Converting Fertilizer Rates www.LSUAgCenter.com from Tons to Teaspoons Fertilizer recommendations are usually given in pounds per acre and lime in tons per acre. The home gardener, nurseryman and greenhouse grower often have trouble converting the per-acre rates to amounts for small areas, single rows or single potted plants. The most convenient measur- ing tools are pints, cups, tablespoons or teaspoons. The tables here are guides for determining the amounts of various fertilizers to use for different volumes of soil, single potted plants, single rows and small areas. The conversions in the tables are not exact, but they’re accurate enough to help you Some equivalents that may be helpful are: determine the proper amount of fertilizer. The volume of fertilizer to be applied varies 1 acre is equal to 43,560 square feet with different material because of weight differ- 1 pint of water weighs 1 pound ences. For example, granular sodium nitrate weighs about 23 ounces per pint, whereas granular ammo- 1 pint equals 2 cups nium nitrate weighs about 13 ounces per pint. The ratios given here are not intended as rec- 1 pint equals 32 tablespoons ommendations but as conversion guides. For fertil- 1 pint equals 96 teaspoons izer recommendations, consult your county agent. Table 1. Conversions for Flower Pots or Flower Boxes Pounds Volumes of Average Fertilizer Per Acre Flowerpots (see footnote)* Flower Boxes 4-inch 6-inch 8-inch 1 sq. ft. 2 sq. ft. Teaspoons Tablespoons Tablespoons Teaspoons Teaspoons 250 2 ½* 1 ½* 5* ½ 1 500 5* 3* 10* 1 2 750 7 ½* 5* 15* (1 cup) 1 ½ 3 1000 10* 7* 20*(1 1/4 cup) 2 4 *Dissolve 1 teaspoon of fertilizer in a pint of water and add amounts of this mixture given in the table for flowerpots. 1 LSU AgCenter Pub. 1545 Converting Fertilizer Rates from Tons to Teaspoons Table 2. Approximate Volumes of Fertilizer for Small Areas Materials Grouped Use These Weights Use These Volumes Use These Volumes According to Rate Per Specified Area Per Specified Area Per 3’ Rows Approximate Per 100 sq. ft. 1000 sq. ft. 10 sq. ft. 100 sq. ft. 10 ft. 100 ft. Weight Per Unit Acre Pounds Pounds Tbsp. Cups Cups Pints Sulfur, flowers of 100 .2 2.3 1.2 3/4 .2 1 cottonseed meal 300 .7 6.9 3.6 2 .6 3 (10 oz./pt.) 500 1.2 11.5 6.0 4 1.1 5 ½ 1000 2.3 23.0 12.0 7 ½ 2.2 11 Ammonium nitrate 100 .2 2.3 .9 ½ .2 7/8 Urea 300 .7 6.9 2.7 1 3/4 .5 2 ½ (13 oz./pt.) 500 1.2 11.5 4.5 3 .8 4 1000 2.3 23.0 9 5 ½ 1.6 8 Ammonium phosphate 100 .2 2.3 .7 1/3 .1 ½ Mixed fertilizer 300 .7 6.9 2.1 1 ½ .3 1 ½ Potassium chloride 500 1.2 11.5 3.5 2 1/4 .7 3 ½ (16 oz./pt.) 1000 2.3 23.0 7 4 ½ 1.4 7 ½ Ammonium sulfate 100 .2 2.3 .6 1/3 .1 ½ Superphosphate 300 .7 6.9 1.8 2 .3 1 1/4 (19 oz./pt.) 500 1.2 11.5 3 4 .6 3 1000 2.3 23.0 6 8 1.2 6 Nitrate of soda 100 .2 2.3 .5 1/3 .1 ½ Ground limestone 300 .7 6.9 1.5 1 .3 1 1/8 (23 oz./pt.) 500 1.2 11.5 2.5 1 ½ .5 2 ½ 1000 2.3 23.0 5 3 1 5 2000* 4.6 46.0 10 6 ½ 2 10 *Higher rates given for limestone. 2 LSU AgCenter Pub. 1545 Converting Fertilizer Rates from Tons to Teaspoons Table 3. Approximate Volumes of Fertilizer for a Given Volume of Soil Volumes of Fertilizer for These Volumes of Soil Fertilizer Materials Rate Per Cubic Yard Per Cubic Foot or 7 ½ gal. 5 gallons 1 gallon Per Acre Tbsp. Cups Tsp. Tsp. Tsp. Tsp. Mixed fertilizers or 100 4 1/4 ½ 1/3 Potassium chloride or 300 12 3/4 1 1/3 1 Ammonium phosphate 500 20 1 1/4 2 1/4 3/4 1 2/3 1/3 1000 40 2 ½ 4 ½ 1 ½ 3 1/4 3/5 Ammonium nitrate 100 5 1/3 2/3 ½ or Urea 300 15 1 1 ½ ½ 1 1/4 500 25 1 ½ 2 3/4 7/8 2 2/5 1000 50 3 1/8 5 ½ 1 3/4 4 4/5 Ammonium sulfate 100 3 1/3 1/5 2/5 1/4 or Superphosphate 300 10 5/8 1 1/5 3/4 500 16 3/4 1 2 2/3 1 1/4 1/5 1000 33 2/3 2 3 3/4 1 1/4 2 3/4 ½ Nitrate of soda or 100 2 3/4 1/3 1/5 Ground limestone 300 8 ½ ½ 1 1/3 3/4 500 14 7/8 1 ½ ½ 1 1/5 1/4 1000 28 1 3/4 3 1 2 1/5 ½ 2000 56 3 ½ 6 2 4 ½ 1 Sulfur or 100 6 ½ 1/3 4/5 ½ Cottonseed meal 300 19 1 1/4 2 2/3 1 ½ 500 32 2 3 2/3 1 1/4 2 2/3 ½ 1000 64 4 7 1/5 2 1/3 5 1/5 1 Louisiana State University Agricultural Center Revised by William B. Richardson, Chancellor J. Cheston Stevens Louisiana Agricultural Experiment Station (Soil Fertility Management) John S. Russin, Vice Chancellor and Director Louisiana Cooperative Extension Service Paul D. Coreil, Vice Chancellor and Director Author Eddie R. Funderburg www.LSUAgCenter.com Pub. 1545 (Online only) 3/12 Rev. (Soils and Fertilizers) The LSU AgCenter is a statewide campus of the LSU System and provides equal opportunities in programs and employment. 3 LSU AgCenter Pub. 1545 Converting Fertilizer Rates from Tons to Teaspoons.