2012 Annual Report
1a.Objectives (from AD-416):
Evaluate the long-term effect of soil organic carbon (SOC) on soil quality: 1)To determine the amount and types of carbon accrued in long-term field plots; 2)To evaluate the effects of tillage practice, winter cover cropping, compost application, soil depth and soil aggregate size fraction on total SOC and SOC constituent contents; 3)To relate total SOC and SOC constituent contents with soil structural stability and erodibility; 4)To determine total SOC content level and constituents most effective at increasing soil stability and reducing soil erodibility; and 5)To identify agronomic practices that effectively increase soil stability and decrease erodibility.
1b.Approach (from AD-416):
Soil quality will be evaluated in university controlled long-term piedmont and coastal field plots that have treatments of no-tillage, no-tillage with winter cover and compost, disk tillage, and disk tillage with winter cover and compost. In each treatment, SOC will be analyzed for particulate carbon, labile carbon, microbial biomass, total soil carbohydrates, and glomalin. SOC components will be related to mineralization, respiration, and aggregate stability. Testing for aggregate stability include wet sieving, dry sieving, and rainfall simulation of selected aggregate sizes analyzing runoff and splash.
This study relates to inhouse project objective 2: Improve degraded soils).
Field plots were maintained under varied tillage, crop rotation, and compost application to show relative degrees of soil quality improvement in sandy coastal plain and clay-enriched piedmont soils. Soil samples were collected for fertility assessment and soil physical properties were measured before and after adoption of these management regimes. Results indicated that soils under no-till combined with a winter cover crop and compost significantly improved soil carbon sequestration, infiltration, fertility, and nutrient retention. Higher crop yields resulted in plots under these three management practices suggesting that producers should consider incorporation into their field management scheme.