The Effects of Glyphosate and Multrazine on the Abundance and Diversity of Soil Microarthropods at the University Park, University of Port-Harcourt, Nigeria

Abstract

The effect of two herbicides, Glyphosate and Multrazine on the abundance and diversity of soil microarthropods (Mites and Collembolans) was assessed in a field experiment conducted from August to December, 2011 at the University of Port Harcourt, Nigeria. The herbicides were applied at varying doses of low (1.4 ml/m2 active ingredient; a.i, standard (2.8 ml/m2 a.i) and high (5.6 ml/m2 a.i) for Glyphosate; and low (2.1 ml/m2 a.i), standard (4.2 ml/m2 a.i) and high (8.4 ml/m2 a.i) for Multrazine; and control was included. The experiment was conducted in a split-plot design with six replicates arranged in a Randomized Complete Block Design. Moist soil samples were randomly collected from treated and control plots at the depths of 0-5 cm, 5-10 cm, 10-15 cm, and 15-20 cm, with an 8.5 cm2 diameter bucket-type auger. A total of 1080 soil microarthropods comprising of 931 mites and 149 Collembola were recorded. Oribatid mites were the dominant group being present at each sampling period. Total soil micro arthropods collected were 554 Oribatid mites, 377 Mesostigmata and 149 Collembola. The highest number of soil micro arthropods was recorded from the control treatment although this was not significantly different from the numbers recorded from low and standard doses of Glyphosate. All the three levels of Multrazine treatments significantly reduced the population of micro arthropods compared with all the three levels of Glyphosate. Both herbicides completely eliminated Collembola from the treated plots. In all the treatments, fewer soil micro arthropods were recorded as soil depth increased.