Plaintext
Landcare
RASH Manual
A landholders guide to the
Rapid Assessment of Soil Health
General Edition v1
Landcare RASH
This Extension Manual was written by David Hardwick at Soil Land Food. It has been
published by Little River Landcare Inc. as part of the “Topsoil Thinking Project 2014”. Little
River Landcare Inc. & Soil Land Food wish to thank the landholders, individuals and sponsors
who have supported the project and this publication. References & Acknowledgements are at
the back of this publication. All Photos are by David Hardwick & Thea Ridley, except where
otherwise acknowledged.
www.littleriverlandcare.com.au
www.soillandfood.com.au
It is Licensed under a Creative Commons 3.0 License.
Disclaimer: This publication is provided in good faith and based on the most appropriate
technical information available. However this information is given as a guide only and its use
depends on many factors beyond the control of Soil Land Food & Little River Landcare Inc.
Therefore Soil Land Food & Little River Landcare Inc. or their representatives accept no
liability arising out of the use of this publication, for any loss, damage or injury. The user uses
this publication on these terms.
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How to use this Manual
The Landcare RASH Kit is a tool to help you assess your soil's health and some of its
key properties. Soil is the most valuable natural asset on your property. Without a well
functioning soil farm productivity will not be optimal. Use this Manual to help you
objectively assess the condition of the soil on your property.
Monitoring the condition of your soil can help you can make decisions for better soil
fertility and paddock management. It can help you identify any major soil constraints.
Accurate monitoring of soil health can also help you track whether your management
practices are maintaining your soil, improving it or degrading it. Use the Landcare
RASH, along with an agronomic soil test, and allocate 1 or 2 days a year to assess and
monitor the condition of one of your most important farm assets – your soil.
5 Steps to Soil Health Assessment
1. Check your equipment: Make sure you have all the equipment you need and it is
all in working order. The Equipment List is on Page 5.
2. Prepare your soil sampling approach: You should have a well thought out
sampling site and need to decide when and how often you will do a soil health
assessment. A Guide to Sampling is on Page 6.
3. Assess each Soil Health Indicator using the guidelines in this Manual: Follow
the steps in this manual to complete a soil health assessment. The assessments
start on Page 8.
4. Fill in a RASH Score Card as you go: Score Card Sheets are provided in the Kit
and you can make photocopies if required. As you assess each indicator just fill in
the Score Card. Instructions on using the Score Card are found at the end of this
manual on Page 28.
5. Tally your score and review the results: Once you have scored your soil's health
and key properties you can evaluate it against benchmarks and identify areas
where you may need to take management action. See the Troubleshooting Guide
on Page 29.
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The RASH Indicators
Soils have three key aspects to their fertility and condition: Physical, Chemical &
Biological. All are important and all influence each other. A healthy soil is one that is in
good condition across all three areas. This will result in a well performing soil ecosystem.
The RASH approach assesses key indicators in all three areas. It uses practical indicators
that can be monitored in the field or in the farm office at little cost. These indicators can
be measured fairly easily and are known to be key properties that strongly influence soil
function and fertility. There are 10 main indicators used as part of the RASH approach.
These are the Base Indicators.
There are other soil health indicators that you may want to add to your monitoring.
These can be used to get a more detailed picture of your soil's condition. They take a bit
more time and effort but can be well worth it. These include monitoring earthworm
numbers, assessing dung beetles, measuring bulk density and assessing root
characteristics.
Base Indicators
Physical:
Soil Texture …..................... page 8
Groundcover....................... page 10
Soil Infiltration.................... page 12
Aggregate Stability.............. page 14
Chemical:
pH...................................... page 16
Salinity............................... page 18
Sodicity.............................. page 20
Biological:
Root Depth........................ page 22
Root Volume...................... page 24
Soil Organisms................... page 26
RASH Score Card
Score Card.......................... page 28
Troubleshooting Guide......... page 29
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Equipment
The RASH Kit that accompanies this manual contains most of the equipment you need to
carry out assessments of your soil health. There are a few additional items you will need
to get from your farm shed or the hardware store. These are also listed below. Before
doing a RASH it is a good idea to check that all your equipment is in working order. This
includes the batteries in the pH/EC meter if you are using one. Make sure that you clean
all the items and pack them away into the kit after you finish. If you do not have access
to a RASH kit and want to make your own then just use this list to develop your own.
RASH Kit Equipment
Mortar & Pestle - 1 Mallet - 1
Water Bottle Plastic - 1 Tweezers - 2
Paper Hand-towel Plastic dish/petri dish - 5
Soap Plastic Tray white - 2
Liquid Paper pH/EC Hand-held Meter – 1 (or pH kit)
Groundcover Worksheets Calibration fluids & Instructions for Meter
Calculator - 1 pH Colour Test Kit – 1 (or pH/EC Meter)
Pens - 5 Screwtop Plastic Container 20 ml marks - 2
PVC Tube with bevelled edge - 1 Steel Ruler - 1
Jug – 500ml plastic - 1 Magnifying Glass/Hand Lens - 1
Scissors - 1 Soil Organism ID Guide
Stopwatch - 1 Cling-wrap
Plastic Sheet - Heavy duty - 1 Wooden Block – 1
RASH Quick Guide Sheets RASH Score Card
Additional Equipment
You will need to gather this additional equipment from the farm shed, the hardware store or the
supermarket.
