Guide for Producing Nursery Crops
Third Edition


Appendix A



Laboratories registered with the Soil and Plant Analysis Council (Anon. 1999) are listed below. 




Soil Testing Laboratory

ALFA Agricultural Services & Research Building

961 S. Donahue Drive

Auburn University, AL 36849-5411

334.844.3958, FAX: 334.844.4001




Agricultural Diagnostic Laboratory

276-A Altheimer Dr.

University of Arkansas

Fayetteville, AR  72704

501.575.3911, FAX: 501.575.3896


Eastern Arkansas Soil Testing and Research Laboratory

P.O. Drawer 767

Hwy 1 South 3 miles

Marianna, AR 72360

870.295.2851, FAX: 870.295.2432




Agro Services International, Inc.

205 E. Michigan Ave.

Orange City, FL 32763

904.775.6601, FAX: 904.775.9890


Pioneer Laboratory

4100 Glades Road

Ft. Pierce, FL  34981

407.464.9300, FAX: 407.464.9308




Agricultural and Environmental Services


2400 College Station Road

Athens, GA  30607

706.542.5350, FAX: 706.369.5734


Micro-Macro International, Inc.

183 Paradise Blvd., Suite 108

Athens, GA  30607

706.548.4557, FAX: 706.548.4891

Waters Agricultural Laboratories, Inc.

P. O. Box 382

Camilla, GA  31730-0382

912.336.7216, FAX: 912.336.7967




Commonwealth Technologies, Inc.

2520 Regency Rd

Lexington, KY 40503

606.276.3506, FAX: 606.278.5665


University of Kentucky Soil Testing Laboratory

103 Regulatory Services Building

Lexington, KY  40546-0275

606.257.7355, FAX: 606.257.7351




LSU Agricultural Center Plant Analysis Laboratory

Agronomy Department

Louisiana State University

Baton Rouge, LA 70803

504.388.1305, FAX: 504. 388.1403




University of Missouri Soil and Plant Testing


23 Munford Hall

University of Missouri

Columbia, MO  65211

573.882.3250, FAX: 573.884.4288


North Carolina


NC Department of Agriculture

Agronomic Division

4300 Reedy Creek Rd.

Raleigh, NC  27607

919.733.2655, FAX: 919.733.2837




Soil, Water and Forage Analytical Laboratory

048 Agricultural Hall

Oklahoma State University

Stillwater, OK 74078

405.744.9572, FAX: 405.744.9575


South Carolina


Agricultural Service Laboratory

171 Old Cherry Rd

Clemson, SC 29634

864.656.2068, FAX: 864.656.2069



A&L Analytical Laboratories, Inc.

411 North Third Street

Memphis, TN  38105

901.527.2780, FAX: 901.526.1031




Texas Agricultural Extension Service Soil, Water, and Forage Testing Laboratory

345 Heep Center

College Station, TX 77843-2474

409.875.4816, FAX: 409.845.5958


Texas Plant & Soil Laboratory, Inc.

Route 7, Box 213-y

Edinburg, TX  78539

956.383.0739, FAX: 956.383.0730




Virginia Tech Soil Testing and Plant Analysis Laboratory

145 Smyth Hall

Blacksburg, VA  24061

540.231.6893, FAX: 540.231.9262


West Virginia


West Virginia University Soil Testing Laboratory

Division of Plant and Soil Science

P. O. Box 6108

Morgantown, WV 26504

304.293.6256, FAX: 304.293.2960

Appendix B


Substrate Physical Properties


Bulk Density

Bulk density is expressed as dry weight per volume of container (conversions are g·cm-3 x 62.43 = lbs/ft3 or lbs/ft3 x 0.02 = g·cm-3). To determine dry bulk density, contents of the container are dried until they no longer lose weight. This may be accomplished by placing container with substrate in an oven at 158 F for 48 hours.


Air Space and Water-Holding Capacity


Procedure conducted with same containers used in plant production

The following procedure, taken from Diagnostic and Monitoring Procedures for Nursery Crops  (D.L. Ingram, et al., 1990), can be used to determine substrate air space and total water holding capacity as a percentage of container volume.


Air space of a substrate is the total volume of pores filled with air after irrigation and drainage. The water-holding capacity is the percentage of the total volume of the substrate that is filled with water after irrigation and drainage. When a substrate is saturated and allowed to drain, air replaces the volume of water drained. Measuring the drainage water then gives a measurement of pore space or air space. Steps in the procedure for determining air space and water-holding capacity are given below. If a measurement of air space alone is desired, there is no need to determine the volume of water required to saturate the dry substrate in step 3.

