\n\n<h3 class=\"wp-block-heading wsu-spacing-after--small\">General Information on Urban Soils and Their Management<\/h3>\n\n\n\n<p>Craul, P.J. 1992. Urban Soil in Landscape Design. John Wiley and Sons, 396 p.<\/p>\n\n\n\n<p>Craul, P.J. 1999. Urban Soils\u2014Applications and Practices. John Wiley and Sons, 366 p.<\/p>\n\n\n\n<p><a href=\"https:\/\/illinoisurbanmanual.org\/\" data-type=\"URL\" data-id=\"https:\/\/illinoisurbanmanual.org\/\" target=\"_blank\" rel=\"noreferrer noopener\">Illinois Urban Manual (opens in new window)<\/a>. 2024. <\/p>\n\n\n\n<p>Soil Science Society of America. 2024. <a rel=\"noreferrer noopener\" href=\"https:\/\/www.soils.org\/\" data-type=\"URL\" data-id=\"https:\/\/www.soils.org\/\" target=\"_blank\">Soil Contaminants (opens in new window)<\/a>.<\/p>\n\n\n\n<p>USDA Natural Resources Conservation Service. n.d. <a href=\"https:\/\/www.nrcs.usda.gov\/conservation-basics\/natural-resource-concerns\/soil\/urban-soils\" data-type=\"URL\" data-id=\"https:\/\/www.nrcs.usda.gov\/conservation-basics\/natural-resource-concerns\/soil\/urban-soils\" target=\"_blank\" rel=\"noreferrer noopener\">Urban Soils (opens in new window)<\/a>.<\/p>\n\n\n\n<p>US Environmental Protection Agency. 2011. <a href=\"https:\/\/www.epa.gov\/sites\/default\/files\/2014-03\/documents\/urban_gardening_fina_fact_sheet.pdf\" data-type=\"URL\" data-id=\"https:\/\/www.epa.gov\/sites\/default\/files\/2014-03\/documents\/urban_gardening_fina_fact_sheet.pdf\" target=\"_blank\" rel=\"noreferrer noopener\">Reusing Potentially Contaminated Landscapes: Growing Gardens in Urban Soils (link to PDF document)<\/a>. <\/p>\n\n\n\n<p><a href=\"https:\/\/www.compostwashington.org\/\" data-type=\"URL\" data-id=\"https:\/\/www.compostwashington.org\/\" target=\"_blank\" rel=\"noreferrer noopener\">Washington Organic Recycling Council (opens in new window)<\/a>. 2024.<\/p>\n\n\n\n<h3 class=\"wp-block-heading wsu-spacing-after--small\">Information on Soil Quality<\/h3>\n\n\n\n<p>Craul, P.J. 1985. A Description of Urban Soils and Their Desired Characteristics. <em>Journal of Arboriculture<\/em> 11(11):330\u2013339.<\/p>\n\n\n\n<p>Koenig, R., and V. Isaman. 2010. <a href=\"https:\/\/digitalcommons.usu.edu\/cgi\/viewcontent.cgi?article=1014&amp;context=extension_curgarden\" data-type=\"URL\" data-id=\"https:\/\/digitalcommons.usu.edu\/cgi\/viewcontent.cgi?article=1014&amp;context=extension_curgarden\" target=\"_blank\" rel=\"noreferrer noopener\">Topsoil Quality Guidelines for Landscaping (opens in new window)<\/a>. <em>Utah State University Extension Publication<\/em>. Utah State University.<\/p>\n\n\n\n<h3 class=\"wp-block-heading wsu-spacing-after--small\">Information on Soil Mapping and Assessment<\/h3>\n\n\n\n<p>USDA Natural Resources Conservation Service. 2019. <a href=\"https:\/\/websoilsurvey.sc.egov.usda.gov\/App\/HomePage.htm\" data-type=\"URL\" data-id=\"https:\/\/websoilsurvey.sc.egov.usda.gov\/App\/HomePage.htm\" target=\"_blank\" rel=\"noreferrer noopener\">Web Soil Survey (opens in new window)<\/a>.<\/p>\n\n\n\n<h3 class=\"wp-block-heading wsu-spacing-after--small\">Information on Soil Amendment and Planting Practices for Trees<\/h3>\n\n\n\n<p>Arnold, M.A., and D.F. Welsh. 1995. Effects of Planting Hole Configuration and Soil Type on Transplant Establishment of Container-Grown Live Oak. <em>Journal of Arboriculture<\/em> 21(4):213\u2013218.<\/p>\n\n\n\n<p>Birdel, R., C. Whitcomb, and B.L. Appleton. 1983. Planting Techniques for Tree Spade Dug Trees. <em>Journal of Arboriculture<\/em> 9(11):282\u2013284.<\/p>\n\n\n\n<p>Corley, W.L. 1984. Soil Amendments at Planting. <em>Journal of Environmental Horticulture<\/em> 2(1):27\u201330.<\/p>\n\n\n\n<p>Smalley, T.J., and C.B. Wood. 1995. Effect of Backfill Amendment on Growth of Red Maple. <em>Journal of Arboriculture<\/em> 21(5):247\u2013249.