Effects of weed management on densities of subterranean collembola in soybean

Collembola are abundant soil organisms that can affect plant production via nutrient cycling, rhizosphere interactions, and food web dynamics. With the widespread use of the broad-spectrum herbicides, questions have arisen about potential impacts on soil dwelling arthropods. Since they are sensitive to changes in the soil environment, Collembola are ideal study organisms, although in many cases only the epigeal community is assessed. Therefore, we investigated how weed management impacted densities of subterranean Collembola in two soybean fields that differed in soil type. At each location there were three treatments established using a randomized complete block design: 1) control with no weeds removed 2) glyphosate (32oz/acre, applied twice) and 3) hand weeding. This design allowed us to separate effects of glyphosate on Collembola from effects of the weeds themselves. Experimental plots were 30 x 30 ft and were replicated six times at each location. To quantify soil arthropods, we took four soil cores (6 x 4.25 in) from each plot eight times over the course of the growing season using a golf cup cutter. Soil cores from each plot were combined and Collembola were extracted using Berlese funnels. Density data were log (X+1) transformed and analyzed using repeated measures factorial ANOVA and Tukey’s posthoc test with weed management and location as the independent variables. We also quantified weed pressure, and soil pH, nutrient, and moisture content. We will discuss how the above weed management strategies and soil factors affect densities of Collembola and potential agricultural and environmental implications.