Date of Award

1998

Degree Type

Thesis

Degree Name

Bachelor of Science Honours

Faculty

Faculty of Communications, Health and Science

First Advisor

Adrianne Kinnear

Abstract

The practice of broadacre, dryland farming is known to affect the physico-chemical structure of the soil but our knowledge or its impact on the biological structure is rudimentary. The soil acarine (mite) communities which inhabit these soils display a variety of responses to this agricultural practice. With the increasing focus on developing ecologically sustainable agricultural techniques, an understanding of the soil acari becomes increasingly important. This study investigated the impact of two agricultural practices (designated here us Conventional and Non-Conventional) upon the abundance and diversity of the soil acari. Conventional agricultural practice involved broad scale chemical application to weeds and soil and conventional tillage. Non-Conventional agricultural practice involved chemical application to plant foliage only, and minimum tillage by disk ploughing. Comparisons of the soil mite communities were made with the mite communities of an adjacent bushland remnant. Total acarine abundance was highest in the two agricultural sites and was positively correlated with organic matter. However, species richness in these sites was 40% less than that in the Bushland Remnant site. Mites from the Orders Prostigmata and Astigmata were numerically dominant at all three sites. The Non-Conventional und Bushland Remnant sites were most similar when comparing the relative percentage abundance of the orders. Species level analyses revealed that the one species from the prostigmatid family Eupodidae, and one species from the astigmatid family Acaridae, increased in abundance with increasing agricultural disturbance. Both species were positively correlated with total organic carbon. The effect of fertilizer and herbicide application to species abundance is also considered. This study identified differences in mite communities between the Conventional and Non-Conventional agricultural sites, which placed the Non-Conventional site in an intermediate position between the Conventional and Bushland Remnant site.

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