Conversion Tables, Formulas and Suggested Guidelines for Horticultural Use
	Bodie V. Pennisi, Gary L. Wade, Melvin P. Garber, Paul A. Thomas and James T. Midcap, Horticulture Department Originally prepared by S.C. Myers and A.J. Lewis, Extension Horticulturists

PDF

Contents

Tables

1. Equivalents for liquid measure (volume)
2. Metric system conversion table
3. Dilution of liquid pesticides at various concentrations
4. Equivalent quantities of dry materials (wettable powders) for various quantities of water based on recommended pounds per 100 gallons
5. Equivalent quantities of liquid materials (emulsion concentrates, etc.) for various quantities of water based on pints per 100 gallons
6. Rate of application equivalent table
7. Fertilizer conversions for specified square feet and row areas
8. Fertilizer weight as measured by standard pot size
9. Element concentrations for pounds soluble fertilizer in 1000 gallons (U.S.) water
10. Number of pots per bushel and per cubic yard of soil mix
11. Coverage estimates for perlite, peat, topsoil and straw
12. Plant spacing guide (greenhouse)
13. Plant spacing guide (field/orchard)

Formulas for calculating greenhouse volume

• Uneven-span greenhouses
• Quonset structures
• Even-span greenhouses

Pesticide and fertilizer recommendations are often made on a pounds per acre and tons per acre basis. While these may be applicable to field production of many crops, orchardists, nurserymen and greenhouse operators often must convert these recommendations to smaller areas, such as row feet, square feet, or even per tree or per pot. Thus pints, cups, ounces, tablespoons and teaspoons are the common units of measure. The conversion is frequently complicated by metric units of measure. This publication is designed to aid growers in making these calculations and conversions, and also provides other data useful in the management, planning and operation of horticultural enterprises.

Table 1. Equivalents for liquid measure (volume)

Table 2. Metric system conversion table

Table 3. Dilution of liquid pesticides at various concentrations

Example: Directions call for a 1:200 dilution. To prepare 3 gal of finished product, you would need to add ¼ cup.

Table 4. Equivalent quantities of dry materials (wettable powders) for various quantities of water based on recommended pounds per 100 gallons

Example: Directions for use specify a rate of 4 lb per 100 gal. water. To prepare 1 gal of solution would require 4 tsp of material

Table 5. Equivalent quantities of liquid materials (emulsion concentrates, etc.) for various quantities of water based on pints per 100 gallons

Example: Directions for use specify a rate of 4 pt per 100 gal water. To prepare 5 gal of solution would require 3 fl oz material.

Table 6. Rate of application equivalent table

Examples: For liquid materials, 100 gal per acre is equivalent to 2¹/3 gal per 1000 ft² or 1 qt per 100 ft². For dry materials, 4 lb per acre is equivalent to 3 tbs per 1000 ft² or 1 tsp per 100 ft².

Table 7. Fertilizer conversions for specified square feet and row area

*High Rates, not desirable in row fertilization, are omitted in the table.

Example: You wish to apply calcium nitrate at the rate of 500 lbs per acre. It weighs approximately 19 oz per pt. for applications to 100 ft², you need 1.2 lb or 1.0 pt.

Table 8. Fertilizer weight as measured by standard pot size

Clay flower pots are frequently used for fertilizer measurement by greenhouse operators. The above shows average weights of several representative fertilizers as measured by standard clay pots when level full. The 3-inch standard is considered to contain 8 fl oz, or one cup. Since the actual pot size varies with the manufacturer and the volume of a given weight of fertilizer varies with moisture and compaction, deviations of 10 percent may be expected but up to 40 percent may occur.

Table 9. Element concentrations for pounds soluble fertilizer in 1000 gal (U.S.) water

Example: You wish to apply 200 ppm N using a 20-10-20 soluble fertilizer. Reading across from 200 ppm under the 20 percent N column, you find 8.4 lb are needed for 1000 gal water.

NOTES: 1 oz/2 gal is about 30 lb/1000 gal; 1 oz/3 gal is about 20 lb/1000 gal; 1 oz/5 gal is about 12 lb/1000 gal. 1 oz/gal = 7490 ppm; 1 oz/100 gal = 75 ppm.

To determine Parts Per Million (ppm) of an element in a fertilizer, simply multiply the percent of that element by 75. The answer will be the ppm of the element per oz of the fertilizer in 100 gal of water. As an example, Ammonium Sulfate contains approximately 20 percent Nitrogen. 20 percent multiplied by 75 is 15, which is the ppm of Nitrogen in 1 oz of Ammonium Sulfate per 100 gal of water.

Table 10. Number of pots per bushel and per cubic yard of soil mix

NOTE: Based on volume of pots when filled level to rim with loose, unpacked soil mix.

Table 11. Coverage estimates for perlite, peat, topsoil and straw

*1 cubic yard (yd³) = 27 cubic feet (ft³)

Table 12. Plant spacing guide (greenhouse)

*Assuming ^1/3 of production area devoted to aisles, etc.

Table 13. Plant spacing guide (field/orchard)*

*To determine the number of plants per acre for spacings not given in the table, multiply the distance in the row by the distance between rows and divide that number into 43,560.

Formulas for calculating greenhouse volume

For the following formulas:

L = length
W = width
W₁ = width of short span
W₂ = width of long span
H_e = height from floor to eave
H_r = height from eave to top

Uneven-span greenhouses

Quonset structures

Even-span greenhouses

Acknowledgements

The authors wish to acknowledge the following sources, certain tables from which were adapted to use in this publication.

• Cornell Recommendations for Commercial Floricultural Crops, Part 1. Cultural Practices and Production Programs.
• Nutrition of Greenhouse Crops. Cooperative Extension Services of the Northeast States.
• Tons to Teaspoons, L2285. University of California Cooperative Extension Service.