Wednesday, 9 November 2005
19

Agricultural Management Affects Soil Nematode Communities in a Continental Climate with Cold Winters.

Mario Tenuta, Department of Soil Science, University of Manitoba, 362 Ellis Bldg., Winnipeg, MB R3T2N2, Canada, Martin H. Entz, University of Manitoba, Dept. of Plant Sci. Fort Garry, Winnipeg, MB R3T 2N2, Canada, and Karl M. Volkmar, Agriculture and Agri-food Canada, Brandon, MB R7A 5Y3, Canada.

We assessed the response of soil nematode communities to agricultural management practices in Manitoba Canada (continental moist mid-latitude climate with cold winters. In summer 2003 three sites from southern Manitoba covering a range of management intensities were sampled: a loamy sand having impoverished prairie, pasture prairie, and potato-cereal fields; a clay soil in its 13th year as restored prairie (previously in cereal cultivation) and 13th year flax phase of three, four-year rotations managed conventionally or organically (without fertilizer and herbicide); a silt loam soil in its 6th year potato phase of five rotations. Nematode trophic groups indicated soil food webs of the restored and pastured prairie to be dominated by herbivores (Tylenchus, Helicotylenchus) and bacterivores (Plectus, Acrobeles), potato soil by bacterivores (Rhabditidae) and fungivores (Aphelenchus), and the flax soil by bacterivores (Eucephalobus), herbivores (Filenchus) and fungivores (Aphelenchus). Poor plant productivity of the impoverished prairie was reflected in low total nematode counts and reduced presence of herbivores. Other taxa were associated with particular management, Helicotylenchus where wheat grown and Xiphinema in potato-wheat-canola-wheat rotation. Thirteen years of management as restored prairie altered dominance of the nematode community to several taxa of the Tylenchidae and to Eudorylaimus. The Nematode Enrichment Index values of the pasture prairie and impoverished prairie were lower than other treatments (about 0.50 compared to >0.70). The Nematode Structure Index decreased with management intensity ranging from about 0.75 for the prairie soils (lowest management intensity) to 0.15 for potato soils (highest management intensity). This trend was also evident for management intensity of the flax rotation, Nematode Structure Index values were higher for organic (0.48) than conventional (0.35) management. For continental climates with cold winters analysis of nematode communities can be a valuable means of describing the effects of management on the structure of soil food webs and their functioning.

Back to Management and Soil Biology
Back to S03 Soil Biology & Biochemistry

Back to The ASA-CSSA-SSSA International Annual Meetings (November 6-10, 2005)