Spade Camera
Mattock GPS
Plastic Buckets - 10L Distilled Water (Rainwater is next best) - 10L
Extra Water - 20L Wooden Board approx. 0.5m by 0.5m (or larger)
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Sampling the paddock for soil health
It is important to take a consistent approach to your sampling when assessing soil
health. It is recommended that your soil health monitoring sites be chosen based on soil
type and land management units. Soil type influences the key properties of a soil greatly.
Therefore it is better not to mix up soil types when scoring soil health. It also important
to separate out different areas of management as tillage, fertiliser use, farm traffic and
other practices will modify soils greatly even if they are the same soil type.
Obviously farmers are mainly interested in the soil health of the actively farmed areas of
the property. So this is where to set up a monitoring site. However it can be very helpful
to also set up a monitoring site in a non-farmed area like natural bush or a unused area
of grass as a comparison.
4 Key Steps to good Soil Health sampling
1. Locate your Monitoring Sites: You need to decide where you will set up your
Monitoring Sites. Use a farm map to set up one or more Monitoring Sites in your
management areas. Stay within the same soil type for each Monitoring site. Also
stay within the same Land Management Unit for each site. Write the Location on
the RASH Score Card.
2. Set out your sampling transect: The RASH method requires you sample at
least 5 points along a transect or straight line. This needs to start from an
identifiable point in the paddock/orchard or from a GPS point. You can then
decide how far to space each of your 5 sample points apart. A minimum of 5
meters is recommended. In large paddocks you may have 20m between points.
3. Decide on when you will sample: At least once a year is recommended,
although ideally 2 or 4 times a year is better. It is important to sample around
the same time each year. In areas with seasonal rainfall it is important to pick a
time of the year when the soil is not dry but is not too wet. In tropical areas it is
best to sample in a drier month when the soil is not waterlogged if possible. The
soil needs to be moist when sampling. A few days after good rain is ideal.
4. Take a soil sample at each sample point: At each of the 5 sample points
you need to take a sample of soil to do the assessments. This involves using a
spade to dig out two cubes of soil that are approximately 20cm by 20cm by
20cm following the instructions on the next page.
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Sampling the paddock for soil health
Setting out your sampling transect
In this paddock of broccoli you In this pasture paddock you could In orchards and vineyards you
could set your transect up along lay your transect out across the can do 2 transects. Sample in
the contour to ensure similar slope. If it is all one soil type then row as well as in the inter row.
moisture conditions. you could space the 5 sample points In tree crops sample just under
out to 20m intervals. the drip line.
The key things when setting out your transect are: stay on the same soil type, stay in the
same management unit, stay in the same part of the landscape, sample when the soil is moist
at a similar time each year & use the same area for the transect each time.
Sampling at each sampling point
At each sample point dig Carefully lift them out of Place them on the plastic Use one cube to measure
out two 20cm cubes with a the ground. sheet or a wooden board root depth, root volume
spade. or similar. and then soil organisms
The other can be broken
up carefully to measure the
other indicators.
It can be difficult to get an
intact soil cube from a
sandy soil. You may need to
carefully lay the soil out on
the sheet noting which is top
and which is bottom.
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Soil Texture
What is it:
The texture of a soil is an estimate of the proportion of sand, slit and clay that it
contains. It gives either a gritty, silky or smooth feel to a soil depending upon how much
of these three fractions are in any soil type.
Why it is important:
Texture strongly influences a number of other soil properties including structure, water
infiltration, water holding capacity and ease of tillage. Texture does not readily change as
it is an inherited property. The soil texture depends mainly upon the type of rock that a
soil is formed from. Therefore it is important to determine texture as a first step in
assessing Soil Health.
How to assess it:
Soil texture is assessed by the way soil behaves when a small handful of it is moistened
and rolled into a ball or bolus in your hand. This ball is then pressed out between your
thumb and forefinger to form a ribbon. The strength and feel of the bolus and the length
of the ribbon formed are then rated against a chart to see what texture the soil has.
There is no good or bad value with soil texture. All soil textures, sandy, silty and clayey,
have advantages and disadvantages. Then write your texture on your RASH Score Card.
Equipment List
From the Kit:
Water Bottle, Hand towels, Mortar & Pestle, Soap, Pen, Scorecard
Additional:
Distilled Water, Spade,
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Assessing Soil Texture
1 – Get a sample of 2 – Moisten the 3 – Shape the moist 4 – Shape the sample
soil in your hand. sample sample into a into a ribbon and press
Remove any roots and ball/bolus. Assess how it out between thumb
gravel. well the bolus stays and forefinger.
together. Its coherence. Measure the length of
the ribbon that forms.
Be sure not to add too much water to the sample as you work it in your hand. As you handle
it note whether it feels sandy, smooth and silky or handles like plasticine. Finally press out
and measure 4 or 5 ribbons from the sample to get an average ribbon length.
