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Soil penetrometerSpring 2014
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https://works.bepress.com/david_a_bainbridge/37/
Soil penetrometer
A soil penetrometer measures the many complex factors that affect
soil strength. It chronicles the challenge a root tip will face in
extending into the soil. Soil moisture is an important aspect of
this, so measurements between sites are best used as comparisons on
a given date. Measurements across time are also useful, but will
reflect seasonal changes in moisture. A gravimetric soil moisture
measurement can be helpful to compare different sites at different
times. Bulk density measurements or organic matter measurements can
also add more detail to your understanding of the site soil. Mid-
Spring is often a good time to sample as it is likely to be the
most important time for plant establishment and exhibit the
greatest differences in moisture content.
Procedure Clip a new strip of 2” wide tape on the stick after
slipping it
under the slide frame. Remove the slide hammer snubber cord. Label
the tape at the top with the date, site name and specific
location and your initials or name. Hold the penetrometer
vertically where you wish to measure
soil strength by holding the wooden stick at a comfortable
height.
First hold the tip of the penetrometer at the soil surface and make
a mark on the tape using the top of the sliding frame to guide your
pen. Label this S for soil surface. Hold the pencil or waterproof
pen at the same angle for every mark.
With the weight at the bottom of the slide let the tip penetrate
into the soil by its own weight, mark a line on the tape at this
point and label this F for free fall.
Then lift the slide hammer to the top of the shaft and let it drop,
marking the tape after each drop. I usually make the 5, 10, 15, 20
lines longer to help in later data writeup.
Don’t throw or force the hammer to drop, just lift it and let it
drop in freefall. If you hold the pen in your hammer hand this can
go quite quickly. Keep the penetrometer vertical for each drop by
keeping your holding arm in the same position (you can also put a
two way level on the stick but it is not necessary once you get
used to it. A second person holding the stick makes it faster and
easier.
If you hit a rock and penetration stops, start over again nearby.
The pin can penetrate a considerable distance in soft soils, but
the most important soil characteristics are usually within the top
0-30 cm where a seedling would start to grow.
For a rapid survey you might just mark hits at 5, 10, and 15 drops.
In dry hard soils you may only get in 5 cm after thirty drops. No
sense spending more time if the pin is not moving. If you drive the
pin in too deep in hard ground it can be hard to pull out. Pull up
on the lower part of the pin.
After you reach the end of the sampling remove the tape and fold it
neatly. I prefer to keep the paper tapes in a ziplock plastic bag.
This keeps them dry and clean and easier to sort out when you get
back to the lab.
David A. Bainbridge sustainabilityleader@gmail.com
Simple impact penetrometer, Ant Hill Restoration Project Anza
Borrego Desert State Park
Restoration Notes v2n3 2014
Equipment and vehicle operation, agricultural operations, horses,
mountain bikes, and pedestrians can leave a lasting legacy of
compacted soil. This can reduce infiltration, slow or prevent root
growth, and prevent or inhibit vegetation recovery.
Serving Sizes
Plotting Trim the tapes and lay them out on lined white
paper,
matching soil surface lines to a bold line running across the top
of the paper. Transfer all needed information on site location.
Tape them down with clear tape, leaving room between tapes to note
distances. Then lay your mm ruler on the center of the marks and
note the distance to each line from zero at the soil surface line.
Transfer the numbers to the excel spreadsheet. I use negative
numbers because I think it makes more intuitive sense to see the
plot this way.
Compacted soils on project sites can be improved by breaking up the
soil as deeply as possible. This should be done without inverting
the soil layers to maintain a natural fertility gradient.
A ripping tooth, backhoe bucket with teeth, spader or auger can be
used to de-compact soil. A spader instead of a tiller should be
used to prevent soil inversion. A garden fork, square tine, can be
used to decompact soils that are not in extremis, but for severely
disturbed sites powered equipment will be needed.
CLIP LOCK THE FRAME for TRAVEL If you will be walking to the site
or between sample locations with
the penetrometer use the big clips to lock the sliding frame in
place with the clips on the yellow marks. Use the small elastic
cord to secure the slide hammer to avoid pinches. Carry the
penetrometer by holding the wood stick about mid-frame for
balance.
