Long Term Effects of Tillage Intensities on Soil Carbon Dynamics Under Soybean Production Systems of West Tennessee.

Soil organic carbon act as a source and sink for atmospheric CO₂ concentration. Tillage practices and cover crops are well known for affecting total soil organic carbon (TOC) and different carbon (C) fractions, but long-term effect of different intensities of tillage under soybean (Glycine max L.) production systems using wheat (Triticum aestivum L.) as cover crop in southern United States are not well documented. Therefore, this study was conducted to assess long-term impact of different intensities of tillage practices such as moldboard plough (MP), disc plough (DP), chisel plough (CP) and no till (NT) on soil organic C pools under soybean production system. This study was conducted on a 39 years old field experiment in Jackson, TN which has six tillage treatments with four replications. The treatments include MP, DP, CP, NT under soybean, NT with wheat and NT with wheat-soybean double crop. We analyzed TOC as well as different C fractions such as dissolved organic C (DOC), permanganate oxidizable C (POXC) and aggregate protected C (APC) to determine the effects of different intensities of tillage practices on C loss from bulk soil as well as C fractions under soybean production systems. Laboratory analyses are currently underway and the results will be presented at the conference.