2007 Annual Report 1a.Objectives (from AD-416) Improve soil structure and reduce soil strength to improve crop productivity and environmental quality. Improve Coastal Plain soil physical properties that increase infiltration of rainfall/irrigation and increase plant available water content using conservation tillage and reduced compaction. Develop structure in sandy Coastal Plain soils to increase plant-available water holding capacities, reduce penetration resistance, sequester carbon, and bind excess phosphorous and trace elements. Increase soil organic matter contents to improve soil physical/chemical properties in highly-weathered sandy Coastal Plain soils using cover crops and green manures. 1b.Approach (from AD-416) Three avenues will be explored to understand soil mechanisms and develop new management systems that enhance Coastal Plain soils for increased production and improved environmental quality. First, soil amendments will be assessed for their ability to increase aggregation and organic matter contents in Coastal Plain soils; this can lead to more effective water holding capacities for plant use, improved infiltration, and reduced compaction. Soil amendments, such as environmentally friendly versions of polyacrylamide, water treatment residuals, and organic matter, will be analyzed in laboratory experiments to determine their potential to improve soil physical/chemical properties and decrease the need for tillage. Second, cotton and corn growth and yield will be evaluated in treatments that use different deep tillage implements providing various disruption patterns of the subsurface hard soil layer. Treatments for each implement include tillage in the year of measurement and tillage one or two years earlier. Data will be analyzed to evaluate relationships of productivity with soil strength, tillage, and amount/duration of soil disruption by the various implements. Third, carbon sequestration will be evaluated for both above ground (residue) and below ground (root) organic matter additions. Evaluations will take place in twenty plots that have a combination of deep and shallow tillage as well as various crop/cover crop rotations. A mixture of soil, water, and atmospheric sampling techniques will be used to determine the influence of crop management techniques on soil organic matter dynamics. All research is aimed at improving productivity and environmental quality for the benefit of agricultural producers and the general public. 3.Progress Report This research is a major contributor to the multi-location Renewable Energy Assessment Project (REAP; 5440-12210-009-00L). This research is a major contributor to the multi-location Greenhouse gas Reduction through Agricultural Carbon Enhancement network Project (GRACEnet; 5402-11000-008-00L). 4.Accomplishments Carbon evolution from conservation and conventional management: Though large amounts of carbon can be produced in the southeastern Coastal Plain, little remains in the soil. Carbon in the form of CO2 was measured as it dissipated from the soil surface of treatments that had been either surface tilled or not surface tilled for the past 25 years. More carbon dissipated from tilled plots than from the non-tilled (conservation tillage) plots. Carbon dissipation was related to several soil properties. It was strongly and inversely correlated with water content in the tilled treatments but not in the conservation treatments. As a result, conservation tillage management retained more soil carbon. Conservation tillage can help mitigate atmospheric carbon problems by sequestering it in the soil. The project helps resolve National Program 202: Soil Resource Management; Component: Productive and Sustainable Soil Management Systems; Problem Area 3: Soil Carbon Measurement, Dynamics, and Management. Long-term increase in soil organic carbon using conservation tillage in the southeastern Coastal Plain: Previous research has documented the beneficial effects of using reduced tillage to offset atmospheric CO2. However, there is little information on soil C saturation levels. A long-term tillage study in the Coastal Plain showed that soils were not saturated with C even after 24 years of conservation tillage management; they were still sequestering C. Conservation tillage can be a long-term low-level collector of atmospheric CO2. This information can help global modelers establish C accumulation rates under different crop management practices. The project helps resolve National Program 202: Soil Resource Management; Component: Productive and Sustainable Soil Management Systems; Problem Area 3: Soil Carbon Measurement, Dynamics, and Management. Amendment of soil with PAM to improve physical properties: Sandy southeastern coastal soils contain cemented subsurface hard layers that restrict root development and yield. Hard layers can be softened by adding amendments such as OM and/or PAM. When PAM was added to a coastal soil at a rate of 60 lbs/acre, it increased aggregation, decreased soil bulk density, and decreased the need for water required to maintain soil moisture; but it did not decrease soil hardness. When PAM was added with OM, it showed inconsistent results. More work was needed to determine an effective mix of PAM with OM. However, because PAM increased aggregation and water holding capacities, it has the potential to reduce the need for deep tillage of the hard layer which could save fuel, labor, and equipment. The project helps resolve National Program 202: Soil Resource Management; Component: Soil Conservation and Restoration; Problem Area 9: Remediation of Degraded Soils. Tillage with buried microirrigation tubes: A sandy coastal soil was microirrigated with trickle tubes buried under every row or under alternate mid rows. After 6 years, the soil became so severely compacted that it limited root growth and yield. To alleviate compaction, non-inversion deep tillage was evaluated either in the row or in the mid rows, avoiding the buried tubes. Tillage loosened the soil; but compacted zones remained near the tubes. When tillage was performed in mid rows, it did not improve yield; but when tillage was performed in the rows, it improved cotton yield by 145 lbs/acre. Alternate mid-row tube placement was most effective because it permitted tillage in the row and because a previous study showed it to be more cost effective than placing tubes in every row. The project helps resolve National Program 202: Soil Resource Management; Component: Soil Conservation and Restoration; Problem Area 9: Remediation of Degraded Soils. 5.Significant Activities that Support Special Target Populations None. 6.Technology Transfer Number of web sites managed 1 Number of non-peer reviewed presentations and proceedings 3 Number of newspaper articles and other presentations for non-science audiences 3 Review Publications Bauer, P.J., Frederick, J.R., Novak, J.M., Hunt, P.G. 2006. Soil CO2 flux from a norfolk loamy sand after 25 years of conventional and conservation tillage. Soil & Tillage Research. 90:205-211. Busscher, W.J., Bauer, P.J., Camp, C.R. 2006. Cotton management of a compacted subsurface microirrigated Coastal Plain soil of the southeastern U.S. Soil & Tillage Research. 91(1-2):157-163. Busscher, W.J., Novak, J.M., Caesar, T. 2007. Organic matter and polyacrylamide amendment of Norfolk loamy sand. Soil & Tillage Research 93:171-178. Novak, J.M., Bauer, P.J., Hunt, P.G. 2007. Carbon dynamics under long-term conservation and disk tillage management in a Norfolk loamy sand. Soil Science Society of America Journal 7l(1):453-456.