Soil carbon stock at any one time reflects the balance between the inputs from plant residues and other organic matter, and losses due to decomposition, erosion and leaching. Many things can deplete organic carbon stocks in agricultural soils. Highly productive seasonal growers and plowed fields with intensive cropping systems will lose a considerable amount of organic matter. Some key factors to maximize the effect on soil health include concentration of humic substances, rate, particle size, and biologic activity. The active soil carbon content is generated by the breakdown of humus from applied or grown organic materials.
Perennial crops like trees, fruits, blueberries, and citrus are vulnerable to have long-term effects of poor soil organic matter and active carbon content.
Why should Florida growers be concerned about carbon depletion in their soil?
A healthy soil has a certain amount of soil organic matter that over time produces active carbon content. The active soil carbon content is generated by the breakdown of humus from applied or grown organic materials. If the humus does not exist or the soil is heavily cropped and the active soil carbon is not replaced, there can be great impact on physical, chemical, and biologic properties of the soil. Moisture retention, nutrient retention and leaching is a secondary effect of low carbon. It pays to know your soil carbon content.
How can you tell if your crops are suffering from carbon depletion?
Get a full soil test. With the result of a complete soil test you can look for low cation exchange capacity (CEC). In addition, low soil organic matter is an indicator of carbon depletion. Phoslab Environmental Service helps Florida growers by providing soil testing.
There are ways to decrease carbon depletion
Conversion of plowed fields to pasture has the potential to reverse the depletion process, recapturing organic matter that was lost under more intensive cropping systems. Although good management practices following conversion to pastures can increase soil carbon sequestration, land managers must realize that limits exist to the amount of carbon that can be stored. Mature pastures and those that are heavily utilized, either by haying or grazing, can not be counted on to continuously accumulate soil carbon.
Resources About Carbon Depletion
- Could Carbon Farming Save Our Soils – http://www.mnn.com/your-home/organic-farming-gardening/stories/could-carbon-farming-save-our-soils