1. Assessing the Pasture Soil Resource A Publication of
ATTRANational Sustainable Agriculture Information Service
1-800-346-9140 www.attra.ncat.orgBy Preston Sullivan This technical
note provides methods to determineNCAT Agriculture biological
activity of pasture soils and practical tipsSpecialist on improving
the usefulness of typical soil andPublished 2001 plant samples. The
soil biology sampling methodsUpdated April 2010 are easy to learn
and utilize commonly availableBy Hannah Sharp tools found around
any farm. Once these biologi-NCAT Intern cal assessments are made,
more insight into the NCAT many benets of nutrient cycling becomes
appar- ent. Methods for strategically using soil and plant samples
are also covered.ContentsMaking fertilityassessments
.................... 1Assessing soil biological
Introductionactivity and health ........ 2When to make these Making
fertility assessments Aassessments .................... 2 typical
soil analysis will provide aEquipment needed ...... 3 guide to the
current plant nutrientLocating sample sites ... 3 levels in a
pasture soil. For an analysisPoints of assessment .... 3 to be
accurate, good sampling procedure must Photo by Susan Tallman,
NCAT. 1) Living organisms .... 3 be followed. Before sampling a
pasture soil: 2) Earthworms .............. 3 1. Visit the county
Cooperative Exten- ridge tops and will be glad you sampled 3) Soil
smell ................... 4 sion Oce and get their guide on soil
top, side and end slopes separately. 4) Aggregation ............. 4
sampling procedure. 5) Water inltration .... 4 5. Make sure that
sampling depth matches the 6) Soil compaction ..... 4 2. Look
across the landscape and locate all depth that the soil test report
will be based hotspots. Hotspots are areas of excessive on. Many
agronomists advise taking pastureConclusion
........................ 5 or unusual nutrient concentration, such
samples at 3 or 4 inches deep because mostReferences
........................ 6 as soils around feed bunks, hay feeding
of the grass roots are in the top 4 inches.Further resources
........... 6 areas, shade trees, watering sites, loang The
prescribed depth should be in the soilAssessment sheet ......... 7
areas and wet spots. sampling procedure from your Cooperative
Extension Oce. If you do take a sample at 3. Sample these hotspots
separately, or avoid a depth other than the one the lab species,
them during your sampling. make note of it on your sample sheet so
the 4. Sample according to apparent patterns lab can adjust
accordingly. such as slope and previous fertilization. 6. Prepare
the sample for shipping according When eld areas appear dissimilar,
sam- to the labs recommendations.ATTRANational
SustainableAgriculture Information Service ple them separately.
Nutrients tend to(www.attra.ncat.org) is managed ow downhill in
pastures, meaning that Producers generally have the choice of
usingby the National Center for Appro-priate Technology (NCAT) and
is top slopes will tend to have lower nutri- a private laboratory
or the state universityfunded under a grant from the ent levels and
the down slope will tend lab to do their soil analysis. Commercial
labsUnited States Department ofAgricultures Rural Business- to have
higher levels. Mixing soil samples cost more but generally have a
quicker turn-Cooperative Service. Visit the from all over the
pasture will mask these around time and a more complete soil
testNCAT website (www.ncat.org/sarc_current.php) for dierences and
lead to wasted fertilizer report than university labs. Though
hotlymore information on dollars. When it comes time to buy fer-
contested by some researchers, soil analysisour sustainable
agri-culture projects. tilizer, you may only need to fertilize the
featuring the base saturation percentages
2. provides useful information for making fer- tilizer choices.
If you would like to get a sec- Table 3. Soil test analysis between
a ond opinion, it may be worthwhile to hire poor area and good area
of a pasture a consultant to help you with the sampling Nutrient
Poor area Good area and the fertilizer recommendations. Nitrogen To
back up your fertilization program you Phosphorus OK OK may want to
take forage samples to see what Potassium low OK eect the
fertilizer had. You can also stra- Calcium OK OK tegically utilize
soil and forage tissue sam- pling by making comparisons between
Magnesium OK OK poor growth areas and good growth areas, Sulfur OK
OK or before-and-after comparisons. The three tables below show
some hypothetical examples of strategic soil and plant tissue
sampling. Assessing soil biological Forage analysis can be used to
judge the activity and health success of a fertilization program by
iden- While nutrient status is essential to soil tifying any
remaining nutrient decits. For health and vitality, biological
activity andRelated ATTRApublications example, the before-and-after
forage analy- soil structure should be appraised to get a sis shown
in Table 1 shows that the applied more complete picture. The
biological soilNutrient Cycling component creates and maintains
many fertilizer met all crop needs for major andin Pastures
secondary nutrients. In addition, soil and desirable soil
conditions. Many biologicalA Brief Overview forage analysis taken
from adjacent poor parameters are quite costly to measure andof
Nutrient Cycling and productive eld areas can be used to require
hours of laboratory time. Others canin Pastures better identify
nutrient imbalances. Th is be quite inexpensive and convenient.