  1. Measure the container volume. Secure tape on the container drainage holes and fill with water to within approximately 0.5 inch from the top. Mark this line. Carefully measure the volume of water by pouring it into a measuring cup. This volume of water is the container volume to be occupied by the substrate. An alternative way to determine container volume is to place a plastic bag in container and fill with water to desired volume.
  2.  Dry the container inside. Do not remove the tape. Fill the container with dry substrate to the “fill line,” marked in Step 1, using packing procedures as when potting a plant.
  3.  Using a measuring cup, slowly add water to the container and keep track of the volume of water used. Wet the dry substrate until it is saturated (a thin film of free water is present on the surface). Some dry substrates such as peat or pine bark are difficult to wet. If a wetting agent is used in production, then use a wetting agent at this time at the recommended rate. Add small amounts of water periodically as necessary to ensure complete saturation. The volume of water used to saturate the substrate is the total pore space of the substrate.
  4.  Loosen the tape on one drainage hole and discard water that drains from the substrate. This initial drainage helps settle the substrate, as occurs in production.
  5.  Cover the drainage hole and re-saturate the substrate with water. Adding water along only one side of the container will minimize air pockets.
  6.  Place the container in a pan or bucket large enough to collect all drainage water. Elevate the container above the pan for complete drainage. Remove the tape from the holes and collect the water drained during two hours.
  7.  Measure the volume of water drained from the container. Use the smallest units on the measuring cup (milliliters, ounces, or teaspoons).
  8.  Calculate the percent air space and water-holding capacity by the formulas below.
  9.  It is advisable to test three to five container/substrate samples at the same time and average the results.

         % Air space = Volume of drained water (Step 7)

                                                                                   x 100

                                   Container volume (Step 1)


         % Total Water-holding capacity = Total pore space (Step 3) – Vol. drained water (Step 7)

                                                                                                                                              x 100

                                                                                 Container volume (Step 1)

A plant cannot extract the total volume of water from the container substrate. Unavailable water is the portion of total water-holding capacity the plant is not able to take up.  The portion of water-holding capacity volume taken up by the plant is called available water.  The amount of available water in the container substrate can be determined by wetting thoroughly the substrate in a container with plant, so the substrate is holding all the water possible against the drainage force of gravity. Enclose container in plastic bag, weigh the container and plant. Let dry and weigh again just prior to plant beginning to wilt. The difference in wet and dry weight is water available to the plant or water taken up by the plant. Total water-holding capacity minus available water leaves unavailable water.


Procedure conducted with simulated containers

The following procedure adopted from the Australian Standard 3743 - Potting Mixes (Standards Australia, 1989) can be used to determine substrate air space and total water-holding capacity as a percentage of container volume. A plant cannot take up the total water-holding capacity volume as discussed above. 

  1. Glue a PVC cap to a length of 3-inch diameter PVC pipe so height of pipe and cap is equal to depth of substrate in container, then determine the total volume inside of assembly (cap and pipe). Flatten the cap with appropriate tool so the assembly will stand upright. Drill four 0.25-inch holes in the bottom of the cap, with one in the center.  Place a 3-inch diameter PVC coupling with 4.5-inch long pipe extension, loosely, on top of assembly and fill assembly and pipe extension with moist substrate. Drop the assembly twice from three inches.  Refill after the second drop but do not pack.
  2. Place the assembly in water so that the top of the coupling is at the surface of the water. Three hours later, remove from water, drain, and submerge for ten minutes; lift, drain, and submerge for ten minutes. Remove from water and remove coupling with pipe extension, cutting substrate horizontally at surface of pipe attached to cap. 
  3. Cover substrate with a cloth held in place with a rubber band.
  4. Submerge again, and after 30 minutes, lift the assembly with fingers covering the holes in the cap. Let excess water drain from your hands, then place the assembly above a pan for at least ten minutes to allow drainage.  Measure volume drained. 


5. Divide drainage volume by total volume of the assembly to calculate the percent aeration.


% Air Space  =  Volume of drained water (ML)

Assembly volume (ML)


6. Weigh wet substrate, dry in forced air oven at 221 F, and weigh again. The difference in wet and dry substrate    weight (grams), divided by total volume (milliliters) of assembly is the percent total water-holding capacity.


% Total Water-holding capacity = Wet weight – Dry weight (g)

Assembly volume (ml)


7. It is advisable to test three to five assembly/substrate samples at the same time and average the results.


Appendix C


Substrate Nutrition


Pour-through (PT) - Procedure for Sampling


This procedure is practical for containers with volumes of five gallons or less because larger containers are too heavy to lift. The PT enables rapid sample collection without removing substrate from individual containers or groups of small containers that form cavities in trays.


  1. Irrigate plants and allow time for drainage (two hours to overnight) and equilibrium of moisture and nutrients within the substrate. Uniform substrate moisture levels are critical to obtaining consistent results with time.
  2. After this equilibration period, the container must be elevated above a collection vessel so that leachate or extract is not contaminated with debris or salts on the perimeter of the container. The bottom or sides of the container or flat should not be wiped before collecting leachate.
  3. Using a circular motion, apply just enough distilled water or irrigation water to the substrate surface to yield 30-50 ml (1.0-2.0 oz) of leachate (liquid) from the container or flat. See Table 13for approximate volumes to apply.
  4. Filter the leachate samples before sending to a commercial laboratory.