Assessing your Soil's Texture
Evaluate your sample against this table for Bolus Coherence, Feel & Ribbon length. Then work out
your texture type.
Bolus Coherence Feel Approx. Ribbon Soil Texture Comments Approx. %
length Type Clay content
Nil to slight Sandy & gritty Less than 15mm Sand Unable to form a ball, Up to 10%
single grains stick to
fingers
Slight to just firm Sandy 15-25mm Sandy Loam Sand grains can be 10-25%
seen or felt
Firm Smooth, spongy Approx. 25mm Loams Can feel spongy or 20-30%
& may be greasy silky, no sand can be
felt
Firm to Strong Sandy 25 -40mm Sandy Clay Sandy to touch with 20-30%
Loam grains visible in finer
matrix
Firm to Strong Smooth 40-50mm Clay Loam Smooth to touch 30-35%
Strong plastic bolus Plastic 50-85mm Light Clay Smooth like soft 35-45%
plasticine
Strong plastic bolus Plastic Greater than 85mm Medium – Smooth and handles Over 45%
Heavy Clays like plasticine
Source: NSW DPI 2007
Write your soil's texture at the top of your RASH Score Card
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Groundcover
What is it:
Groundcover is any material that covers bare soil and protects it from exposure and
degradation and erosion. It can include living plants (pastures, crops and weeds) dead
plant litter, mulches as well as stones and in grazing systems can also include manure.
Why it is important:
Exposed soil can be degraded in a number of ways including by wind and water erosion
as bare soil is stripped away. Raindrops impacting on bare soil can also damage the
structure of soil at the surface. This leads to less water infiltrating the soil and more
running off. Having adequate Groundcover is the most effective way of increasing water
infiltration into the soil. Having plenty of plant material, including living plants, on the soil
surface also helps to maintain organic matter levels in the soil and can help increase the
number of soil organisms in the soil as they use Groundcover materials as food and
habitat.
How to assess it:
There are 2 quick ways to assess Groundcover in the paddock. Using the Step Point
method you walk along your sample transect and every step you stop and look down at
what is at the toe of your boot: bare soil, plant litter, plants etc. Then you mark this
down. You do this 20 times along the transect. You can then tally the results up and work
out a ground cover figure. The other way is to do a Visual Estimation method where
you use a wire square quadrant and estimate visually how much cover is inside the
quadrant when you place it on the ground along the transect. The end result of either
method is a Groundcover % figure for your sample area. This can now go on your RASH
Score Card.
Equipment List
From the Kit:
Liquid paper, Groundcover Worksheet, Calculator, Pen, Scorecard
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Assessing Groundcover
Step Point Method
1 - Identify your transect & get 2 - Mark the toe of your 3 - Step out along the
the Groundcover Worksheet boots with Liquid Paper transect
4 - At each step look down 5 - Record each observation on 6 - Tally up the observations &
and note what you see the Worksheet calculate % Groundcover
Scoring Groundcover
Once you have calculated your % Groundcover for your transect on the Groundcover
Worksheet, now score your Groundcover levels using the table below:
Rating Poor Moderate Good Very Good
Description Less than 50% Between 50% & Between 70% & Over 90%
70% 90%
Score 0 1 2 3
Now write the score for your Groundcover assessment on your RASH Score Card.
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Soil Infiltration
What is it:
Infiltration measures how readily water will enter the soil through the soil surface. It
shows how well rainfall will enter into a soil and not run-off.
Why it is important:
The more rainfall that enters the soil profile the more will be available for plant growth.
So it is important that as much water enters the soil during each rainfall event.
Otherwise water will run-off and can cause erosion. The infiltration capacity of a soil is
also related to its structure. So the better the infiltration, the better the structure. This
means the soil will have better soil air properties and plant roots will grow more easily
into the soil.
How to assess it:
Infiltration is measured by pouring a known volume of water into a piece of PVC pipe that
is hammered into the ground. Using a stopwatch you can time how quickly the water
disappears into the ground. From this you can estimate the infiltration rate per hour of
water in mm. Then score your sample using the RASH Score Card.
Equipment List
From the Kit:
PVC Tube, 500ml Plastic jug, Scissors, Stopwatch, Cling-wrap, Wood Block, Mallet, Pen,
Scorecard
Additional:
Fresh water & bucket
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Assessing Soil Infiltration
1 - Get all your 2 - Use scissors to clear 3- Hammer in the PVC 4 - Lay Cling-wrap inside
equipment excess vegetation if required tube using a block. Make the tube – optional.
sure it is level and firmly
in the ground.
5 - Pour 500ml of water 6 - Carefully pull out the 7 - Time how long it takes 8 - Record your results
into the tube cling-wrap the water to infiltrate on the Scorecard
Scoring Infiltration
Now you have assessed the infiltration rate you can score the soil on its infiltration.
