Future Trends – Creating Soil Health with Compost
By Ron Alexander
Commercially produced composts are now becoming a staple of the landscaping industry. The most widely available compost products are derived from yard trimmings, biosolids and manure, with both municipal and private composting facilities now producing products in every state. Since landscapers, turf managers and erosion control specialists are struggling with plant loss, increased input costs, and water management issues, compost has been shown to play a vital role in improving both soil and plant health and helping to solve these problems.
Many landscapers have seen that the use of compost has reduced their plant losses on landscape projects, while turf managers and nurserymen alike have seen both accelerated plant growth and a lower occurrence of soil-borne diseases when using compost. However, these are but a few of the many benefits that compost can provide (see Table 1). There are also a variety of uses for compost (Table 2). Compost is primarily used to incorporate into the soil, applied on top of the soil, or as an additive to other soil-like mixes.
The tables above illustrate the versatility of compost, as well as its many agronomic benefits. The fact that compost can improve both low quality soils or subsoils - in which landscapers are often forced to establish their plantings - is the reason why commercially produced compost has become the most popular soil amendment with professional landscapers. Compost is effective in both sand and clay based soils and is produced in every state. Further, the scientific understanding of the benefits of compost use has increased along with the knowledge of how to produce higher quality and more consistent products (see sidebar on National Compost Certification Program and at www.compostingcouncil.org).
Interestingly, compost is also now being seen as the product that can bring health back to soil – improving it chemically, physically and biologically. This is important as the climate changes and growing healthy plants over a sustained period of time is getting more challenging. With more drought and flood occurrences, improving soil quality is a simple way to help assure that plants have a fighting chance to survive. Further, compost has been shown to bind heavy metals and degrade petroleum hydrocarbons found in many soils, thereby improving the environment.
Compost Use
Compost is currently used by landscapers in garden bed preparation and tree/shrub planting projects. Turf managers use it for amending poor soils and nurserymen include compost as a potting media component. There are also a series of newer uses that are changing the way landscapers, turf managers and erosion control specialists are getting the job done – and they are environmentally beneficial. Several of these newer uses are described below.
Topsoil Manufacturing – This is a practice where mineral soil components (e.g., sand, subsoils) are blended with compost in order to create a media that mimics the characteristics of high quality ‘virgin’ topsoil. The compost provides the source of nutrients and organic matter that is missing from the other ingredients. This practice is very popular in many states, and has spawned a new customized soils industry in many regions of the country. This practice is also often completed ‘in-situ’, whereas compost is applied to an area possessing poor soil characteristics and is then incorporated into the soil.
Erosion Control and Storm Water Management – Now that NPDES Phase II regulations are in force, site erosion on landscape and construction projects is being more thoroughly scrutinized. There are many methods used to control erosion and manage storm water, but research over the past 20 years has shown that compost may be the best remedy. Using compost as a soil cover, as a replacement for erosion blankets, or as pyramidal berms instead of synthetic silt fences, has become widespread. National specifications have even been created through the American Association of State Highway and Transportation Officials. Probably the greatest advantages to using compost-based techniques in erosion control are that they:
1) Provide immediate and effective control,
2) Bind and degrade specific chemical contaminants, and
3) Help in the efficient establishment of vegetative (turf) cover.
Green Roof Media - Green roofs have become quite a fad in the landscaping industry and reflective of the growing environmental awareness of architects, builders and city planners in general. Although roof top gardens have long been used for aesthetic reasons, green roofs are now being used in many other countries for primarily environmental purposes. But regardless of the reason, compost has become a popular component of green roof media (providing the organic fraction). Green roofs are typically broken down into two categories: intensive (traditional rooftop gardens) and extensive gardens. Generally, extensive gardens use a more shallow layer of growing media (2”-4”), while intensive gardens use media over 6” in depth. Traditional rooftop gardens are more expensive to construct than are extensive gardens, and usually establish larger plant materials. Extensive gardens often use a lighter weight media and establish specialty plants that are more self-sustaining (e.g., Sedums). Both intensive and extensive gardens are good for reducing storm water runoff (up to 78% was found in a recent North Carolina State University study), but also provide a variety of other benefits. Specifications pertaining to the use of compost on a variety of landscape applications can be found at www.compostingcouncil.org.
Compost is proving to be an important tool to landscapers from coast to coast. It can improve soil health, and therefore, plant health, as well as reduce plant loss and ongoing maintenance costs. Well made, high quality compost can improve not only soil and plant health, but also the environment - and your bottom line! Maybe it’s time for you to try this new old product.
To learn more about compost benefits, applications, and how to use compost in your landscaping and other projects that require improved soil and planting media, join us at the US Composting Council's 17th Annual Conference & Trade Show, January 26-29, 2009 at the Westin Galleria, Houston, TX. The USCC hosts the Largest Conference & Exhibition in North America for the Composting, Wood Waste & Organics Recycling Industry. Attendees participate in the most comprehensive program of training courses, educational & technical sessions, and facility tours & equipment demonstrations. Register at www.compostingcouncil.org
The USCC is a national not-for-profit organization dedicated to the development, expansion and promotion of the composting industry in the U.S.The USCC also directs the Composting Council Research and Education Foundation (CCREF), a charitable foundation, which administers public and private research and education activities. For more information about the composting industry and membership in the USCC, visit www.compostingcouncil.org or call the USCC office at 631.737.4931.
Article by: Ron Alexander
President, R. Alexander Associates, Inc., Apex, North Carolina
Co-Manager, USCC Seal of Testing Assurance Program
Mr. Alexander is a horticulturalist who has been involved in composting and compost use for almost 25 years and is the author of The USCC “Field Guide to Compost Use", the USCC’s "Landscape Architecture Specifications for the Utilization of Compost”, and the AASHTO Erosion Control Specifications.
