Sampling for Soil Microarthropods By Jill Clapperton (PhD) Principal Scientist Rhizoterra Inc.

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1 Sampling for Soil Microarthropods By Jill Clapperton (PhD) Principal Scientist Rhizoterra Inc. Disclaimer- this is not the children version this procedure it for adults and older children with adult supervision. You will be using tools that can cut, and liquids that are unsuitable for children. Please keep you extractors out of the reach of children. Soil fauna drive decomposition by chewing larger pieces of organic material into smaller pieces. The manure pellets they leave behind increase microbial activity, and improve soil structure. Many of these animals (particularly collembola) have a preference for consuming dead plant material that is colonized by fungi- think of how this might affect plant disease cycles. Looking at the diversity and abundance of soil fauna between field treatments: such as till and no till, cover crop and no cover crop, cropped and fallow, can give us an idea of how healthy our soil is. We need predator prey relationships to drive nutrient cycling so the plant has a chance for nutrients that might otherwise be tied up by the bacteria and fungi. These animals sit in the middle of the food web and are indicators of both the quality and quantity of soil organic matter. There are a number of ways to extract microarthropods and other microscopic animals from soil. One of the most common methods is using a modified Berlese Funnel (in our case extremely modified). The idea is to use light and some heat (that creates a moisture gradient) to keep the animals in the intact core moving downwards until they drop out of the core and into our catch solution. There is no putting the animals back in the soil at this point. This method will allow even the juveniles to escape into the catch solution. You will need to monitor the level of the solution in the bottom of the extractor- it must never dry up. The best time to sample for mites, collembola and other soil micro fauna is in the fall, and/ or early spring. You will be cutting a soil core- with the litter layer intact. Eventually the core will go into the pop bottle extractor so you want you core to fit easily inside the larger diameter of the pop bottle. Disturb this core as little as possible. I use a soup can to cut the core that is no more than 5 cm deep (you can use a trowel as well but the cores collapse easily). If you are interested in the affects of depth on soil animals: take the first core from the top 3-5 cm (1-1.5 inches), and then take a second core to 10 cm. Wrap the core in a porous cloth, and put it into a container that will keep the core up right and stable while you transport it. If the cores are really dry when you are taking them- water the ground and then take the cores (this is cheating of course, but for this course you can cheat). Label your containers well. You might want to bring your animals with you to the workshop. In this case please use alcohol to preserve them, freeze the sample, or extract within a few days of coming to the workshop. Store your samples in a sealed container in a cool place. Please bring a magnifier with you. 1

2 You will need: The next step is making a Pop Bottle Extractor You will need: 1. A desk lamp or a string of lights with incandescent bulbs use low watt bulbs. Clear Christmas style (not LED lights) work really well ml (16 oz) or 1 liter (32 oz) pop bottles- Please use clean and rinsed the bottles. 3. J-Cloth style cloths or cheese cloth 4. A knife or scissors to cut the bottle. 5. Dish soap you will only need 1 drop/ extractor 2

3 Select a plastic bottle- I prefer 1 liter (32 oz) bottles. Scissors or a utility knife can be used to cut the bottle. This is an adult activity and not suitable for children. 3

4 Cut the top off the plastic bottle so you make a funnel to hold the core. First you need to identify the sites you want to compare this could for example be- 2 different cover crops, grazed and ungrazed, tilled and no till. Then you need to prepare to take the sample. Cut away all the living plant growth to the surface of the litter layer. 4

5 Now cut a core that will fit into the funnel of your extractor- a soup can sized core will fit inside a 1 liter (32 oz) bottle. Use a sharp edged can or a knife to cut the core this is an adult activity. For children you can use a trowel or child safe tools to cut the core. You will cut the core 3-5 cm deep 5

6 Place the core on a porous cloth like this or cheese cloth just enough to wrap the core and then place the core in your plastic container. Assembling the core in the extractor- I needed to cut the bottle again so the funnel was 8-10 cm (approx. 2 in) from the bottom of the bottle. 6

7 Place the core wrapped in cloth in the funnel, add about 1 cm of water to the bottom of the bottle, and then add 1-2 drops of dish washing liquid soap. The last thing you need is the low watt light do not let the cloth touch the light in any way. Place the light over the core in the extractor and leave the light on for 3-5 days. Check daily and add water if necessary- do not let the collecting fluid in the bottom dry out. The top will get dry. If you want you can spray the top of the core with water. Trim the cloth if necessary so the core is exposed to the light and marginal heat from the light. 7

8 About the collecting fluid If you use water with soap to catch the bugs that crawl out of your sample- you must look at them after 3 days or they will start to rot. Alternatively you can use methylated spirits or some kind of clear alcohol (like vodka) to preserve the samples. This is also a responsible adult step and not for children and students. Methylated spirits are toxic and cannot be consumed. Be safe and keep this out of the reach of children. Transfer the liquid every couple of days to a jar or clear container and put it in the fridge or a cool place to store do not add liquid. Be safe and keep this out of the reach of children. You can pour the liquid onto a small white plate and observe with a USB microscope attached to your computer, use a magnifying glass with a light (like the quilters use). The following on line identification keys will assist you to ID what you are looking at Photo Val Behan-Pelletier AAFC Ottawa Canada. 8

9 This is an example of an soil microarthropod extracting assembly made by a dairy farmer in South Africa. He is comparing samples from pastures that have been seeded to different forage mixtures. Keep these out of reach of children if you are using methylated spirits or alcohol in the bottom of the bottle. 9