Rating Poor Moderate Good Very Good
Description More than 10 mins 3 to 10 mins Less than 3 mins Less than 1 min
but more than 1
min
Score 0 1 2 3
Source: SoilCare 2007
Write the score for each assessment onto your RASH Score Card
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Aggregate Stability - Slaking
What is it:
Aggregate stability refers to the ability of soil aggregates or crumbs to keep their
structure when put under stress. Soil aggregates that hold together indicate that the soil
structure will be stable and the soil will be in better condition. Unstable soil aggregates
can either slake , where they fall apart into smaller crumbs; or disperse , where
aggregates dissolve into individual soil clay particles. Clay levels and organic matter are
what gives a soil good structure and reduces slaking. Dispersion, another aspect of
aggregate stability, is an indicator of soil sodicity, whereby there is excessive
exchangeable sodium in the clay minerals of a soil. This is measured later in the RASH
approach.
Why it is important:
Good structure is important for all soil functions. It ensures better plant root growth,
better soil air and water cycles and it improves the habitat for soil organisms. It also
means the soil can cope better with agricultural activities like tillage and traffic without
soil condition declining too much.
How to assess it:
Aggregate stability – Slaking, can be measured using the Aggregate Stability in Water
Test (ASWAT ). A small air dried aggregate of soil (3-5mm) is placed into a shallow dish of
distilled water and then it is observed over a period of 10mins. It is observed for slaking
over this time and then an ASWAT score for slaking can be given. Then score your
sample using the RASH Score Card. Dispersion which measures potential sodicity in a soil
can be measured at the same time. See page 20. For this test it is a good idea to air dry
the soil for 24-48 hrs before hand.
Equipment List
From the Kit:
Tweezers, Plastic/Petri Dishes, Stopwatch, Wooden Board, Pen, Scorecard
Additional:
Distilled Water
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Assessing Aggregate Stability - Slaking
This test and the test for Soil Sodicity (page 20) both use a similar method. They can
therefore be done at the same time using the same sample. Take your soil from 10cm depth. It
is better to air dry the soil for 24-48 hrs before doing this test.
1: Pour distilled water 2: Get a small 3 – 5 mm 3: Carefully place it into 4: Using a timer leave the
into your petri dish or aggregate from 10cm a dish. Use tweezers if you sample for 10 mins. Then
plastic bowl. depth that has been air need to. observe how much the
dried for 24-48 hrs. slaking has occurred at
the 10 min mark.
At the 10 minute mark you can assess the level of slaking you observe. Either:
Nil Slaking Slight Slaking Strong: Up to 70% Slaking Complete Slaking
Then Score your sample:
Ausveg 2007
Nil Slaking Strong Slaking
Scoring Aggregate Stability
Now you have assessed the sample for slaking you can score this soil for aggregate stability
using the table below:
Rating Poor Moderate Good Very Good
Description Complete Collapse Strong: Up to 70% Slight: Edges No slaking at all at
at 10 mins collapse at 10mins collapse only at 10 10 mins
mins
Score 0 1 2 3
Now write the score for each assessment onto your RASH Score Card
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Soil pH
What is it:
pH is a measure of how acidic or how alkaline overall soil conditions are. It really
measures the amount of free Hydrogen (H) and hydroxyl (OH) ions that are in a soil. The
biochemical processes that occur daily in soils always result in a balance of acidity and
alkalinity and give a soil its pH. However some natural processes as well as many
agricultural practices can increase the acidity of a soil and make conditions less suitable
for many agricultural crops.
Why it is important:
The pH of a soil strongly influences a number of soil processes including nutrient
availability and soil biological processes. Under highly acidic and highly alkaline
conditions a number of nutrients may tie up or become unavailable. Under acidic
conditions some toxic elements like aluminium and manganese may become available
and create toxic conditions for plant growth.
How to assess it:
pH in the field can be assessed by either using a hand-held pH meter or using a pH
powder indicator kit. The hand-held meter is inserted into a beaker with a 1 to 5
soil:water solution in it. A reading is then taken off the meter. Using the powder indicator
kit a sample of soil is mixed with a solution and then dusted with a reagent powder. The
sample then changes colour and the colour can be assessed against a colour chart to
determine the sample's pH.
Equipment List
From the Kit:
pH Test Kit or pH Hand-held Meter & Calibration Fluid, Screw Top Jar, Paper-towel, Pen,
Scorecard
Additional:
Distilled water
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Assessing Soil pH
Using the Hand-held Meter – make sure your meter is set to measure pH
1: Calibrate your meter 2: Fill the screw top jar to 3: Add 100ml of distilled 4: Let the jar settle for
following the instructions the 20ml mark with water. This should now about 5 mins. Then insert
in the Kit. crushed soil from either 10 be a 1:5 Soil solution. the meter and measure the
or 20cm depth with no Screw on lid and shake pH after the reading has
stones and roots in it. well for at least 3 mins. stabilised.
Using the pH Colour Test Kit
3: Mix in well to a thick
2: Squirt on the indicator 4: Add the reagent
paste.
1: Get a sample of soil solution. powder onto the sample
and place on card.
Which ever method you use, hand-held meter or the
test kit, you are aiming to measure pH at both 10cm
and 20 cm depths. So take soil from both depths. 5: Wait 1 min and
When you are finished remember to record your then compare the soil's
results! Rinse and clean the equipment after use. colour to the chart.