<\/p>\n\n\n\n<p><a href=\"https:\/\/mortonarb.org\/\" data-type=\"URL\" data-id=\"https:\/\/mortonarb.org\/\" target=\"_blank\" rel=\"noreferrer noopener\">The Morton Arboretum (opens in new window)<\/a>. 2024.<\/p>\n\n\n\n<p>Watson, G.W., P. Kelsey, and K. Woodtli. 1996. Replacing Soil in the Root Zone of Mature Trees for Better Growth. <em>Journal of Arboriculture<\/em> 22(4):167\u2013173.<\/p>\n\n\n\n<p>Watson, G.W., G. Kupkowski, and K.G. von der Heide-Spravka. 1992. The Effect of Backfill Soil Texture and Planting Hole Shape on Root Regeneration of Transplanted Green Ash. <em>Journal of Arboriculture<\/em> 18(3):130\u2013134.<\/p>\n\n\n\n<h3 class=\"wp-block-heading wsu-spacing-after--small\" id=\"ch5-structural-materials\">Structural Materials for Tree Root Growth under Pavement<\/h3>\n\n\n\n<p>American Society of Landscape Architects. 2024. <a href=\"https:\/\/www.asla.org\/ContentDetail.aspx?id=55503\" data-type=\"URL\" data-id=\"https:\/\/www.asla.org\/ContentDetail.aspx?id=55503\" target=\"_blank\" rel=\"noreferrer noopener\">Landscape Architecture Technical Information Series (LATIS) publications (opens in new window)<\/a>.<\/p>\n\n\n\n<p>Cornell University. 2024. <a href=\"https:\/\/blogs.cornell.edu\/urbanhort\/outreach\/\" data-type=\"URL\" data-id=\"https:\/\/blogs.cornell.edu\/urbanhort\/outreach\/\" target=\"_blank\" rel=\"noreferrer noopener\">Urban Horticulture Institute (opens in new window)<\/a>.<\/p>\n\n\n\n<p>Grabosky, J., and N. Bassuk. 1995. A New Urban Tree Soil to Safely Increase Rooting Volumes under Sidewalks. <em>Journal of Arboriculture<\/em> 21(4):187\u2013199.<\/p>\n\n\n\n<p>Kristoffersen, P. 1998. Designing Urban Pavement Sub-bases to Support Trees. <em>Journal of Arboriculture<\/em> 24(3):121\u2013126.<\/p>\n\n\n\n<h3 class=\"wp-block-heading wsu-spacing-after--small\">Information on Compost Quality and Standards for Washington<\/h3>\n\n\n\n<p>Washington State Department of Ecology. n.d. <a href=\"http:\/\/www.ecy.wa.gov\/programs\/swfa\/compost\/\" data-type=\"URL\" data-id=\"http:\/\/www.ecy.wa.gov\/programs\/swfa\/compost\/\" target=\"_blank\" rel=\"noreferrer noopener\">Compost (opens in new window)<\/a>.<\/p>\n\n\n\n<h3 class=\"wp-block-heading wsu-spacing-after--small\">Managing Urban Runoff<\/h3>\n\n\n\n<p><a href=\"https:\/\/mrsc.org\/search-results?q=stormwater\" data-type=\"URL\" data-id=\"https:\/\/mrsc.org\/search-results?q=stormwater\" target=\"_blank\" rel=\"noreferrer noopener\">Municipal Research and Services Center of Washington (opens in new window)<\/a>. 2024. Search for term \u201cstormwater\u201d to get applicable results<\/p>\n\n\n\n<p>US Environmental Protection Agency. <a href=\"https:\/\/www.epa.gov\/nps\/urban-runoff-national-management-measures\" data-type=\"URL\" data-id=\"https:\/\/www.epa.gov\/nps\/urban-runoff-national-management-measures\" target=\"_blank\" rel=\"noreferrer noopener\">Nonpoint Source Pollution\u2014Urban Runoff: National Management Measures (opens in new window)<\/a>.<\/p>\n\n\n\n<p>Washington State Department of Ecology. 2019. <a href=\"https:\/\/fortress.wa.gov\/ecy\/ezshare\/wq\/Permits\/Flare\/2019SWMMEW\/2019SWMMEW.htm\" data-type=\"URL\" data-id=\"https:\/\/fortress.wa.gov\/ecy\/ezshare\/wq\/Permits\/Flare\/2019SWMMEW\/2019SWMMEW.htm\" target=\"_blank\" rel=\"noreferrer noopener\">Stormwater Management Manual for Eastern Washington (opens in new window)<\/a>.<\/p>\n\n\n\n<p>Washington State Department of Ecology. 2019. <a href=\"https:\/\/fortress.wa.gov\/ecy\/ezshare\/wq\/Permits\/Flare\/2019SWMMWW\/2019SWMMWW.htm\" data-type=\"URL\" data-id=\"https:\/\/fortress.wa.gov\/ecy\/ezshare\/wq\/Permits\/Flare\/2019SWMMWW\/2019SWMMWW.htm\" target=\"_blank\" rel=\"noreferrer noopener\">Stormwater Management Manual for Western Washington (opens in new window)<\/a>.<\/p>\n\n\n\n<h3 class=\"wp-block-heading wsu-spacing-after--small\">Soil Volumes and Design Specifications for Tree Vaults<\/h3>\n\n\n\n<p>Jewell, L. 1981. Planting Trees in City Soils. <em>Landscape Architecture<\/em> 71(3):387\u2013389.