SOIL MITES AND NEMATODES COMMUNITY STRUCTURE IN A CONVENTIONAL AND NO-TILLAGE CHRONOSEQUENCE, COMPARED TO GRASSLANDS
Date
2022-07-29
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
ORCID
0000-0001-6753-3336
Type
Thesis
Degree Level
Masters
Abstract
Understanding the impact of long-term conventional tillage and no-tillage practices on soil biota is useful for estimating the level of disturbance in agroecosystems. An investigation was conducted in a long-term field experiment under no-till and conventional tillage management with a wheat-fallow rotation and in undisturbed grasslands, in the southwestern Canadian Prairies of Saskatchewan, at two different locations: Swift Current and Central Butte. The primary goal of the research was to compare the soil community structure of the nematodes and mites between long-term agro-management regimes and between long-term agro-management regimes and the native prairie land. After over 35 years of conventional tillage practices, both nematode and mite communities were negatively impacted. Thus, the increased soil disturbance (CT, conventional tillage) led to lower diversity and weaker soil nematode community structure than reduced soil disturbance (NT, no-till). The nematode maturity index (MI) revealed a more stable environment in the NT system. Oribatid mites dominated the soil mite community's relative density and genera diversity, regardless of agricultural management. Overall our results showed a positive relationship between crop rotation, reduced soil disturbance, and soil Acari's diversity and maturity in long-term agro-management regimes. Also, long-term agricultural practices (CT, NT) significantly altered the community structures of nematodes and mites compared to those from undisturbed grasslands. Thus, the highest number of identified nematode genera (68) was under native prairie (NP) systems. Nematode diversity and maturity decreased with the intensity of land cultivation. Farming impacted the diversity and community structure of Acari as well. Thus, the highest number of identified mites genera (53) was observed in NP systems, and the most mature community structure was also found in the grasslands. Oribatid mites dominated the soil mite communities in terms of relative density and genera diversity in agricultural land and in terms of diversity in the native prairies. A significantly higher proportion of Prostigmata was observed in grasslands, and a significantly lower proportion of Mesostigmata was attested in the CT system. Overall, the nematode and mites communities analysis affirmed that the tillage system significantly decreased the diversity of nematodes and mites, favoring a weaker organization of their communities. Consequently, their functional metabolic footprint had been severely altered compared to communities in native grasslands.
Description
Keywords
No-tillage, Conventional tillage, Native prairies, Nematoda, Soil mites, Trophic group, Diversity, Community structure.
Citation
Degree
Master of Science (M.Sc.)
Department
Soil Science
Program
Soil Science