BioCycle Magazine

State Fertilizer Officials Focus on Compost


Courtesy of BioCycle Magazine

For two years, the U.S. Composting Council’s (USCC) marketing committee has been meeting with the American Association of Plant Food Control Officials (AAPFCO) to discuss how the two organizations could work together to create a uniform compost bill to be given to each state legislature to consider adopting into law. AAPFCO is an organization of fertilizer control officials from each state in the U.S. (as well as representatives from Canada and Puerto Rico) who are actively engaged in the administration of fertilizer laws and regulations. These officials cover the regulation of fertilizer, soil amendments, agricultural liming materials, chemigation (irrigation systems used to apply fertilizers) and agricultural anhydrous ammonia. AAPFCO has model bills it provides to state legislatures as well as specific rules on fertilizer labeling and storage.

A uniform compost bill would allow compost products to be registered in several states without confusion, assuming the bill was adopted into law via legislation. For those who bag compost and other organic products, the registration, labeling and regulatory aspects of conducting interstate trade can be difficult. The thought of having 50 states with 50 different methods of viewing acceptable compost was a stimulus for the meetings.

Although consistent standards and regulations have been an issue for compost marketers for a long time, the need for cooperation and consensus was heightened in mid-1997 when a fertilizer in Washington state was randomly tested by a suspecting Seattle Times reporter and it was found to contain high levels of some contaminants not normally considered acceptable. (See “Industrial Waste As Fertilizer: What’s Wrong? What’s Right?,” August, 1997.) When this story hit the press, a lot of public concern and confusion began to build over the safety factors associated with inorganic fertilizers. Washington state ended up adopting Canadian standards developed for inorganic fertilizers for all fertilizers — inorganic and organic. Since compost is often considered an organic fertilizer, the USCC got drawn into this discussion about levels of heavy metals allowable in fertilizer products.

As the Washington state issue continued to boil over in the press, AAPFCO felt there was a need to address the concerns about a lack of standards for heavy metals in inorganic fertilizer products. In January, 1998, the group passed a motion to recommend the adoption of the Canadian standards to all state officials and the board of directors approved the motion. Currently, it is up to individual state fertilizer officials to recommend what they feel is appropriate for their state regarding this issue. A decision at the board level is not required to be implemented by all 50 states.

Later in 1998, AAPFCO formed a subcommittee to look at how best to regulate the sale of compost (see “Regulating the Sale of Compost,” October, 1998). One outcome of the subcommittee’s work has been an effort to create a uniform compost bill that will be given to each state legislature to consider adopting into law. The USCC, which has its own initiatives underway to develop national compost product quality standards, has been working with the AAPFCO subcommittee on the uniform compost bill. The current subcommittee involves Teresa Crenshaw, George Latimer, Bill Goodman, Carol Phillips (all from AAPFCO), Vince Snyder (Scotts), Carla Castagnero (AgRecycle), Sharon Barnes (Barnes Nursery and president of the USCC), and Rod Tyler (USCC staff).

What Are The Issues?

From an environmental standpoint, many people feel the nutrients contained in composts are not recognized when compost is used in integrated management programs. For example, landscapers regularly use composts and additional inorganic fertilizers because they often are confused over the issue of whether or not compost adds enough nutrients by itself. The agricultural use of compost encounters the same question, but with increased scrutiny because of nutrient management issues. Many of the committee members felt it was time to begin to recognize the nutritional value in compost so that an integrated system of compost and fertilizer applications can be managed more effectively, regardless of the location of the application.
 Besides these factors, there is a health and safety issue regarding heavy metals. In the Seattle Times story, questions were raised about the safety of inorganic fertilizers and various levels of heavy metals. At that time, the fertilizer industry did not have any standards regarding heavy metal levels. Even though the heavy metal limits in the U.S. Environmental Protection Agency’s Part 503 technical rule for biosolids are considered a standard for many beneficially used residuals other than biosolids, the decision makers in Washington state decided to adopt the Canadian standards for heavy metals in inorganic fertilizers as an interim measure until the Washington Department of Agriculture had enough information to make a rule specific to Washington. The Canadian limits are far lower across all metals than Part 503 and are based on soil background levels rather than a risk based scientific approach.

Scientists have long debated the various factors about risk based, nonrisk based and background levels throughout the struggle to determine just how much of any trace element should be allowed to be used on soils. One important factor that many have missed in their analysis is that the limits in the Part 503 regulations were developed strictly for biosolids products, which behave differently than inorganic products with respect to heavy metals. Dr. Rufus Chaney of the U.S. Department of Agriculture’s Agricultural Research Service in Beltsville, Maryland, continually emphasizes the number of safety factors for biosolids and biosolids compost products in the current 503 limits, which the industry should consider.

However, he is also quick to point out that the 503s do not necessarily apply to inorganic materials because the availability levels of metals like cadmium (Cd) are different. In particular, the Cd in fertilizers is accompanied by only about ten times more zinc (Zn) than Cd, while biosolids contain about 100 to 200 times more Zn than Cd. The Zn inhibits uptake of Cd by plants, and inhibits absorption of Cd by animals which ingest the crops. And, explains Chaney, if poor pH management occurs, plants would suffer Zn phytotoxicity before Cd in the crops would be any problem when biosolids were applied, but not fertilizers. This is especially important for western U.S. phosphate ores which can have very high total Cd levels, up to 400 mg/kg. When biosolids have both enough Zn to prevent risk from Cd, and specific adsorption for Cd added with the biosolids, risks from biosolids-Cd are much smaller than for Cd in phosphate fertilizers.

Chaney adds that the fertilizer Cd limit from Canada allows superphosphate and other high analysis phosphorus fertilizers to contain 171 ppm Cd. And a draft recommendation for fertilizer Cd regulation in California would allow nearly 300 ppm. Comparing these to the 21 ppm maximum Cd recommended for biosolids by USDA (coupled with a strict Cd:Zn limit of <0.015 mass ratio), it seems clear that the 503 rule protections are far more strict than those of the fertilizer rules. It may take longer for the normal application of phosphorus fertilizers to apply enough Cd to cause concerns about food quality, but the Part 503 rule prevents this by Cd:Zn protections.

Where Does This Leave Us?

The chemistry of heavy metal movement and utilization in soils by plants and by animals is a complicated science. USDA has researched the topic for over 20 years and the agency believes that the resulting Part 503s are as good of a science based set of standards for biosolids based products as one can find in the world. The USCC has recommended that AAPFCO consider working with these experienced professional scientists to create a similar risk based approach for inorganic fertilizers and to exempt all composts from the interim Canadian standards for heavy metals. Currently, biosolids are exempt from the Canadian standards.

AAPFCO already has tried to fit compost within current soil amendment and fertilizer laws existing under their organization. However, only about 28 states have a soil amendment law and the use of the interim Canadian fertilizer standards for heavy metals is a decision for each state. The uniform compost bill under development recognizes some of the properties contained in compost. Additionally, discussions about product standards within the bill has begun, which is in parallel to the USCC’s development of compost product quality standards. It is anticipated that the AAPFCO process of uniform bill adoption will take a while because there are many complicated issues. By Rod Tyler and Sharon Barnes.

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