TheSustainable Soil is illustrated in Tables 2 and 3. Visit your
following assessment procedures can be per-Management county
extension agent or a private consult- formed in an hour or so using
inexpensive, ant to learn eective methods for taking a locally
available materials (Holistic Man- forage sample. agement
International, 2007). These proce- dures are derived from Holistic
Management Table 1. Forage tissue analysis before Biological
Monitoring Manual available from and after fertilization Holistic
Management International. For a Nutrient Before fert. After fert.
more complete cropland assessment, order Nitrogen low OK this
publication. Ordering information is Phosphorus OK OK listed in the
Further resources section. Potassium low OK Calcium OK OK When to
make these assessments Choose a time of year when soil biological
Magnesium OK OK activity is high, usually in late spring Sulfur low
OK and mid-fall. Select a day when the soil is moist but not wet,
after all excess water has Table 2. Forage tissue analysis between
drained away. Generally, the soil is right a poor area and a good
area for this assessment when you cannot roll Nutrient Poor area
Good area the soil into a ball and it crumbles easily in Nitrogen
low OK your hand. Phosphorus OK OK Avoid taking samples: Potassium
low OK From wet soils. When the soil sticks Calcium OK OK to your
shoes, it is too wet. Magnesium OK OK During drought periods or
times of Sulfur low OK excessive heat.Page 2 ATTRA Assessing the
Pasture Soil Resource
3. From cold soils. Begin by selecting the rst point for evalu-
Within a month following tillage, ation at the sampling site and
lay the 1-foot fertilization or liming. diameter ring on the
ground. The following assessments are most conveniently done by
completing all six at the rst point beforeEquipment needed moving
on to the second point. Pencil Assessment sheet Points of
assessment Clipboard to hold the paper 1) Living organisms Shovel
Clip all the standing vegetation within the Can or jar capable of
holding 16 wire circle down to the ground and remove uid ounces (1
pint) but no more it. Pull back the soil surface litter and look
for Small round bottle capable of holding signs of living organisms
other than plants. cup of water A small hand rake may help in
turning the surface litter. Count the number of dierent Bucket with
2 gallons of water for kinds of living critters, such as beetles,
ants, I each assessment sheet to be lled out millipedes,
centipedes, snails and more, on f a pasture is Watch with a second
hand or the soil surface within the ring. Record the highly
variable, a stopwatch numbers on the assessment sheet. assess each
Tape measure It is advisable to start turning the surface distinct
area Hand grass clippers litter from the outside of the ring toward
separately. In each the center. This forces mobile critters to
pasture unit, three Homemade soil penetrometer, the center where
they will be seen by the described below sampling sites observer.
If you start at the center and work should be selected. A wire ring
that measures 1 foot toward the ring, the critters have a chance to
across, made of wire or exible pipe escape outside the ring
undetected. With this assessment the number of species, or diver-
Note: The length of wire required to make sity, is more important
than the number of a circle with a 1-foot diameter is approxi-
individuals. mately 39 inches, depending on the thick- ness of the
wire. Remember to allow some A higher number of dierent types of
organ- extra length to attach the two ends and isms indicates more
biodiversity. The more make the ring. Measure the diameter of
biodiversity, the better the first stage of the wire ring when the
ends are attached decomposition will proceed. to make sure it is 1
foot across. 2) EarthwormsLocating sample sites While still at the
circle, count the numberAn individual assessment sheet should be of
wormholes inside the ring. The surfaceused for each pasture. If a
pasture is highly holes are the vertical burrows of
nightcrawlervariable, assess each distinct area separately. worms.
After counting the wormholes, insertIn each pasture unit, three
sampling sites the shovel to its maximum depth and turnshould be
selected. Use eld maps, com- over the shovelful of soil. Break the
soil apartpasses, landmarks or global positioning sys- with your
hands and count the number oftems to locate representative sample
sites earthworms present. The smaller wormsthat can be relocated
year after year. These found with the shovel will most likely
besites become permanent locations for assess- the surface-dweller
earthworms that do noting change over time. Each eld site can be
burrow vertically.marked on a map to aid relocation. At each Record
the numbers on the assessmentsampling site, choose two points to
take the sheet. Also note how easy or dicult it wasactual
assessment. to shovel the soil. Turning a shovelful
ofwww.attra.ncat.org ATTRA Page 3
4. soil also correlates well with tilth and ease indicated here
by a high score. Unstable of tillage. The more earthworms found in
aggregates break apart easily and the this process, the better.