Scoring pH
Now you have assessed the pH of your sample score it using the table below. Do it for both
depths 10cm and 20cm:
Rating Poor Moderate Good Very Good
Description Less than 5 or From 5 to 5.5 or From 5.5 to 6 or Between 6 & 7
more than 8 7.5 to 8 7 to 7.5
Score 0 1 2 3
Now write the score for each assessment onto your RASH Score Card
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Soil Salinity
What is it:
Soil Salinity is a measure of how many salts are in the soil's soluble fraction. Salts in a
soil can occur naturally coming from the parent materials, they can move to a site
through the water cycles in a catchment or they can be added through heavy salt-based
fertiliser use. When salts rise to the surface on the soil they increase the salinity of the
soil. A low level of salts in a soil is normal as these are forms of soluble nutrients.
Excessive salts in the soil cause problems. There are a number of types of salts including
sodium, magnesium and calcium-based salts.
Why it is important:
Excessive soluble salts in a soil can adversely affect plant growth. The main effects of
different salts in the soil include preventing plants from taking in water due to osmotic
changes and causing toxic conditions. Some types of salts can also adversely affect soil
structure.
How to assess it:
Soil salinity is assessed by measuring the soil's Electrical Conductivity (EC). In the field
this can be assessed by using a hand-held EC meter. The hand-held meter is inserted
into a beaker with a 1 to 5 soil:water solution in it. A reading is then taken off the meter.
This gives you an EC 1:5 result. This then needs to be multiplied by a conversion factor
depending on your soil's texture to give you an estimate of soil salinity as EC e . Then you
can score your sample's ECe using the RASH Score Card.
Equipment List
From the Kit:
EC Hand-held Meter, Calibration Fluid, Screw Top Jar, Paper-towel, Pen, Scorecard
Additional:
Distilled water
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Assessing Soil Salinity
Using the Hand-held Meter – make sure your Meter is set to measure EC (Salinity). Take
your soil from 10cm depth. It is better to air dry the soil for 24-48 hrs before doing this test.
1: Calibrate your meter 2: Fill the screw top jar to 3: Add 100ml of distilled 4: Let the jar settle for
for EC following the the 20ml mark with water. This should now about 5 mins. Then insert
instructions in the Kit. crushed soil with no stones be a 1:5 soil solution. the meter and measure the
and roots in it. Screw on lid and shake EC1:5 after the reading has
well for at least 3 mins. stabilised.
If you have a Combo Meter that can measure both pH and EC in the one unit then you can use the
same 1:5 soil solution to do both readings one after each other. This means that you can skip steps 2 &
3 above. You still need to rinse the equipment and calibrate for EC before taking an EC reading. It
uses a different sensor on the meter.
Converting EC1:5 to Soil Salinity ECe
To convert your salinity measurement to a soil salinity level you need to
multiply your EC1:5 by a conversion factor depending upon your soil's
texture. See the Table below.
Soil Texture Conversion Factor
Sand 17
Sandy Loam 14
5: Convert EC1:5 to ECe. Loam 9.5
Now you have to convert the
Clay Loam/ Light Clay 8.6
1:5 salinity result to get a
Soil Salinity measurement Medium & Heavy Clay 6.7
(ECe). Use the Conversion Example with Light Clay and EC1:5 of 0.15 dS/m:
Table to the right.
0.15 dS/m X 8.6 = 1. 29 ECe Source: NSW DPI 2007
Scoring Soil Salinity
Now you have determined the Soil Salinity (ECe) of your sample score it using the table below:
Rating Poor Moderate Good Very Good
Description More than 6 Between 2 & 6 Between 1.5 & 2 Less than 1.5
Score 0 1 2 3
Now write the score for each assessment onto your RASH Score Card
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Soil Sodicity - Dispersion
What is it:
Soil Sodicity is a measure of how many sodium ions are in a soil relative to the calcium,
potassium, magnesium, aluminium and hydrogen ions. This sodium is in the
exchangeable clay fraction of the soil. When there is excessive sodium ions in the clay
fraction of the soil the soil is considered sodic. The sodium usually comes from the
parent materials or rocks from which the soil forms.
Why it is important:
Excessive sodium in the soil's exchangeable clay fraction leads to the soil's structure
collapsing and the clays dispersing. This can result in hard layers in the soil, crusting and
hard setting surfaces on the soil. Water infiltration is reduced and less air can get into
the soil. The end result is less than ideal conditions for plant root growth and soil
organism activity. Sodic soils are extremely sensitive to cultivation.
How to assess it:
Soil Sodicity can initially be measured using the Aggregate Stability in Water Test
(ASWAT ) as used for the Aggregate Stability Slaking Test previously. A small air dried
aggregate of soil (approximately 3-5mm) is placed into a shallow dish of distilled water
and then it is observed at the 10 minute mark and then again at the 2 hour mark. It is
observed for dispersion over this time and then an ASWAT score can be given for
dispersion. If this test indicates that dispersion is an issue then a laboratory test is
recommended to assess more accurately if the soil is sodic and will have management
issues before taking further action.
