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

It is important to note that the different cycles at work in an ecosystem are not self-contained and isolated one from the other. Rather, they interact and are interconnected at various points. This is true in farm and ranch ecosystems as well. Let’s look at how water and carbon are interconnected and how this concept relates to agroecosystem management.

Refer to the carbon and water cycle links from the previous page as you read through the following:

Points of Interaction in the Carbon and Water Cycles

• Carbon’s importance in the water cycle: The organic matter (carbon) in the soil, which comes from crop residue, manure, dead animals and other living matter, can hold about 150 percent of its weight in soil water. The water that is held by the organic matter is not susceptible to percolation and is available for plant uptake during the growing season. The goal in many sustainable agricultural systems is to increase soil organic matter through practices such as reduced tillage and planting of cover crops, which in turn stores water for plants.

• Water’s importance in the carbon cycle: Organic matter decomposition can only take place if there is sufficient moisture. As organic matter decomposes, nutrients are released and become available for plant uptake. As plants grow they also take up water from the soil and release back into the atmosphere through transpiration.