Читать книгу Fieldwork Ready - Sara E. Vero - Страница 25

Fieldwork doesn't necessarily mean that the experiment itself is conducted outdoors. You may need to collect materials for use in controlled, laboratory tests. For example, studies of microbial respiration using incubation chambers need substrate such as soil, sediment, manure, etc. Unlike agar, purified water, or any other common laboratory material, you need to find, sample, and retrieve these samples from the field. The advantages of these studies include the ability to control microcosms to a degree which is largely impossible in situ, the opportunity to apply multiple treatments and the potential for replication and subsampling. Furthermore, you are not as logistically constrained as when you must return to the field for repeated sampling. Sounds ideal! However, you should not underestimate the challenges.

Let us take an example. You want to investigate CO₂ emissions from a range of soil types treated with a commercial amendment. Each incubation chamber requires 150 g dry weight of soil and you want to apply three rates of amendment plus an untreated control. You plan on using four replicates and four different soil types. This means you need 64 chambers, each with 150 g dry soil, or 9.6 kg. That doesn't seem like a lot but consider that you are not sampling dry soil in the field. You will collect the substrate by digging blocks of soil from 0–15 cm, removing the root mat, and aggregating. Samples will be air dried, sieved to 2 mm, and finally packed to a specified bulk density in the chambers. First, consider that field soil is not equivalent to dry soil as it contains both solid mineral particles and pore water (typically up to 25% or 30%, depending on soil type and recent weather). Therefore, much of the sample you collect in the field will actually be water, which is of no use to you. Second, you do not need the large particles, roots, rocks, and pebbles, which will be sieved out. The proportion of your sample which will be made up of this surplus depends entirely on your soil types, but suffice to say, you will need to collect far more soil than the <10 kg dry weight equivalent that will actually fill your chambers. You will need a suitable vehicle for accessing the fields, sampling tools and containers, manpower, time, and all safety equipment, PPE, and other gear which you need when going to the field. Of course, this is just one example. You might be collecting vegetation samples for cultivation in a glasshouse, trapping wild animals for tagging and release; it all depends on your unique research. However, the same basic principles of fieldwork should be adhered to throughout sampling, even though the actual experiment will be conducted back at the laboratory. In summary, you should be equally prepared for the logistical challenges even if you are not running field trials or setting up observatories.