Equipment List
From the Kit:
Tweezers, Plastic/Petri Dishes, Stopwatch, Wooden Board, Pen, Scorecard
Additional:
Distilled water
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Assessing Soil Sodicity - Dispersion
This test and the test for Aggregate Stability (page 14) both a similar method. They can
therefore be done at the same time using the same sample. Take your soil sample from 10cm
depth. It is better to air dry the soil for 24-48 hrs before doing this test.
1: Pour distilled water 2: Get a small 3-5mm 3: Carefully place it into 4: Using a timer leave the
into your petri dish or aggregate from 10cm a dish on a flat surface. sample for 10 mins. Then
plastic bowl. depth that has been air Use tweezers if you need observe how much the
dried for 24-48 hrs. to. dispersion has occurred at
the 10 min mark.
At the 10 minute mark note the level of Dispersion you observe. Then leave until the two
hour mark and observe again. Then score the dispersion of the sample.
Nil Slight Strong Complete
Dispersion Patterns
5: Then observe how
much the dispersion has
occurred again at the 2 hr Source Photos 1,2 & 4 above: Ausveg 2007
mark.
Scoring Soil Sodicity
Now you have assessed the dispersion of your sample score it using the table below:
Rating Poor Moderate Good Very Good
Description Strong dispersion Slight dispersion at Slight dispersion at No dispersion at
at 10 mins or 10 mins or strong 2hrs 2hrs
complete at 2hrs
dispersion at 2 hrs
Score 0 1 2 3
Now write the score for each assessment onto your RASH Score Card
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Root Depth
What is it:
Root depth is the depth in the topsoil that the majority of roots of growing plants are
going to. This is the active area of soil where nutrients, water and carbon are exchanging
and soil life is at its greatest. Generally the deeper the roots are growing the better.
Why it is important:
The living and dead roots of plants are important to soil health in a number of ways.
They supply carbon to the soil and have a positive influence on soil processes, nutrient
cycling & soil structure. The deeper that plant roots go the greater the development of
topsoil and the more water and nutrients are available to plants for growth.
How to assess it:
Root depth is assessed by carefully turning your sample 20cm soil cube upside down and
counting if 15 easily visible roots are reaching through to the 20cm depth. If not then
trim 5cm off the bottom of the cube using a spade and a ruler. Then assess again. Do it
again at 10cm if needed. Root depth is the depth where 15 easily visible roots are
reaching to in the sample cube.
Equipment List
From the Kit:
Steel Ruler, Pen, Scorecard, Plastic Sheet
Additional:
Spade, Wooden Board
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Assessing Root Depth
Step 1: Get a cube of soil Step 2: Place the cube on Step 3: If there are less than 15
approximately 20cm each its side on a sheet and roots at 20cm then shave off 5cm of
side carefully count the roots at soil with a spade. Then recount.
20cm. Repeat again at 10cm if needed.
You are aiming to measure the depth at which 15 roots are
clearly reaching.
In a permanent pasture you should be able to assess the
Root Depth at any time during the year. Although pastures
may not be growing during winter, roots from autumn
growth should be present. In a cropped paddock assess
growth from mid to late stages of crop growth. In an
orchard assess root depth just under the drip line of the
trees.
In sandy soils keeping your cube intact can be difficult!
Handle it carefully.
When you are finished remember to record your results!
Source: Hardwick 2014
Scoring Root Depth
Now you have assessed the Root Depth of your sample score it using the table below:
Rating Poor Moderate Good Very Good
Description Less than 15 roots 15 roots at 10cm 15 roots at 15cm 15 roots at 20cm
at 10cm depth depth depth depth
Score 0 1 2 3
Now write the score for each assessment onto your RASH Score Card
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Root Volume
What is it:
Root volume is a measure of how much of a soil's space contains roots. In a healthy soil
plant roots should be able to fill much of the soil with roots as they grow. This indicates
that a large portion of a soil is actively exchanging nutrients, water and carbon.
Generally the more root volume the better.
Why it is important:
The living and dead roots of plants are important to soil health in a number of ways.
They supply carbon to the soil and have a positive influence on soil processes, nutrient
cycling & soil structure. The more soil space that plant roots fill the greater the
development of topsoil and the more water and nutrients are available to plants for
growth.
How to assess it:
Root volume is assessed by carefully taking 10 small aggregates (3-7mm) from your
sample 20cm soil cube at 2 depths: 10cm and at 20cm. Lay each set of ten aggregates
out on a plastic sheet or board. Then carefully break each aggregate open between your
fingers. Observe if you can see any roots inside each aggregate as you break it. Score a
point each time a root is found. Tally up how many aggregates had a root fragment inside
them. Then score both the 10cm and 20cm depth out of 10.
Equipment List
From the Kit:
Plastic Tray/Wooden Board or Plastic Sheet, Pen, Scorecard
Additional:
Spade
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Assessing Root Volume
Step 1: Get a cube of soil Step 2: Get 10 small Step 3: Break each
approximately 20cm each aggregates (approx. 5cm aggregate open and observe
side size) from the 10cm depth if roots are visible or not.
and lay them out.
