Submitted to: Southern Conservation Tillage for Sustainable Agriculture Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 6/24/2002
Publication Date: 6/24/2002
Citation: Runion, G.B., Prior, S.A., Reeves, D.W., Rogers, H.H., Reicosky, D.C., and White, D.C. 2002. Microbial responses to wheel-traffic in conventional and no-tillage systems. In Santen, E. van (ed). Making conservation tillage conventional: Building a future on 25 years of Research, Proc. of 25th Southern Conservation Tillage Conference for Sustainable Agriculture. pp. 227-232. Special Report No.1. Alabama Agric. Expt. Stn., Auburn University, AL. Interpretive Summary: Traffic-induced soil compaction and tillage systems can impact the productivity and sustainability of agricultural soils. Our goal was to assess the response of soil microbes (bacteria and fungi) to wheel-traffic in two tillage systems on a coarse textured soil. Traffic had little effect on total nitrogen found in microbial bodies. Traffic increased activity of microbes only in no-till plots, likely due to more crop residue which provided more favorable soil moisture conditions. The largest differences in response of microbes was between the conventional tillage and the no-till cropping systems; soil water, microbial biomass N, and microbial activity were all higher in the no-till system. Our findings suggest that conventional tillage practices result in a lower level of soil microbes which are older and change less over time while the community under no-tillage is a younger, more actively growing population. Overall, response of microbes indicate that soil quality is improved by using no-till farming practices.
Technical Abstract: Traffic-induced soil compaction and tillage systems can impact the productivity and sustainability of agricultural soils. The objective of this study was to assess the response of soil microbial populations to wheel-traffic in two tillage systems on a Norfolk loamy sand (Typic Kandiudults; FAO classification Luxic Ferralsols). Experimental variables were with and without traffic under conventional tillage (disk harrow twice, chisel plow, field cultivator-planter) vs. no-tillage employed in a split-plot design with four replications; main plots were traffic and subplots were tillage. Soil samples were collected from 0-2 and 2-4 cm depths, sieved (2 mm) and used to assess soil water content, microbial biomass nitrogen (N), dehydrogenase, and microbial characterization using phospholipid ester-linked fatty acid (PLFA) analysis. Traffic increased soil water content, had little effect on microbial biomass N, and increased microbial activity (no-till plots only) likely due to increased amounts of residue. Soil water content, microbial biomass N, PLFA estimates of microbial biomass, and microbial activity were all consistently higher in no-till compared to conventional tillage plots. Data from this study suggest that conventional tillage results in a lower, more static, possibly more mature community of microbes while the microbial community under no-till appears to be a younger, more viable growing population. Finally, these data suggest that overall soil quality, at least in the surface soil layer, is improved in agricultural systems employing no-till operations.