Article by Reza KhosraviPhotos by Jeff Geerts

THE DIRT ON

Many communities in America are faced with a garbagedisposal problem. Iowa is no exception with fewer landfills,adverse public sentiment, preferred uses for land and pastproblems associated with older landfills such as contaminationof groundwater.

To ease these worries and to make waste managementwork better, Iowa, like many other states, has adopted anintegrated approach to waste management. The 1987 GeneralAssembly established a statewide solid waste management

.~. policy as part of the Groundwater Protection Act. The actidentifies a hierarchy of preferred management options in thisorder - waste reduction at the source, recycling and reuse,combustion with energy recovery, combustion for volumereduction without energy recovery, and landfill disposal. In1989 the Waste Reduction/Recycling Act set a statewide wastevolume reduction goal of 25 percent by 1994 and 50 percent by2000, with July 1, 1988, as the baseline year.

While no single method will provide a panacea to ourcurrent solid waste problems, the potential to reduce the wastestream by diverting yard waste led Iowa to pass legislationbanning the disposal of yard waste effective January 1991.Yard waste accounts for 17 to 18 percent of the municipalsolid waste stream. Banning yard waste from landfilling plusreducing the cost between landfilling and compo sting hasmade composting a viable alternative. In addition, the factthat composting is a "natural process" has helped foster itspopularity.

In the U.S. composting has been used for years to stabilizesewage sludge, industrial waste and municipal solid waste(MSW). Organic materials make up 70 to 80 percent of theMSW stream. Yard wastes, which are included in thatcategory, may contain even larger proportions of organicmaterials. Certain industrial wastes, such as those from thefood processing, agricultural and paper industries, are mostly

organic in composition. Because of their large proportion oforganic materials, yard wastes are ideal candidates for wastereduction by composting.

Why compost?Composting at home can reduce personal trash volume,conserve water, increase plant growth and replace the need forchemical fertilizers. Moreover, with the accelerated rate oftopsoil erosion, we can no longer afford to send valuableorganic materials to landfills when we can use them toimprove soil structure, texture and increase its water-holdingcapacity.

How to compost?Composting is a controlled biological decomposition oforganic matter. It is a natural way of returning nutrients andhumus to the soil through the action of microorganisms. Ifyou have ever walked through a forest, no doubt you havenoticed the process of decomposition. The top layers underyour feet are recognizable as leaves and twigs but the layersbelow have been transformed into rich soil. Decompositionhas been happening for millions of years proving that friendlymicroorganisms naturally like to eat grass, leaves and foodscraps. Remember, what has been going on for millions ofyears in the forests and woods can go on naturally in yourbackyard if you decide to compost. Compost can be madeeither in bins or open piles. However, bins will keep pilesneat, while retaining heat and moisture and are probably moresuited to urban areas with less space to spare. Whatever yourchoice, certain environmental conditions must be met in thecompost pile.

Microorganisms are the key elements of the decompositionprocess. They are the liberators of the nutrients which makethe plants grow. There are two separate families of microor-

The fact that composting is a "natural process" has helped foster its popularity.

Composting at home can reduce personal trash, conserve water, increase plant

The heat generated within the composting pile due tothe activities of microorganisms is important for maximumdecomposition and production of safe compost. Most danger-ous microbes are inactivated effectively at temperatures above130 degrees F. Normally there is no need to add external heatsince microorganisms generate heat in the process of dycom-position.

The balance of brown (carbon) and green (nitrogen)materials is essential to a healthy compost pile as well. Byhaving a balance of wet, green materials (grass clippings,food scraps, manure) and dry, brown materials (dry leavesand woody materials), compost piles generate high tempera-tures and slowly simmer to create compost. Using only brownmaterials in the pile will slow down the composting processbecause piles do not generate sufficient heat. By adding onlywet, green materials without dry, brown materials, odors maydevelop. The microorganisms in the piles are like plants.

They have more orless similarnutritional needs ashigher plants(nitrogen. assupplied by greengrass or manuresadded to the pile;phosphorous,

potassium and other trace elements as supplied by eithergreen or brown materials added). One major differencebetween microorganisms in compost and plants is thatmicroorganisms rely on the brown (carbon) organic matter fortheir energy source, as opposed to the photosynthesis processfor higher plants.

While backyard composting is agood alternative for many of us,many other residents elect tobag their yard waste for curb-side pickup to large municipalor regional composting sites.

How long does it take to produce compost?The composting process can take as little as one month or aslong as two years, depending on the environmental factorsdiscussed. However, when it is ready, you will have acompost which is dark brown or black and crumbly - humus-rich topsoil with a sweet aroma of a good earth. Foul odorsonly occur where there is a lack of oxygen or too much wet,green material and too little brown, dry material. Alleviatethe bad odor by turning the pile or poking the pile and mixinggreen and brown materials together.

While backyard composting is a good alternative formany of us, many other residents elect to bag their yard wastefor curbside pickup to large municipal or regional compostingsites. Organic Technologies is one of many successful large-scale composting operations in Iowa (see article at left).

Reza Khosravi is an environmental specialist for the WasteManagement Assistance Division in Des Moines.

growth and replace the need for fertilizers. Because of their large proportion of

ganisms distinguished by the presence or lack of oxygen in theirlifecycle. Aerobic microorganisms are busy working in yourcompost pile when the pile is in open well-circulated air.Anaerobic microorganisms are the ones that are active underthe condition of no oxygen. But amazingly both groups arespecialized to do the job and break down the twigs and theleaves.

Oxygen is another important factor in the decompositionprocess. As mentioned before, aerobic microorganisms needplenty of air to be active. When there is enough air in the

compost pile, thesebacteria do the jobright and decompo-sition goes at a muchfaster rate. A 5- to15-percent oxygenconcentration isconsidered adequate.Unless speed is yourpriority, frequent

turning is not necessary. The purpose of turning is to let airget into the pile and increase the oxygen flow. There areseveral other ways to increase oxygen. Experiencedcompostors often place branches on the bottom of their piles toincrease the air flow. Another easy way to introduce air is touse a rod or pitchfork and simply poke several deep holes intothe heart of the pile.

Water is needed for both aerobic and anaerobic microor-ganisms. It is naturally added to the compost pile during theprocess of decomposition. Remember that maintaining anadequate moisture level will create a friendly home for themicroorganisms, earthworms and insects. The pile should beabout as wet as a squeezed-out sponge. Sprinkling water onthe pile will keep it moist and covering the pile with a tarp will

. . . if you have ever walkedthrough a forest, no doubt youhave noticed the process of de-composition.... What has beengoing on for millions of years inthe forests and woods can go onnaturally in your backyard ...

••At Organic Technologies Corp. lIlearVan Meter a windrowturner (top photo) is used to stilrthe compost pile tocirculate more air into the piles ..

The Brown Bear Model PA 35 is ideally suited for small tomedium sized composting oper,i\tions. Shown here mountedon a Ford bi-directional tractor, the PA35 can be mounted toany 85-125 HPfarm tractor equilpped with a Category II or III3 point hitch and 540 RPMPrO (bottom photo).avoid the loss of moisture. An overly wet pile is as bad as adry pile, so excessive moisture should be avoided. Excessivemoisture creates an anaerobic condition which results in thedevelopment of odors in the compost pile and can also delaythe decomposition of materials.

organic materials, yard wastes are ideal candidates for waste reduction by compostin .