You are aiming to measure root volume at both 10 and 20 cm
depth. In very heavy clay soils you may need to drop a clump
of soil from a height onto a flat board to get a number of
aggregates that you can use for this assessment. Use a spade
to help you break open the cube if needed.
Source: Hardwick 2014 Step 4: Repeat with 10
aggregates at 20cm depth.
Scoring Root Volume
Now you have assessed the Root Volume of your sample score it using the table below. Don't
forget to assess root volume at 2 depths; 10cm and 20cm:
10cm depth
Rating Poor Moderate Good Very Good
Description
0-3 out of 10 4-6 out of 10 7-9 out of ten 10 out of 10
Score 0 1 2 3
20cm depth
Rating Poor Moderate Good Very Good
Description Nil 1-3 out of 10 4-8 out of 10 More than 8
Score 0 1 2 3
Now write the scores for each assessment onto your RASH Score Card
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Soil Organisms
What is it:
As well as micro-organisms such as fungi, bacteria and protozoa, a healthy topsoil should
contain a diverse range of larger organisms such as earthworms, spring-tails, ants,
nematodes, mites, pot-worms, millipedes, dung beetles and a range of other insects.
Many of these are visible to the naked eye. These larger organisms are called soil
organisms.
Why they are important:
Soil organisms are important to soil health in a number of ways. Many of them are
important in helping breakdown organic matter and the cycling of nutrients through the
process called mineralisation. Others such as earthworms and dung beetles also have a
positive influence on soil structure and water infiltration. Although some soil organisms
feed on living plant roots and are pathogens, most do not. In fact many soil organisms
are predators of pathogens and can keep their populations under control.
How to assess it:
Soil organism diversity can be assessed by visually counting the number of different
types (the diversity) of organisms seen in a soil sample over a period of time. Taking an
intact soil cube slice off the top 5cm, break this sample in half and spread one half out
on a flat board or plastic tray so it is evenly spread out. Then observe the sample for
5mins using a stopwatch or timer. Make a note of each different type of organism seen.
Equipment List
From the Kit:
Magnifying Glass or Hand Lens, Plastic Trays, Stopwatch, Soil Organism ID Sheet, Pen,
Scorecard
Additional:
Fresh water
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Assessing Soil Organisms
Step 1: Place a cube on a Step 2: Carefully slice the top Step 3: Now place this sample
sheet. 5cm of the cube off. Then cut this onto a tray & spread it out.
in half.
Time yourself and spend 5 minutes looking for soil
organisms such as worms, larvae, ants, mites, spiders,
centipedes and beetles in the sample. These have been
attracted by the roots, microbes and organic matter.
Also look for pores in the soil that have been created
by either roots or soil organisms. A hand lens or
magnifying glass is handy for this exercise.
Use the RASH Soil Organism ID Guide to help you.
Not only are numbers of organisms important but so is
having a diversity of organisms present. Record the
Step 4: Allow your eyes to adjust for 1 minute number of different types of organisms you see.
and then start looking for organisms. Count the Don't forget to record your observation on your score
number of different types of organisms you see. card.
Use the Soil Organism Id Guide in the Kit to
help you.
Scoring Soil Organisms
Now you have assessed the Soil Organism diversity of your sample score it using the table
below:
Rating Poor Moderate Good Very Good
Description Nil seen 1 type only 2-5 types seen More than 5 types
seen
Score 0 1 2 3
Write the score for each assessment on your RASH Score Card
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RASH Score Card
To complete a RASH you need to record your assessments so you can evaluate them
against a benchmark and see if your soil is reasonably healthy or you need to take
management action to improve it. Use the RASH Score Card to do this. Copies of these
can be found in the RASH Kit or are available from Little River Landcare Inc. or Soil Land
Food.
Completing the RASH Score Card
Step 1
The top of the Score Card has a section where you can fill the general
details on the monitoring including date, seasonal conditions,
your property, paddock names along with an ID for your monitoring point.
Date: Property Name: Paddock:
Transect Id: GPS/Location
Description
Seasonal Days since 20mm Soil Texture
Conditions rain From your texture assessment:
Step 2
Step 3 After you have done your Texture test then fill
in the soil texture box on the top of the Score Card.
As you complete each of the
Soil Health assessments you can Score the results.
Indicator Comments Rating Results Av. Score
Poor Moderate Good Very Good 1 2 3 4 5
0 1 2 3
Groundcover Use the Less than Between 50% Between 70% Over 90%
Groundcover 50% & 70% & 90%
Worksheet
Infiltration More than 10 3 to 10 mins Less than 3 Less than 1 min
mins mins but more
than 1 min
Step 4 Step 5
Now fill the in score for each sample site Add up and average your 5 sample scores
If scores are less than 2 then use the
Troubleshooting Guide to look at
options for improvement.
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Troubleshooting Guide
If you Score Poor or Moderate on any of the Soil Health Indicators then there is an
opportunity to improve your soil by implementing management practices that can
improve Soil Health. Use the Table below to identify possible management practices for
addressing any low soil health conditions with your soil.
