Return to the Carbon Cycle

Turf Grass Production and Stewardship

1. Turf grass is generally grown within a monoculture system, and as such, has a delicately balanced ecosystem.

2. All too often, lawns have way too much phosphorus (P) and potassium (K), and not nearly enough nitrogen (N).

3. Carbon-depleted soils cannot effectively hold nitrogen for the length of time it takes roots to absorb it; thus, it runs off, dissolved in water, or floats off in the wind as it gasifies.

4. Fertilizer programs worsen soil conditions because they do not put back carbon, which feed microorganisms and keeps soil fluffy and gas-permeable. Soils that are fluffy are said to have loft. Soils that have loft are said to be gas-permeable. Gas-permeable simply means that soils have an air exchange rate between the atmosphere and the soil that is great enough to sustain microbial life below the surface.

5. How well a soil breathes, i.e., how deeply and how thoroughly, is a function of how much and what types of carbon are present.

Types of Carbon Present in Healthy Soils

1. Sugars created by plants through photosynthesis and exuded through their roots feed the microbial life colonizing the roots of the same plant. These are the “heart-pounding, thrill-a-minute, makes-life-worth-living” forms of carbon that sustain the relationship between plants and the beneficial microbes on their roots.

2. Carbohydrates, starches, and cellulose, which come from plants or parts of plants that have died and fallen into the soil, are more complex and enduring forms of carbon that not only serve as food for the soil food web, but also provide structure.

3. Polysaccharides and lignins, the most durable of all the carbon structures, along with other features of the soil, form the foundation for “soil horizons.”

4. These soil horizons represent different “divisions of labor,”  organizing themselves into different horizontal layers.

5. All the forms of carbon within the soil layers serve multiple functions:

* They provide loft so that soil breathes and microorganisms get oxygen.
* They attract, absorb, and hold water for plants and microorganisms.
* They attract, absorb, provide, and disperse minerals and nutrients for microorganisms and plants.
* They provide surface area and structure for microbial activity and plant root development.

6. The life of the soil is dependent on these four factors:
* Oxygen
* Water
* Food-sugars, carbohydrates, amino acids, and other raw materials
* Structure and shelter

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