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Unit 1: Basic Ecological Concepts and Principles Related to Agricultural Systems

Take-home Message for Agroecosystem Managers

Like all ecosystems, agroecosystems are dependent on the continuous flow and cycling of energy and nutrients. As energy is transferred from one organism to another, much of it is lost to heat. And in agricultural systems, the final transfer of energy in the form of a marketable product leads out of the system entirely. Compounding this inherent inefficiency, additional energy inputs (e.g., fuel, nutrients, electricity, etc…) are required in order to grow, harvest, process and market the end product. So an important task for agroecosystem managers is to try and manage the energy and nutrient cycles to be as efficient as possible. In this context, sustainability goals might include reducing the quantity of purchased fertilizer applied to the field; or if fertilizer has to be applied, making sure that most of those nutrients are taken up by the crop and not lost to the soil. Likewise, farmers and ranchers are increasingly looking for ways to improve the energy balance within their systems, both for environmental and profit reasons. The complexity of agricultural systems, with energy and nutrient cycles interacting and connecting at various points, makes this a challenge.

Here are some key sustainable agriculture practices related to this principle that we will be exploring in Unit 2:

• Cover crops

• Minimum/reduced tillage

• Compost and other soil amendments