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Soil respiration
While improving the chemical and physical properties of soil is important to organic and non-organic agriculture alike, building and maintaining the soil biology is absolutely critical to successful organic farming.
Soil organisms are the building blocks of healthy, productive soils. Like all other living things, soil organisms need food, water and a place to live. Proper organic management creates this sustenance and habitat for both visible soil inhabitants—such as earthworms and insects—and those too small to see—such as beneficial bacteria and fungi (the primary decomposers that support this microscopic ecosystem).
Equally important is the activity in the soil. We call this activity respiration.
When plants die, the insects, worms and microorganisms in the soil begin to break down the plants' carbon and use some of it for food. Through the process of photosynthesis, living plants take in air containing a large percentage of carbon dioxide and convert it to cellulose, starches and sugars in the plant tissue. When these plant residues are incorporated into the soil, the microorganisms use the carbon, cellulose, starches and sugars for their food. Through this same process, other nutrients and micronutrients from the decaying plant tissue are made available for subsequent crops. The "life in the soil" is what makes nutrients available to plants.
Scientists measure soil respiration by determining the amount of carbon dioxide being released. In our Farming Systems Trial, we have found that carbon dioxide respiration is significantly higher in the organic farming systems than in the non-organic system. (Organically managed soils are able to store or sequester the carbon for use by plants as needed.) This means microorganisms are more active and numerous in the organic systems and are recycling more nutrients.
In good organic systems, the soil is working hard for you. Here's what it looks like in equation form: C6H12O6 (carbohydrate in the form of plant material) + O2 (oxygen) = CO2 (carbon dioxide) + H2O (water) + energy (food).
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Click image to enlarge.
Eat or be eaten: The food web is also a food chain with higher soil animals consuming smaller ones for their sustenance. As soil particles are broken down they become more stable, eventually turning into carbon-rich humus. (Image: NRCS Soil Biology Primer)
Researchers use soil respiration chambers, like the one pictured above, to study the relationship between living biomass and dead organic material in forest as well as farming ecosystems.
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