Earthworm burrows individual soil particles can be easily eroded by
enhance water inltration and soil aeration. runo water. Higher
scores are generally more Earthworm digestion of soil and organic
common under perennial sod. Lower scores are matter cycles
nutrients. Worms are a general generally more common on soils with
annual indicator of soil health. Earthworms may not tillage
operations and clean cultivation. be present in croplands recently
converted to Move away from the wire circle to a fresh pasture.
They should slowly return over sev- area. Clip a small area of
grass to ground level eral years from adjacent eld margins as soil
if necessary to see the soil surface clearly. Fill health improves.
a 1-pint container with water. Holding the container as close to
the soil surface as pos- 3) Soil smell sible, gently pour the water
on the soil. Try While still at the hole dug for worm counts, to
pour all the water out within ve seconds, grab a handful of topsoil
and take a whi. the idea being to avoid disrupting the soil Record
the smell on the assessment sheet as surface with the water ow, but
pouring fast follows: enough to determine how quickly the waterA
well- soaks into the ground. Using the stopwatch, aggregated 0.0 =
putrid/chemical/sour start timing once all the water has been soil
will take 0.2 = no smell poured out. Stop timing when the last of
thein water rapidly, as water just nishes soaking into the ground.
0.4 = fresh/earthy/sweetwill a soil with high This is the
inltration time to be recordednumbers of vertical on the assessment
sheet. 4) Aggregationwormholes. Next, measure the wet spot across
its widest Select a soil aggregate, or crumb, from a hand- point
with the tape measure and record the ful of topsoil. Make sure the
aggregate is not length on the assessment sheet. Pouring on a a
rock or pebble. Put the aggregate in the small slope will inuence
the rate of runo. If you round bottle of water or the 1-pint
container. are comparing two cropping practices on Allow it to
stand for one minute, using the sloping ground, make sure the slope
is the stopwatch to keep time. Observe if the aggre- same under
both practices since slope will gate is breaking apart or staying
intact. If it inuence the runo rate. stays intact after one minute,
gently swirl the bottle several times and observe again. If it is
still intact, swirl the bottle vigorously and 5) Water inf
iltration observe the aggregate again for intactness. The faster
water enters the soil, the less likely Record the following scores:
it is to run o overland and cause erosion. A well-aggregated soil
will take in water rap- 1 = aggregate broke apart within one minute
idly, as will a soil with high numbers of ver- in standing water
tical wormholes. Texture plays a signicant 2 = aggregate remained
intact in standing role in water in ltration. Sandy soils will
water but broke apart after gentle swirling take in water more
quickly than silty-loam soils, and clay soils will take in water
quite 3 = aggregate remained intact after gentle slowly. Finally,
since soil moisture at the time swirling will inuence this
assessment, dont put too 4 = aggregate remained intact after
vigorous much condence in an inltration compari- swirling son
between two elds if one is irrigated and the other is dry. After
vigorous swirling, remove the aggregate and smash it between your
ngers to make sure it was not a pebble. If it was a pebble, 6) Soil
compaction select another aggregate and do the test again.
Assessing soil compaction requires making a Healthy soils have very
stable aggregates, simple tool beforehand. A soil penetrometerPage
4 ATTRA Assessing the Pasture Soil Resource
5. can be constructed from a 1/4-inch rod compaction of the
surface layer, whichsharpened on the end as seen in Figure 1
restricts downward water movementbelow. Start with a rod that is 3
feet long. (Holistic Management International, 2007).Use a le to
make 1-inch marks from thepointed end, as shown in the drawing.
ConclusionPush your homemade penetrometer into the Performing the
soil organism assessmentsoil as deep as you can with modest eort.
described will enhance observational skills,Record the inches of
penetration up to a max- which is always benecial. Some other
use-imum of 12 inches. Do not record any pene- ful observations
include plant vigor, planttration depths beyond 12 inches, as we
are not coloration, drought tolerance and the ratetesting for deep
penetration. Avoid putting at which livestock manure is dispersed
andall your weight into the pushing or stomp- decayed. Healthy soil
conditions are largelying on the penetrometer to make it go deeper.
