Influence of wheel traffic and tillage on microbial biomass, residue decomposition and extractable nutrients in a Coastal Plain Soil

Abstract

The interactive effects of tillage and compaction from wheel traffic were tested on active bacterial and fungal biomass and organic matter decomposition in the planting row at the surface and within the plow layer of a Norfolk loamy sand (fine-loamy, siliceous, thermic Typic Kandiudult). This experiment was arranged in a split plot design with four replications. Main plots were compaction: 1) compaction from wheel traffic and 2) no compaction from wheel traffic; subplots were tilalge system: 1) conventional tillage and 2) no-tillage. Despite a significant increase in bulk density, compaction from wheel traffic and tillage system had no consistent effects on active bacterial or active fungal biomass either in the top 7.5 cm of soil or in the 15–20 cm depth of soil. Active bacteria and fungal biomass at both depths were usually lower in the winter months than the spring, summer or autumn months. Organic matter decomposition, nutrient mineralization and nutrient availability did not differ among soils that received tillage or compaction from wheel traffic. Organic matter decomposition was greater in all treatments when decomposition bags were buried at 15–20 cm than when they were placed on the surface of the soil. The soil that was sampled was an extremely sandy soil so there was probably not a significant effect of compaction on soil aeration and structure.