Wood chips and mulch as a product: what extension services and waste agencies say

This page reports what the named codes, regulators and makers say. It is not training and does not teach the work. This page reports what the official source says. It is not legal advice: ask the office named here. The exemption described below applies in England only and the EPA figures are national statistics, not a rule. How mulch is laid around a tree is on the mulch depth page. Moving chips and wood under pest quarantines is on the moving wood guide, and the rules for disposing of tree waste in England are on the England tree waste guide.

What arborist chips are, as extension describes them

Washington State University Extension (fact sheet FS160E, copyright 2015, by Linda Chalker-Scott) says arborist wood chips include bark, wood and often leaves, unlike the uniform texture of sawdust and bark mulches. It says this mix resists the compaction often found in sawdust and bark mulches, and that in many urban areas arborist chips are available free of charge. It calls wood chips slow decomposers that supply nutrients slowly and soak up water that they release slowly to the soil. It also says the research it cites ranks wood chips among the best performers for moisture retention, temperature moderation and weed control.

Where the extension sources differ

Question	Washington State, FS160E	Oregon State and Georgia
Do chips tie up nitrogen?	No: over time woody mulch raises nutrient levels in soil or foliage, though there is a nitrogen shortage at the boundary between mulch and soil, which it says probably holds back weed seed germination	Oregon State says chips can tie up nutrients, especially nitrogen, more so for small particles such as sawdust and when mixed into soil than when left on top. Georgia says fresh chips in contact with soil can cause a loss of nitrogen, and suggests stacking fresh chips to weather for months or a year
Fresh or aged?	Fresh chips, unless there are concerns about disease, because some of the nitrogen from leaves and needles is lost in composting	Georgia: aged for months or up to a year before use as mulch
Chips from diseased trees	Most studies indicate diseased mulch cannot transmit pathogens to the roots of healthy trees; it says wood mulch is not worked into the soil as an amendment, which raises the chance of disease transfer	Not covered
Acid soil, termites, fire	Says wood chips do not acidify soil in field conditions, are not attractive to termites, and are the least flammable of the organic mulches, with rubber mulch the most hazardous of all it names	Not covered
Use on paths	Not covered	Oregon State recommends chips as a mulch on paths and on the surface around plants, with worms incorporating them over time

The Oregon State page was published in May 2013 and reviewed in 2024. The Georgia piece is dated February 18, 2010 and quotes a county extension coordinator.

Chipped wood as waste: England

The Environment Agency's page on the T6 waste exemption (published April 28, 2014, last updated July 21, 2025) applies to England. It says the exemption allows chipping, shredding, pulverising or cutting waste wood and plant matter to make it suitable for products such as mulch, panel board, fuel and surfacing for tracks and paths. It says virgin wood, meaning trees and branches from forestry work or the management of land, gardens and parks, is not classed as waste, and that no T6 is needed to chip virgin wood. It also says no T6 is needed for shredding twigs and leaves from tree surgery if they are left in place to benefit the ecosystem or shredded for transport elsewhere.

The same page lists activities that need a T6, among them chipping untreated waste wood for boiler fuel, cutting waste wood to size for chipboard, and bringing in waste wood and plant matter from another site. It says chemically treated waste wood, meaning wood that has been preserved, varnished, coated, painted or exposed to chemicals, cannot be shredded to make animal bedding or compost. For the exemption it gives limits of 500 tonnes treated or stored in any 7-day period and storage for up to 3 months after treatment. It places the exemption in charging band 1 and says there is a charge for most waste exemptions.

Chipped wood as waste: United States

The US EPA's wood page (updated March 19, 2026) reports 2018 figures for municipal solid waste. Wood generated was 18.1 million tons, 6.2 percent of the total. Pallet recycling, which EPA says is usually chipping for uses such as mulch or bedding and excludes wood burned as fuel, was 3.1 million tons, a 17.1 percent recycling rate. Wood landfilled was 12.2 million tons. EPA says pallets account for over 90 percent of wood packaging. Those figures cover municipal waste, not tree service debris as such, which the EPA page does not break out.