Dear colleagues,
basically we intend to correlate lab measurements of soil stability (for details see below) with in situ measurements of soil stability. As in situ measurements we already have:
These methods are not all really simple and fast. So that's the point where I need your creative ideas.
My question to YOU: What other simple field measurements could possibly be correlated to soil stability and/or function?
It could also be something weird, or crazy, something I would not think of in first instance (e.g. sth related to electricity)
Thanks a lot for your feedback,
Malte
Background of the question:
Lab measurements, undertaken with samples from the field: pre-consolidation stress and cyclic compressibility, shear parameters, Atterberg limits, saturated hydraulic conductivity, air permeability, texture, water retention curve.
Explanation of the project:
My collegues an me want to assess the impact of heavy forestry machines (29t forwarder) on the stability and function of a loess soil (stagnosol). The trafficking experiments will be conducted on already existing skid trails in a spruce forrest. Different machine configurations (tyres, different kind of belts) will be compared with each other. For each machine configuration different trafficking frequencies and slope inclinations will be simulated.
Laboratory experiments are, as the name already says, very laborous and expensive. Therefore we want to try to correlate the results from the lab to results from the field measurements. WIth the resulting pedotransfer functions it might be possible to derive the parameters from the lab measurements just from simple field measurements, so that in future the laboratory measurements could be skipped. With these field measurements large areas of forest soils could be covered rather easily and hence could be used to create maps of loess soil stability. These maps could serve the rangers as a decision guidance for a soil conserving wood harvest.
Measuring differences by soil moisture levels may be a big factor. Indicators might be rainfall, water table depth, depth of ruts on first pass, PSI ground pressure of equipment, width of tires (I have seen really wide tires do a lot of damage in turning, even with fairly low PSI). Also, at what soil moisture might soils puddle (loose structure and become a slurry). In the past, quite a few soil scientists did research on this general subject in USFS and Universities. I believe Hank Froehlich, Oregon State, was one of them you might want to look up his research. Compaction also changes hydrology, typically making site wetter, less operable. Limb debris from trees can be used on designated skidtrails to reduce affected area and increase trafficability. The USFS has a soil quality monitoring guide out, available on internet, and it may have some ideas for field monitoring. Logging problem soils when relatively dry, adding in rolling dips to remove concentrated flow from steep skid roads into forest filter should help avoid rills and gullies possible with highly erodible soils. installing a couple of water wells with level transducer recorders (internet Onset Hobo or Global Water) will help keep track of conditions when logging or when to shut down if trying to develop BMPs. Also if soils are not consistent, have a soil scientist map them and classify their differences.
Maybe with a dynamic plate load test (acc. to TP BF-StB Teil B 8.3) if you find a way for the description of the correlation of the dynamic drop weight and the weight of the simulated machinery (scaling issue).
@ Petra Schneider. That looks quite promising but also not very cheap and simple. Do you happen to have one of these plate load testers that you could lend us?
Dear Malte,
I am not so long with the university, that's why I don't know. I sent a request to my colleage Prof. Turczynski from the geotechniques department if they have it and in case if they would rent it. And I will ask my former colleagues from the engineering office if they have the equipment in the geotechnical lab. Further I attached a related document, maybe it would be also feasible to rent it from a supplier. Some contacts are mentioned there. Maybe also this link could be helpful: https://www.terratest.de/fallgewichtsgeraet-mieten/. I come back to you after I received the response from my colleagues.
Best regards, Petra
Dear Malte,
it seems we could find a solution for lending the plate load tester through the University of Applied Sciences Leipzig, collaborators of us. Please send me your mail-contact to [email protected], and I will forward the conversation.
Best regards,
Petra
Dear Petra,
thanks a lot for your effort! I spoke with my prof. and unfortunately a dynamic plate load tester is not suitable for us. We want to know about the compaction under the more or less slow pressure of wheels. This is also what we measure in the lab with the oedometers. Under the short impacts of the weight of the plate load tester the particles compact differently than under more constant pressure, since the soil water can not disseminate in that short period of time and the partciles consequently slide along each other similar to the aquaplaning effect on roads. So what we would actually need is a constant plate load tester. To my knwodledge high weights are needed for this kind of constant pressure test in the field. This would not be one of these easy field methods I was looking for... Or do you happen to know of a possibility of constant pressure testing in the field with a small gadget, similar to the dynamic plate load tester?
Best regards,
Malte
- Badges
- Science topic
- Similar topics
- Agricultural Science
- Soil Science
- Soil Analysis