Indicator Situation Possible Causes Management Options
Groundcover Low levels of Overgrazing, poor plant Strategic grazing, ripping, fertilisers or
surface litter or growth, herbicides, soil amendments, use shade tolerant plants,
plants compaction, erosion, stubble retention, conservation tillage
shading, excessive tillage
Infiltration Poor infiltration Soil sealing, low ground Ripping, reduced tillage methods, cover
due to poor cover levels, crusting, crops, green manures, controlled traffic,
surface structure compaction, poor structure pasture phase, strategic grazing
Aggregate Aggregates Low soil organic matter, Use reduced tillage, cover crops, green
Stability collapse sandy texture, manures, use of pasture phase, organic
amendments like manure/compost, strategic
grazing
Sodicity Aggregates High levels of exchangeable Apply Gypsum, increase organic matter
disperse sodium levels by cover crops, green manures, use
of pasture phase, organic amendments like
stubble, manure/compost, mulches
pH Acidic soil Inherent soil factors, Add lime or dolomite, change nitrogen
excessive nitrogen fertiliser use, increase organic matter as
fertilisers, low soil organic above
matter
pH Alkaline soil Inherent soil factors, low Add sulphur products, increase organic
soil organic matter matter as above
Salinity High levels of Rising water table, saline Use pasture phase to lower water table, use
soil salinity irrigation water, high salt tolerant species, change fertiliser use,
salt-based fertiliser use shandy irrigation water, match crop to land
potential
Root Depth Shallow rooting Compaction, poor pH or Ripping, address chemical constraints as
depth salinity, chemical toxicity, above, diverse crop rotations, add more
soil borne diseases, low organic matter as above
fertility
Root Volume Low volume of Compaction, poor pH or Ripping, address chemical constraints as
roots in topsoil salinity, chemical toxicity, above, diverse crop rotations, add more
soil borne diseases, low organic matter as above
fertility
Soil Organisms Low diversity of Lack of habitat/structure, Use strategic grazing, increase organic
organisms low soil organic matter, low matter levels by cover crops, green
Groundcover levels manures, use of a pasture phase, organic
amendments like stubble &
manure/compost, reduce tillage, minimise
chemical use, strategic grazing
Source: SoilCare 2007, Ausveg 2007, NSW DPI 2007, Pattison, Moody & Bagshaw 2010, BRG CMA 2011.
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References & Acknowledgements
References:
Ausveg & Land & Water Australia (2007). Healthy soils for sustainable vegetable farms: Ute Guide. Ausveg &
Land & Water Australia, Australia.
Border Rivers-Gwydir Catchment Management Authority (2011). Ground Truths Uncovered: Managing
Groundcover for erosion control and productive pastures. Border Rivers-Gwydir Catchment Management
Authority, NSW.
Department of Natural Resources & Water (2007). Constraints to cropping soils in the northern grains region –
A decision tree. Department of Natural Resources & Water, QLD.
Gugino, Idowu, Schindelbeck, van Es et al (2009). Cornell Soil Assessment Training Manual 2nd Ed. Cornell
University, College of Agriculture & Life Sciences, New York.
Hardwick (2014). Assessing Topsoil Health – Fact Sheet. Soil Land Food, NSW.
Mackinnon, Scott & Evans (2003). Soil Fertility Management in Low Rainfall Farming Systems of Central
Western NSW. NSW Agriculture, NSW.
Murray Catchment Management Authority. Soil Health Monitoring Kit Manual. Murray Catchment
Management Authority, NSW.
NSW Department of Primary Industries (2007). Salinity Glove Box Guide NSW Lachlan & Macquarie
Catchments – 1st Edition. NSW Dept of Primary Industries, NSW
Pattison, Moody & Bagshaw (2010). Soil Health for vegetable production in Australia. Department of
Employment, Economic Development and Innovation, QLD.
Pattison & Lindsay (2006). Banana root & soil health users manual. Department of Primary Industries and
Fisheries, QLD.
SoilCare Inc. (2007). Northern Rivers Soil Health Card. SoilCare Inc. NSW.
USDA (2001). Soil Quality Test Kit Guide. US Department of Agriculture. USA.
This extension publication was written by David Hardwick, Soil Land Food. The Landcare RASH Kit & Manual was
developed as part of the “Thinking Topsoil Project 2014” delivered by the Little River Landcare Group Inc., NSW. The
project and this publication was supported by Little River Landcare Group Inc., NSW. Funding from the Australian
Government’s Caring for our Country program and the Central West Local Land Services is greatly acknowledged.
The input & feedback from Central West, Watershed & Central Tablelands NSW Landcare members and landholders in the
South East Local Land Services Soil Health Groups 2012-2013, who participated in field days and “paddock tested” the
various RASH activities is gratefully acknowledged. Thanks to Derek Smith, TAFE New England, for assisting with many
of the photographs and his input. Thanks to Thea Ridley from Watershed Landcare for assisting with earlier soil health
projects where the root assessment activities were developed. Additional support from participants in the “Digging
Deeper” Soil Extension project, Terrain NRM, Nth Qld is acknowledged.
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