Carbon is an often overlooked, but very important component of the soil. We know how to manage nitrogen, phosphorus and potassium for maximum production, and that micronutrients play a critical role in crop yield and disease resistance. Deficiencies can usually be corrected relatively quickly through the addition of soil or foliar fertilizer applications. While soil nutrient status can change quickly, changes in soil carbon status are generally much slower and effects are less obvious in the short term.
Soil is a living system and has both inherent and dynamic properties — land managers work within the constraints of the inherent properties to change the dynamic properties. Changes in type and amount of soil carbon is one of our biggest opportunities for soil improvement.
Soil health can be defined as the capacity of a soil to function in the areas of biological productivity (i.e. plant growth and decomposition), environmental quality (i.e. water filtration and erosion resistance) and plant and animal health. It is also one of the best indicators of long-term sustainability in land management. The primary unifying factor in all of these areas is soil carbon, the major component of soil organic matter. It is what gives healthy soil its dark brown color and rich, earthy smell.
Soil organic matter encompasses all organic components of the soil system. This includes living and dead plant and animal tissue, as well as excretions and soil microbes. Soil organic matter is typically a small percentage of the soil but has a very important role to play in soil health, disease suppression, drought resistance, water quality and quantity and long-term agricultural viability.
The terms soil organic matter and soil carbon are often used interchangeably, and while one is a component of the other, they are not the same thing. Carbon is the primary component of SOM, accounting for approximately half of the molecular weight. Nitrogen, phosphorus, calcium, magnesium, iron, zinc and other plant nutrients make up the rest. While plants do not take up any significant amount of carbon from the soil (instead they get it from the air), organic matter is the food and energy source for soil bacteria, fungi, worms and the rest of the soil food web. Continue Reading →