Chapter 10

Compost Management on Organic Farms

Benefits and Limitations of Compost

Compost has been considered as a valuable soil amendment for centuries. Organic farmers are aware that using composts is an effective way to increase healthy plant production, reduce the reliance of chemical fertilizers, and conserve natural resources. Compost provides a stable organic matter that improves the physical, chemical, and biological properties of soils, thereby enhancing soil quality and crop production. Limitations of composting by-products are cost for site preparation and equipment, the lengthy treatment period, targeting final use of compost product, and environmental issues such as odors, and dust. Some investment in equipment and site preparation is required or recommended. Composting is not a rapid stabilization process and, depending upon technique, could take several weeks to achieve stable compost.

Benefits and Limitations of Compost

Improved Manure Handling

Composting reduces the weight and volume of the manure bedding mix, primarily as a result of reducing its moisture content by approximately 30 to 50 percent.

Reduced Odor Nuisance

While some odors are given off during the composting process, these are generally released during pile formation and initial turnings.

Improved Soil Structure

Compost can greatly enhance the physical structure of soil. In fine-textured (clay, clay loam) soils, the addition of compost will reduce bulk density, improve friability (workability) and porosity, and increase its gas and water permeability, thus reducing erosion. When used in sufficient quantities, the addition of compost has both an immediate and long-term positive impact on soil structure.

Improved Soil Moisture Management

The addition of compost may provide greater drought resistance and more efficient water utilization.

Modifies and Stabilizes Soil pH

Compost can also buffer soil acidity or alkalinity so as to develop a more optimal pH for plant growth. Depending on the pH of the compost and of the native soil, compost addition may raise or lower the soil/compost blend’s pH.

Increases Soil Cation Exchange Capacity

Compost will also improve the cation exchange capacity of soils, enabling them to retain nutrients longer.

Provides Plant Nutrients

Compost products contain a considerable variety of macro and micronutrients. Although often seen as a good source of nitrogen, phosphorous, and potassium, compost also contains micronutrients essential for plant growth. Since compost contains relatively stable sources of organic matter, these nutrients are supplied in a slow-release form.

Provides Plant Nutrients

Compost products contain a considerable variety of macro and micronutrients. Although often seen as a good source of nitrogen, phosphorous, and potassium, compost also contains micronutrients essential for plant growth. Since compost contains relatively stable sources of organic matter, these nutrients are supplied in a slow-release form.

Disease Suppression

Compost can suppress plant diseases but not all composts and not all the time.

Limitations in Using Compost

Cost, Management, and Time

Like any other processing operation composting requires equipment, labor, management, and a suitable location. The actual costs incurred vary depending on the type and quantity of equipment needed as well as the amount of work required to develop a suitable site.

Government Regulation

Large-scale composting activities can potentially have negative environmental impacts such as water pollution and the development of significant health nuisances such as odor and the attraction of disease vectors such as rats and flies.

Slow Release of Nutrients

Nutrients in compost are generally in an organic form, which needs to be mineralized in the soil prior to becoming available to plants.

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