Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 4/9/1999
Publication Date: N/A
Technical Abstract: Soil disturbances associated with crop production may lead to a deterioration of several aspects of soil quality, with increasing risk of soil loss due to wind and water erosion. A field study was conducted within a long-term experiment with no-till and chisel till practices and an input of residues of 3 t straw per hectare per year. Further, the effect of leaving straw at the soil surface was examined. A range of microbial parameters, soil and air temperature and soil moisture was monitored across a growth season of spring wheat. The observed effects of tillage practice were small relative to effects of leaving a layer of residues at the soil surface. Higher concentrations of plant available N and P were observed in plots with a residue cover in the early spring, possibly due to reduced leaching losses and leaching of nutrients from the straw. Temperature fluctuations were dampened in soil covered by a layer of residues at 5 cm depth. Changes in the composition of the microbial biomass, as described by substrate utilization potentials, phospholipid fatty acid profiles and whole-soil FAME profiles, were limited. Qualitative changes in PLFA composition were more pronounced at 5-15 cm depth than at 0-5 cm depth, but when analyzed quantitatively the shifts in PLFA composition in both depth intervals were of similar magnitude. The amounts of lipid material extracted by the whole-soil FAME procedure was quantified and compared to the yields obtained by the more specific PLFA analysis. Several pieces of evidence suggested that the whole-soil FAME analysis includes a significant background of material derived from soil organic matter.