Table 1. Expected range of values for soilless
media parameters analyzed according to SME
procedure (Warncke 2011)
Parameter
Range
Nutrient
Balance '
pH
5. 0-6.5
—
EC2
<300 mhosx 10'5/cm
—
EC
< 3 mS/cm
—
IN-N
40-200 ppm
—
NO.-N
40-200 ppm
8-10%
NH.-N
4
0-20 ppm
<3%
P
5-20 ppm
К
30-300 ppm
11-13%
Ca
20-250 ppm
14-16%
Mg
15-150 ppm
4-6%
Na
—
<10%
Cl
—
<10%
1 Nutrient balance =
[nutrient concentration (ppm) x 100] EC (ppm)
EC (ppm) = EC mhos x 10'5/cm x 7.0
or
EC (ppm) = mS/cm x 700
2 The NCDA&CS Agronomic Division measures
EC in units of mhosx 10'Vcm.
Additional resources
Warncke D. 2011. Recommended test
procedures for greenhouse growth media.
In: Sims JT, Wolf A, editors. Recommended
soil testing procedures for the northeastern
United States. Newark (DE): Univ Del
Agric Exp Station. Northeastern Regional
Bulletin 493. p 103-10.
Whipker B. 1998. Submission procedures for
root substrate, water, fertilizer solution and
plant tissue samples. Raleigh (NC): NC State
Univ Dept Hort Sci & NC Coop Ext Serv.
Horticulture Information Leaflet 560.
North Carolina
Department of Agriculture
and Consumer Services
Steve Troxler, Commissioner of Agriculture
Agronomic Division
Colleen M. Hudak-Wise, Ph.D., Director
Plant/Waste/Solution/Media Section
Brenda Cleveland, Agronomist
www.ncaar.aov/aaronomi/
(919) 733-2655
Mailing Address
1 040 Mail Service Center
Raleigh NC 27699-1040
Physical Address [DHL, FedEx, UPS]
4300 Reedy Creek Road
Raleigh NC 27607-6465
For more information on
sampling, interpreting agronomic reports or
implementing recommendations ,
contact the regional agronomist
assigned to your county.
www.ncaqr.qov/aqronomi/rahome.htm
Agronomic Sampling
Folder No. 9
April 2014
Soilless Media
Analysis: Sampling,
Results & Rationale
Floriculture, Nursery & Greenhouse Crops
Soilless media are light-weight substrates used
in containerized production of floriculture
and nursery crops, greenhouse vegetable and
tobacco transplants. Common components of
soilless substrates include compost, peat moss,
perlite, pine bark, sand and/or vermiculite.
Unlike mineral soils, soilless substrates tend to
have little capacity to supply or retain nutrients
or to buffer pH. Consequently, container
nutrient levels and pH are dynamic. Regular
monitoring of pH, electrical conductivity and
nutrient levels makes it possible to fine-tune
fertilization programs and keep them on track.
Saturated media extract (SME) procedure is
used by the Agronomic Division for soilless
media analysis. It is preferred over traditional
soil testing for laboratory analysis of container
substrates (Warncke 1998). The Division
offers the SME procedure through its Plant,
Waste, Solution and Media laboratory.
Methods and measures
SME measures electrical conductivity (EC),
nitrate-nitrogen (NO,-N), ammonium-nitrogen
(NH4-N), phosphorus (P), potassium (K),
calcium (Ca), magnesium (Mg), sulfur (S),
sodium (Na) and chloride (Cl ). EC units are
mhosx 1 0'5/cm,andnutrientconcentrationunits
are parts per million (ppm). pH is measured
on a 1:1 sample-to-water (by volume) slurry.