created by the helpful soil organisms, whichRecord the penetrometer
depth on the assess-ment sheet. If you hit a rock or tree root, try
are benecial with a little management toagain. For comparison,
probe an undisturbed meet their needs.natural area nearby with your
penetrometer. Dont be discouraged if the pasture assess-As a
secondary test, you may wish to probe ment numbers come up lower
than expecteddeeper with a longer penetrometer to locate the rst
time. Rather, let the results be anany deeper hard pans to note on
the comment incentive for continued commitment to soilsection of
the assessment sheet. improvement. Pursue progress rather thanThe
deeper the probe easily penetrates the perfection. An assessment
provides a startingsoil, the better. Ease of soil penetration point
from which to build toward the future.with the penetrometer
correlates to deep Set your sights high. Discard the idea thatroot
development, ease of downward water soils require hundreds of years
to build up.ow, or no hardpan, and tillage ease. A Soils can begin
to improve just a few monthsprobe that wont penetrate the soil
indicates after appropriate decisions are made.Figure 1: Homemade
soil penetrometerwww.attra.ncat.org ATTRA Page 5
6. References Nation, Allan. 1995. Quality Pasture. Mississippi
Valley Publishing, Corp., Jackson, MS. 285 p.Holistic Management
International. Holistic Manage- To order this publication, visit
the Stockman Grassment Biological Monitoring Manual. 2007. 59 p.
Farmer online store at
www.stockmangrassfarmer.http://holisticmanagement.org/store//page4.html
net/cgi-bin/page.cgi?id=364.html or contact Stock- man Grass
Farmer, PO Box 2300, Ridgeland, MSFurther resources 39158-9911,
1-800-748-9808, (601) 853-1861,Anon. 1999. Soil Quality Test Kit
Guide. Soil QualityInstitute. Natural Resources Conservation
Service. (601) 853-8087 FAX, [email protected].
Accessed May 2009. http://soils.usda.gov/sqi/ Tugel, A.J., A.M.
Lewandowski and D.
Happe-vonArb,assessment/les/test_kit_complete.pdf eds. 2000. Soil
Biology Primer. Ankeny, IA: Soil andAnon. 2003. Pastureland Soil
Quality Indicators Water Conservation Society. 48 p.for Assessment
and Monitoring. Natural Resources To order this publication, visit
the Soil and Water Con-Conservation Service. USDA. Accessed May
2009. servation Society online store at
http://store.swcs.org/http://soils.usda.gov/sqi/management/les/PSQIS2.pdf
index.cfm?fuseaction=c_Products.viewProduct&catIEvanylo, Greg
and Robert McGuinn. 2000. D=574&productID=5154Agricultural
Management Practices And SoilQuality. Natural Resources and
Environmental Holistic Management International. Holistic
Manage-Management. Virginia Cooperative Extension. ment Biological
Monitoring Manual. 2007. 59 p.Virginia Tech. Accessed May 2009. To
order this publication, visit the HMI online
storewww.ext.vt.edu/pubs/compost/452-400/452-400.html at
http://holisticmanagement.org/store//page4.htmlFawcett, Richard. No
date. An Introduction to Nutrient or contact Holistic Management
InternationalManagement. Conservation Technology Information
Center. (HMI), 1010 Tijeras, NW, Albuquerque, NMAccessed May 2009.
http://ctic.org/media/pdf/ 87102, (505) 842-5252, (505) 843-7900
FAX,nutrient mgmt primer_1.pdf [email protected] 6
ATTRA Assessing the Pasture Soil Resource
7. Pasture Soil Assessment
SheetProperty________________________ Field _________________ Date
_______ Examiner _________________ Living Soil Earthworm Earth-
Aggrega- Water Water Points organism Soil smell penetra- holes
worms tion inltration inltration types tion species/ circle
#/circle #/shovel scorea scoreb timec distanced inches Site I 1 2
Site II 1 2 Site III 1 2 Totals Average*a smell score = 0
putrid/chemical/sour; 2 no smell; 4 fresh/earthy/sweet; for
in-between smell, use odd numbers 1 or 3.b aggregation score 1 =
broke apart in water after 1 minute; 2 = broke apart after gentle
swirling; 3 = intact after gentle swirling; 4 = intact after
vigorous swirlingc time required for water to inltrate into the
soild distance across wet spot at widest point* divide the total in
each column by 6Supporting Information1. Are there signs of erosion
in this eld? yes ____ no_____2. List the crops and practices done
in this eld in the last 2 years:
__________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________Comments:www.attra.ncat.org
ATTRA Page 7
8. Assessing the Pasture Soil Resource By Preston Sullivan,
NCAT Agriculture Specialist Published 2001 Updated April 2010 by
Hannah Sharp, NCAT Intern NCAT Holly Michels, Editor Amy Smith,
Production This publication is available on the Web at:
www.attra.ncat.org/attra-pub/pastsoil.html or
www.attra.ncat.org/attra-pub/PDF/pastsoil.pdf IP128 Slot 46 Version
042810Page 8 ATTRA