Is Mulch a Decomposer or Producer?

Producers

• Organisms that act as producers, or autotrophs, synthesize their own energy from simple substances present in their environment. Plants are the most familiar example of producers. Through the process of photosynthesis, plants use light energy to break apart molecules of water and carbon dioxide, then put them back together as sugar and oxygen. They use the sugar as food, meaning that plants never have to consume other organisms to obtain energy. Producers make energy from the sun available to other organisms that consume the plants as food and, therefore, serve as the base of the food chain.

Decomposers

• Decomposers are heterotrophs, meaning that -- unlike producers -- they must consume other organisms as a source of food. Decomposers consume dead plant and animal material. This material fuels the energy needs of the decomposers. At the same time, as the decomposers break up organic molecules in order to consume the energy within them, they release nutrients like nitrogen back into the soil, where it becomes available for plants to take up. Without decomposers, nutrients would remain forever tied up in dead plants and animals.

Mulch's Role

• Organic mulches typically come from plant-based sources. Wood chips, bark, straw and grass clippings are all examples of organic materials gardeners often use to mulch their gardens. While these materials were living, they acted as producers, as all plants do. However, since dead plants don't produce energy, once turned into mulch, they no longer play a role as a producer.

  Organic mulches break down over time. Therefore, mulches are subject to the actions of decomposers but do not act as decomposers themselves.

Mulch Benefits

• Even if mulches aren't producers or decomposers, their relationship to both of these types of organisms explains why mulch benefits your garden. Many gardeners use mulch to suppress weeds or preserve moisture in the soil. However, mulch can do much more.

  As once-living plants, mulches contain the nutrients that they absorbed as living plants. As decomposers break down mulches, they release these nutrients back into the soil, where your current plants can reabsorb them. This minimizes the amount of fertilizer your garden requires.

  Mulch also contributes organic matter to your soil. This material feeds beneficial soil microorganisms that, in addition to releasing nutrients into the soil, also crowd out harmful microbes that cause plant diseases. Organic matter also improves soil structure, aeration and drainage.

  Its important to recognize, however, that these benefits come only from plant-based mulches. Natural, inorganic mulches like gravel or synthetic mulches like plastic do not provide nutrients and do not feed decomposing microbes.