Ground Cover Management and Nutrient Source Increase Soil Carbon Sequestration in an Organically Managed Orchard

A common characteristic of weathered, acidic Southeastern US soils is low organic matter content, a condition which can have detrimental effects on orchard productivity. In March 2006 an experimental apple orchard was established to evaluate the effect of three organic nutrient source amendments (untreated control, composted poultry litter, and certified pelletized fertilizer) and four groundcover management treatments (shredded paper, wood chips, municipal green compost, and mow-blow) on tree growth and productivity and soil quality indicators. As a study of the potential environmental impacts of organic orchard management, changes in soil carbon and nitrogen were monitored as affected by the nutrient and ground cover treatments. Soil cores (0–10cm) were collected in 2006 from a Captina silt loam and analyzed for total soil organic matter by loss on ignition. Soil carbon (SC) and soil nitrogen (SN) levels were calculated using known local values of carbon and nitrogen for this soil series. In November 2011 soil cores (0–7.5cm) were collected and directly analyzed for SC and SN by loss on ignition.  SC and SN increased during the period 2006 to 2011 with ground cover and nutrient source treatments with greatest differences observed in the municipal green compost treatments. Increases in SC were positively correlated to increases in SN (P < 0.0001) across treatments. Our results indicate that soil C concentrations can be significantly augmented using organic cultural methods over a relatively short time.