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Using Compost in Green Infrastructure and Land Management

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Using Compost in Green Infrastructure and Land Management

Not just for Plant Establishment anymore, Compost is also used for Erosion Control, Storm Water Management and Green Infrastructure

The recycling of organic 'wastes' is one of our nation’s greatest assets, and we can utilize these products to address several of societies vexing challenges. The commercialization of composting as an economic method to manage organic (carbon-based) ‘wastes’, got its rebirth in the late 1970’s and has grown from coast to coast; with over 4,500 larger-scale facilities in operation. Over 400 public and private composting facilities exist in Pennsylvania and Delaware, and they are of various shapes and sizes. These facilities manufacture a unique soil amending product – ‘compost’ - which can be used in a multitude of landscaping and land management applications (figure 1), and which provide many benefits (figure 2). Over the past 35 years, compost has become a staple of the landscaping industry and a ‘fan favorite’ of home gardeners. Compost is also popular in many other applications; including turf establishment and maintenance, agricultural production, and more recently, erosion control. Compost has the unique ability to improve the physical, chemical and biological characteristics of soil, creating "Healthy Soils". Healthy Soils have a more symbiotic relationship with plants, and they assist plant health and sustainability by:

  • Reducing soil compaction in heavy soils,
  • Improving moisture holding capacity and availability,
  • Providing some nutrients (for both the plants and the soil microbes), and
  • Supplying stabilized carbon, which is food for soil microbes.

Some of these soil microbes work symbiotically with plant roots, helping them better absorb nutrients and water, while others offer natural disease suppression. But there’s much more to the story, as compost can be used in more sustainable or 'green' construction practices, and in soil and water management techniques that are often less expensive and more effective than current techniques.

Following this introductory article, we will provide articles outlining the use of compost in typical landscape applications, then erosion control and storm water management, and ‘low impact development (LID) and green infrastructure type applications (e.g., component to green roof, bioretention, bioswale media, etc.). Also, the effective specification and purchase of compost will be discussed.

Interestingly, aside from helping plants establish and grow, most of the applications mentioned above provide important environmental benefits related to water and soil protection and conservation, as well as storm water management. In fact, creating more porous landscape soils using compost is used as a storm water management technique in some states (e.g., Virginia), while compost is often required as a main ingredient in bioretention soils used in the Mid-Atlantic States. The importance of mentioning these technical benefits is that with a changing climate, the general public will end up incurring greater costs related to managing the effects of both more frequent and severe droughts, as well as extreme storm events (e.g., flooding). Although we are not suggesting that the use of compost in the applications outlined above will mitigate the effects of these devastating events (and/or inadequate infrastructure), we can emphatically state that we can lessen their effects. This can be done in both an economic and environmental manner – while adding more carbon to the soil, slowing the effects of climate change - reducing the urban heat island effect, and providing benefit in an aesthetically pleasing way.

These discussions illustrate the importance of developing dual purpose landscapes, ones which are both attractive and which provide environmental functionality. Further, they point out the importance of the landscape industry offering these forward minded services to the marketplace.  

We hope that you will read the upcoming articles.



Mr. Alexander has over 30 years of experience working with compost and other organic recycled products on large-scale construction projects, and is a member of the ASLA. He began his career in Philadelphia, and is now the President of R. Alexander Associates, Inc., a consulting company specializing in product development for organic recycled products. He is the author of the ‘Field Guide to Compost Use’, American Association of State Highway and Transportation Officials' Erosion Control Specifications for Compost, and 'Landscape Architecture Specifications for Compost Utilization'.

He provides technical assistance to Laurel Valley Soils, a large composter in Avondale (http://laurelvalleysoils.com/). Contact Ron Alexander at alexassoc@earthlink.net or 919-367-8350 if you are interested in additional information on compost use or a related Lunch & Learn.

Figure 1 – Compost Applications

     Soil Incorporation

  • Turf establishment
  • Garden bed preparation
  • Reclamation/remediation
  • Nursery production
  • Roadside Vegetation

Surface Applied

  • Garden bed mulch
  • Erosion control media
  • Turf topdressing

      Growing Media Component

  • Container/potting substrates
  • Landscape (e.g. rooftop, raised planters)
  • Backfill mixes (tree and shrub plantings)
  • Golf course (e.g. tee, green, divot mixes)
  • Manufactured topsoil
  • Storm water management (e.g., bioretention, rain garden, rooftop garden, bioswales)

Figure 2 – Compost Benefits

  • Improves soil structure and porosity – creating a better plant root environment;
  • Increases moisture infiltration and permeability, and reduces bulk density of heavy soils – improving water infiltration rates and reducing erosion and runoff;
  • Improves the moisture holding capacity of light soils – reducing water loss and nutrient leaching, and improving moisture retention;
  • Improves the cation exchange capacity (CEC) of soils;
  • Supplies organic matter;
  • Aids the proliferation of soil microorganisms;
  • Supplies beneficial microorganisms to soils and growing media;
  • Encourages vigorous root growth;
  • Allows plants to more effectively utilize nutrients, while reducing nutrient loss by leaching;
  • Enables soils to retain nutrients longer;
  • Contains humus – assisting in soil aggregation and making nutrients more available for plant uptake;
  • Buffers soil pH;
  • Supplies essential plant nutrients. 

Developed by R. Alexander Associates, Inc. for the US Composting Council

The Food and Agriculture Organization of the United Nations defines "Soil health" the capacity of soil to function as a living system. Healthy soils maintain a diverse community of soil organisms that help to control plant disease, insect and weed pests, form beneficial symbiotic associations with plant roots, recycle essential plant nutrients, improve soil structure with positive effects for soil water and nutrient holding capacity, and ultimately improve crop production. A healthy soil also contributes to mitigating climate change by maintaining or increasing its carbon content.

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