Table 13. Approximate volume of water to apply to obtain 50 ml (2.0 oz.) of extract with PT.

Container size

Water to apply



4 to 6 inch container



6.5 azalea container



1 quart



1 gallon



3 gallons



5 gallons



Cavities or cells in flats



Containers should be at container capacity for about 30 minutes (for cavities or cells in flats and small containers) to 2 hours (for larger containers) before applying water. The volumes of water are estimates so actual amount may vary depending on crop, substrate, or environmental conditions. (Adapted from 1, 2, 3 of PourThru, Whipker et al. 2001).

Suction Lysimeter (SL) - Procedure for Sampling

This procedure enables rapid sample collection without removing substrate from large containers (greater than five-gallon) or physically moving containers. Lysimeters are about 24 inches long and two inches in diameter with a porous ceramic cup (0.5 bar air entry) on the end.

  1. A lysimeter is positioned about two inches from the container side and remains in place during crop production. To insert the lysimeter into the container substrate, a hole is made in the substrate slightly smaller than the lysimeter diameter so that the lysimeter fits snug within the substrate.
  2. One to two hours after irrigation, a vacuum pump is used to create a vacuum within the lysimeter tube. After about 15 minutes, the vacuum results in liquid extracted from the substrate collecting in the lysimeter tube.
  3. Remove the extract from the lysimeter using a syringe fitted with an extension tube. Once the extract is removed from the lysimeter, nutrient analyses can be conducted. Lysimeters (model 1900 L24) and accessories may be obtained from Soil Moisture Equipment Company, Santa Barbara, CA 03105 (

Saturated Substrate Extract (SSE) - Procedure for Sampling

  1. Using a soil sample probe or a pointed object such as a spatula, remove substrate from each of 5-20 containers representative of the crop or plants under consideration.
  2. The upper layer of substrate cores may be disturbed and should be discarded. Blend the cores together into one uniform sample.
  3. Save about 200 ml (0.5 pint) of the total sample for saturation.
  4. Slowly add distilled water while stirring until the substrate surface is shiny, but no free water moves across the surface when the beaker is tilted. For best equilibration, allow the saturated sample to sit for two to six hours.
  5. Extract the substrate solution by vacuum filtering the saturated substrate.

Field Soils - Procedure for Sampling

In order for the soil sample to be representative of the field or area under consideration, several small samples are collected throughout the field or area, carefully mixed, and a sub-sample of the mixture is sent to a laboratory.

  1. A digging implement is used to obtain a small amount of soil from 10-15 locations throughout the field or area under consideration. The soil is removed from the upper 6-8 inches and sampling locations are spaced throughout the field or area.
  2. Each small amount of soil is placed in a plastic bucket. Avoid including soil from any “problem” spots. Submit soil samples from problem spots as separate samples.
  3. After sampling, mix the soil in the bucket so that all the soil is well blended.
  4. Take about a one-pint sub-sample of the blended soil and place it on a shopping bag or newspaper to air dry. Return the remaining soil in the bucket to the field.
  5. When the soil is air dry, transfer the soil to a labeled paper bag and send to a laboratory.

Calculating the Amount of Nutrients Applied


Fertilizer Purchases

Records of the fertilizer purchased yearly were used to calculate the amount of fertilizer applied, assuming all the fertilizer purchased was applied.


Suppose a nursery bought 2500 lbs of 18-6-12 and the production area of this nursery is 9.0 acres. In 2500 lbs of 18-6-12 there are 450 lbs of nitrogen, which were distributed on 9.0 acres during the year, resulting in 50 lbs of nitrogen per acre.


Fertilizer Applications

The amount of fertilizer applied with each application is summed to obtain total applied or to account for all the fertilizer applied throughout the year. For example, a nursery made three fertilizer applications during the year (Table 14). The first application consisted of 1000 lbs of 19-6-12 applied to containers in a field of 2.0 acres.

The second application consisted of 1650 lbs of 14-14-14 applied to containers in a field of 2.5 acres. The third application consisted of 1000 lbs of 18-6-12 applied to containers in a field of 7.5 acres. Therefore, 600 lbs of nitrogen were applied to 12.0 acres, resulting in 50 lbs of nitrogen applied per acre.


Trade names, companies, and products are used for informational purposes and do not constitute endorsement or recommendation nor discrimination for similar products not mentioned.

Table 14.  Total amount of nitrogen from three applications.

Time of Application

Fertilizer Applied (lbs.)


Nitrogen applied (lbs)

Area (acres)