Soil Test Note – No. ST004
Dr. Stanley L. Chapman, Extension Soils Specialist
DIAGNOSTIC SOIL AND
PLANT SAMPLING INSTRUCTIONS
Soil Sampling
Definition: Diagnostic
soil samples are those taken to solve a fertility problem or provide background
and follow-up data. (Examples: total and/or ammonium-N, boron, cation exchange
capacity, organic matter, soluble salts, chloride.)
Where
to send: Send all diagnostic soil samples to the Marianna laboratory along
with clear instructions about the tests desired. Mark “Diagnostic Sample” on the shipping label and use the “Soil
and Plant Diagnostic Information Sheet, CES-423”, a copy of which is included
in the Diagnostic Testing Service Handbook.
Make checks payable to the University of Arkansas Diagnostic Lab. The basic diagnostic test will be run at Marianna.
The samples will then be forwarded to Fayetteville if additional tests
are desired.
For
a currently growing crop: Collect plant samples as well as soil samples
from both the “affected” and “unaffected” area. In taking plant samples, follow “Plant Sampling
Instructions” noted later in this sheet. These samples should be considered as diagnostic samples. SEND SOIL SAMPLES TO THE MARIANNA LABORATORY.
For Collecting Background Data
Soil Sampling Instructions
1.
Row Crops:
-
Send separate soil samples from the
affected and unaffected areas.
-
In each area, take one sample from
the row and another from between the rows.
-
If only one sample from each location
is taken, sample the 0-6”.
-
If two depths per location are taken,
sample the 0-6” and 6-12” layers.
-
If salts are suspected problem, sample
in 3” increments down to 12 inches.
2.
Pasture and Sod Crops:
(Remove thatch before sampling.)
-
Take separate soil samples from the
affected and unaffected areas.
-
If only one sample from each area:
0-4”.
-
If two samples from each area: 0-3”
and 3-6”.
-
For deep-rooted crops like alfalfa,
take a 6-12” sample in addition to one or two from above.
-
If nitrates are suspected high, sample
0-4”, 4-8” and consider deeper samples to detect problems with high levels
in subsoil.
3.
Rice: (The following sampling depths are preferred
over those in the first draft specifications in the Diagnostic Testing Service
Handbook.)
-
Take samples from both the affected
and unaffected areas.
-
If only one sample from each area:
0-1”
-
If two samples from each area: 0-1”,
0-2”
-
If three depths are taken, sample the
0-1”, 1-2”, and 2-4” layers.
4.
Horticultural Crops:
-
Remove surface mulch before sampling
soil.
-
Sample as for rows crops, form affected
and unaffected areas.
NOTE: Beginning in
1993, the Marianna Soil Testing Lab began routine testing for nitrate-nitrogen
on all soil samples. There will be
no charge for diagnostic analyses provided the request is for the county agents’
use and the soil sample information form has been marked as diagnostic with
a red “D” above the column headings “Sample 1” or “Sample 2”, etc., and just
below the line for city, state and zip code.
Write “troubleshoot” on the top of the form and sign your name. Otherwise, a fee of $8.00 per sample will be
required from the farmer.
Plant Sampling
Definition: Plant samples
provide information on the mineral content of plant tissue (leaves, stems,
petioles, etc.). Plant nutrient monitoring
programs are available for cotton, wheat, corn, grain sorghum, and orchard
crops. Special instructions apply
to these programs.
Where
to send: Mail or ship diagnostic plant samples to: Agri Diagnostic Lab, 276-A Altheimer Drive,
Fayetteville, AR 72704. Make checks
payable to University of Arkansas Diagnostic Lab. Use fee schedule in EL 558 or check with county Extension office
for current prices.
Plant Sampling Instructions
1.
Agronomic or Horticultural Crops
A.
Do Not Sample!
1.
Dead or obviously diseased,
insect damaged or mechanically injured plants.
2.
Plants with dust or soil-covered
leaves.
3.
Plants which have had no rainfall
since the last foliar application of insecticides, fungicides, or other chemicals
including foliar fertilizer.
B.
Select same plant parts from
the normal and problem areas if both are to be sampled. If sampling instructions are not given for
crop, a general rule is to sample the most recently fully matured leaf. If grass type plant (pastures, small grains,
rice, lawns) select top leaf or above ground whole plant. If salt injury is suspected, collect separate
leaf samples from upper and lower parts of the plant; especially for chloride
toxicity in soybeans.
C.
Drying and Packaging Wet or
Green Samples:
1.
Free samples of surface moisture
(dew or rain) before placing in paper bag.
2.
Air dry samples before mailing
if time allows before mailing. Microwave
drying for 10 to 20 second pulses on medium setting may also speed drying.
Caution: Avoid microwaving on high to avoid combustion.
2.
Forest Crop
A.
Hardwood:
Leaf
samples should be taken from the mid to upper crown and from a terminal branch
position which is exposed to direct sunlight at least half of the day. Optimum sampling dates are from August 15 to
September 15.
B.
Pine:
1.
Collect samples in December
through March from the same plant position as for hardwoods.
2.
Take needles only from the first
flush from the previous growing season on the primary lateral branch.
3.
The sample should consist of
about a handful of needles.
May,
1995
The Arkansas Cooperative Extension Service offers its programs
to all eligible persons regardless of race, color, national origin, religion,
gender, age, disability, marital or veteran status, or any other legally protected
status, and is an Equal Opportunity Employer.