Not full scale
Build your own penetromer for about $50 It is not difficult to make
your own soil penetrometer. The parts
can be found at hardware, auto supply (slide hammer for dent
removal), and office supply stores. I experimented quite a bit
before settling on this design and it has worked faithfully for
more than 20 years. It was also loaned and used by others.
For several years I had a self-marking version that marked the tape
when the hammer was lifted--but it eventually succumbed to rough
treatment in the back of field trucks. You may find it a help if
you will be working alone. I used a double linkage lever to swing
the pencil stub.
The 1 kg hammer with 6 mm blunt bullet shaped tip was best and
resisted damage when hitting rocks. A drop height of 60 cm gave
good penetration on commonly encountered soil conditions.
Weld on the sleeve to act as the anvil for the dropped hammer. The
drill extension can be welded to the rod but will be stronger if it
is placed in a drilled hole in the end of the slide bar first. Weld
cross bar at the top.
The drill bit extension has a hex set screw so that you can change
tips. To maintain this function over time the hole must be tapered
slightly so the mashing doesn’t lock the tip in.
Round off the edges of the wood stick, all brackets and metal
edges. Nylock nuts improve durability.
Metal handle used as slide guide, hinge used as cross bar
UHMW plastic strips used to build guide channel
For more information on soil strength and treatment of compacted
soils see:
Bainbridge, D. A. 2007. A Guide to Desert and Dryland Restoration.
Island Press, Washington, DC.
Bainbridge, D. A. 1993. Soil compaction. Land and Water.
37(1):42-43.
http://works.bepress.com/david_a_bainbridge/subject_areas.html
http://alliant.academia.edu/DavidBainbridge
www.sustainabilityleader.org
Sostenga el penetrómetro verticalmente donde se desea medir la
resistencia del suelo sosteniendo el palo de madera a una altura
cómoda.
Primero sostenga la punta del penetrómetro en la superficie del
suelo y hacer una marca en la cinta con la parte superior del marco
de deslizamiento para guiar su pluma. Etiqueta de este S para la
superficie del suelo. Sostenga el lápiz o la pluma a prueba de agua
en el mismo ángulo para cada marca.
Con el peso en la parte inferior de la diapositiva que la punta
penetre en el suelo por su propio peso, marque una línea en la
cinta en este punto y la etiqueta de esta F para caída libre.
A continuación, levante el martillo deslizante hacia la parte
superior del eje y la dejó caer , marcando la cinta después de cada
caída. Normalmente suelo hacer los 5 , 10 , 15, 20 líneas más para
ayudarle en writeup datos más tarde.
No arroje ni forzar el martillo para caer, tan sólo levante y la
dejó caer en caída libre. Si mantiene la pluma en la mano un
martillo que esto puede ir bastante rápido . Mantenga el
penetrómetro vertical para cada gota, manteniendo su brazo de
sujeción en la misma posición (también se puede poner un nivel de
dos vías en el palo, pero que no es necesario una vez que te
acostumbras a él. Una segunda persona que sostiene el bastón hace
que sea más rápido y más fácil.
Si usted golpea una roca y paradas de penetración , empezar de
nuevo cerca. El pasador puede penetrar una distancia considerable
en suelos blandos , pero las más importantes características del
suelo son por lo general dentro de los 0-30 cm superiores , donde
una planta de semillero comenzaría a crecer.
Para una encuesta rápida que sólo podría marcar imparables en 5 ,
10 , y 15 gotas. En suelos duros y secos que sólo puede estar en 5
cm al cabo de treinta gotas. No tiene sentido gastar más tiempo si
la clavija no está en movimiento. Si usted conduce el pasador en lo
profundo de la tierra dura que puede ser difícil de sacar. Tire
hacia arriba de la parte inferior del pasador.
Después de llegar a la final de la toma de muestras retire la cinta
y doblar prolijamente. Prefiero mantener las cintas de papel en una
bolsa de plástico ziplock. Esto los mantiene seco y limpio y más
fácil de resolver cuando vuelvas al laboratorio.
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Marking sites for remeasuring soil properties is challenging. These
stakes were too short and the paint and tape faded. Metal
fenceposts 1 m tall are better. Blue paint is often easier to see.
Reflective tape helps as well.
Disturbance impacts on soil strength, Anza Borrego Desert State
Park
uncorrected Google translations
Spring 2014
Soil penetrometer