<\/p>\n\n\n\n<p>Lindsey, P., and N. Bassuk. 1991. Specifying Soil Volumes to Meet the Water Needs of Mature Urban Street Trees and Trees in Containers. <em>Journal of Arboriculture<\/em> 17(6):141\u2013148.<\/p>\n\n\n\n<h3 class=\"wp-block-heading wsu-spacing-after--small\">References on Selecting Plants Tolerant of Specific Soil Conditions<\/h3>\n\n\n\n<p>Kuhns, M., and L. Rupp. 2000. <a href=\"https:\/\/extension.usu.edu\/forestry\/files\/publications\/other-publications\/selecting-and-planting-landscape-trees.pdf\" data-type=\"URL\" data-id=\"https:\/\/extension.usu.edu\/forestry\/files\/publications\/other-publications\/selecting-and-planting-landscape-trees.pdf\" target=\"_blank\" rel=\"noreferrer noopener\">Selecting and Planting Landscape Trees (link to PDF document)<\/a>. <em>Utah State University Extension Publication<\/em> NR-460. Utah State University.<\/p>\n\n\n\n<p>Kotuby-Amacher, J., R. Koenig, and B. Kitchen. 2000. <a href=\"https:\/\/digitalcommons.usu.edu\/cgi\/viewcontent.cgi?article=1042&amp;context=extension_histall\" data-type=\"URL\" data-id=\"https:\/\/digitalcommons.usu.edu\/cgi\/viewcontent.cgi?article=1042&amp;context=extension_histall\" target=\"_blank\" rel=\"noreferrer noopener\">Salinity and Plant Tolerance (opens in new window)<\/a>. <em>Utah State University Extension Publication<\/em> NR-460.<\/p>\n\n\n\n<h3 class=\"wp-block-heading wsu-spacing-after--small\">Information on Deicing Chemicals and Management<\/h3>\n\n\n\n<p>Koenig, R., and L. Rupp. 1999. <a href=\"https:\/\/digitalcommons.usu.edu\/cgi\/viewcontent.cgi?article=1730&amp;context=extension_histall\" data-type=\"URL\" data-id=\"https:\/\/digitalcommons.usu.edu\/cgi\/viewcontent.cgi?article=1730&amp;context=extension_histall\" target=\"_blank\" rel=\"noreferrer noopener\">Deicing Compounds and Utah Landscapes (opens in new window)<\/a>. <em>Utah State University Extension Publication<\/em> HG-511. Utah State University.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Richard T. Koenig, Professor of Soil Science, Department of Crop and Soil Sciences, Washington State University Paul R. Grossl, Department of Plants, Soils and Climate, Utah State University, Logan Urban Soils Soils in urban settings are subjected to a myriad of physical, chemical, and biological disturbances and processes that are fundamentally different than those in [&hellip;]<\/p>\n","protected":false},"author":241,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"_wsuwp_accessibility_report":null},"categories":[],"tags":[],"_links":{"self":[{"href":"https:\/\/extension.wsu.edu\/pnw-gardeners-handbook\/wp-json\/wp\/v2\/pages\/735"}],"collection":[{"href":"https:\/\/extension.wsu.edu\/pnw-gardeners-handbook\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/extension.wsu.edu\/pnw-gardeners-handbook\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/extension.wsu.edu\/pnw-gardeners-handbook\/wp-json\/wp\/v2\/users\/241"}],"replies":[{"embeddable":true,"href":"https:\/\/extension.wsu.edu\/pnw-gardeners-handbook\/wp-json\/wp\/v2\/comments?post=735"}],"version-history":[{"count":54,"href":"https:\/\/extension.wsu.edu\/pnw-gardeners-handbook\/wp-json\/wp\/v2\/pages\/735\/revisions"}],"predecessor-version":[{"id":4878,"href":"https:\/\/extension.wsu.edu\/pnw-gardeners-handbook\/wp-json\/wp\/v2\/pages\/735\/revisions\/4878"}],"wp:attachment":[{"href":"https:\/\/extension.wsu.edu\/pnw-gardeners-handbook\/wp-json\/wp\/v2\/media?parent=735"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/extension.wsu.edu\/pnw-gardeners-handbook\/wp-json\/wp\/v2\/categories?post=735"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/extension.wsu.edu\/pnw-gardeners-handbook\/wp-json\/wp\/v2\/tags?post=735"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}