Composting and Compost Use (APSC 2003)

Module 1 of the "Composting and Compost Use" course provides students with a basic understanding of compost and composting, and teaches them how the principles of composting are applied when combining various organic feedstock materials.

The primary focus in Module 1 will be on getting a composting system established. During this module, students select, sample and analyse feedstock materials, construct a wire cage composter, formulate a composting recipe, combine materials in the correct proportions, and begin to learn how to monitor, manage and document the composting process. The Operations Manual, provided to all students, outlines the methodology and schedule for completing these composting activities and tasks.

In addition to these composting activities, students learn how to use the on-line discussion forum, and complete the Module 1 assignment, "Developing a composting recipe".

This module provides students with a detailed understanding of what happens during the composting process (i.e., the patterns of microbial metabolic activity and temperature that develop when key composting factors are not limiting), as well as the tools to effectively manage this process until compost is stable enough to be used. Managing the composting process involves maintaining optimum conditions for biological activity until decomposition slows and compost is considered to be reasonably stabilized. Other important process requirements are achieving an acceptable reduction in pathogens and weed seeds, and minimizing losses of nitrogen.

In Module 2, students learn how to:

• Monitor and evaluate the composting process;
• Turn and mix the pile, based on pile temperature and the desired rate of decomposition;
• Maintain moisture content within the optimum range; and
• Troubleshoot common composting problems.

Daily pile temperatures and weekly observations on the composting process are posted to the on-line discussion. At the end of the course, students will prepare a graph of their daily pile temperatures as part of the Module 5 assignment "Documenting and analysing the composting process".

Before the end of Module 2, students complete the assignment, "Evaluating the initial composting mix".

In Module 3, students learn about the on-farm composting of bio-organic wastes which are commonly generated on farms (manure, crop residues, and animal mortalities). Key topics covered in this module are:

• Factors which influence the decision of whether or not to compost on the farm;
• Why composting is a required or recommended practice in organic farming;
• Composting methods and equipment which are appropriate for farm-scale composting; and
• The site and environmental considerations for on-farm composting.

The Module 3 assignment (case study of Lawrence Andres on-farm composting operation) and class discussion (based on the Cornell video "Farm-Based Composting - Manure and More") deepens the students understanding of the diversity of approaches and methods in on-farm composting systems.

Towards the end of Module 3, students look for signs that the composting in their bins is nearing completion. Because of the short time-frame available for composting in this course, the composting objective is to obtain a "reasonably stabilized", rather than mature, compost product.

Once the composting process requirements have been met, it is necessary to evaluate the product to determine its suitability as a soil amendment or horticultural growing medium. A number of organizations have developed standards related to compost quality, and in this module, students learn more about these standards and the tests used to assess the suitability of compost for various end uses or markets for compost.

In the Module 4 assignment, students use some of these tests to evaluate the maturity of their own compost, and determine the extent of decomposition which has occurred in their mix during composting.

Compost quality may be considered a bridge between compost production and compost use, and therefore contains essential elements of both. Compost quality embraces all of the traits which are important in the use of compost (e.g., stability, nutrient content, disease suppressive properties, and pathogen, weed seed, and other contaminant content), and yet these traits are largely determined by the choice of starting feedstocks and the way in which compost is produced. The on-line discussion forum provides students with an opportunity to exchange views and information on these topics, and thereby deepen their understanding of compost quality.

This final module of the "Composting and Compost Use" course teaches students about the considerations and requirements for using compost, as well as factors which are important in the marketing of compost. There are four main reasons for using compost in plant production systems: for soil improvement, for fertilizer, to add humus, and as a horticultural growing medium or mulch.

In Units 1 and 2, students learn about the agronomic considerations for using compost, and how to use compost in the production of field-grown and horticultural crops. Unit 3 focuses on the best uses for compost in organic production. Unit 4 provides students with an introduction to compost markets, and some of the requirements and regulations which are important in the marketing of compost.

In the module assignment, "Documenting and analysing the composting process", students prepare a graph of the temperature of their pile over time, and then evaluate their temperature profile with respect to the efficiency of the composting process and stability of the final product.