Lawn & Tree Care

16-4-5, 50%SRN Magnesium, Sulfur & Micronutrients

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Deep Root Feed! Premium Liquid Fertilizer for Trees & Ornamentals

P.F.C.’s 16-4-5, 50% SRN has been formulated for deep root feeding of trees and ornamentals. It supplies the primary nutrients of Nitrogen, Phosphorus and Potassium plus Magnesium, Sulfur, Boron, Copper, Iron, Manganese and Zinc all in one ready-to-use package. Being a liquid, 16-4-5, 50% SRN mixes instantly with water that makes it a natural to use with hydraulic equipment. A substantial percentage of the Nitrogen in 16-4-5, 50% SRN is unique as it is derived from Triazone. With Triazone, there is little chance of burn because it makes its Nitrogen available through a slow, regulated breakdown of complex molecules. Triazone lasts substantially longer than Urea or Ammonium Nitrate in the soil and provides a steady source of Nitrogen to trees and ornamentals. 


Directions for Use:

Deep Root Feeding: To feed with your hydraulic system at the 1 pound per caliper inch rate, obtain a hydraulic needle probe unit with an on/off lever. To determine the output of your equipment, place the probe in a bucket and time how long it takes to pump one gallon of water. The time it takes to fill one gallon is the amount of time you will require for each one-gallon injection. Apply five such one-gallon injections per caliper inch of tree, totaling five gallons of diluted solution. The rate of 1 pound per caliper inch of tree is obtained by mixing 100 pounds (10 gallons) of 16-4-5, 50% into 500 gallons of water and injecting five gallons of diluted solution per caliper inch of tree. To determine the caliper inches of a tree, measure the diameter of the tree at breast height. The fertilizer injections should be made 21⁄2 feet apart beginning two feet from the trunk of the tree going in a circular pattern around the tree extending two feet beyond the drip line. Make sure the injection probe penetrates into the soil to your desired feeding depth, which should be 8 to 12 inches deep. Care should be taken to prevent hollowing out of the root area with excessive water. 

Gallons H2O Gallons 16-4-5 Pounds 16-4-5 Caliper Inches of Tree
5 1/10 1 1
500 10 100 100
1000 20 200 200


The Most Commonly Used Rate: One pound of 16-4-5, 50% SRN per each caliper inch of tree provides:

  • .16 lb. of Nitrogen
  • .04 lb. of Phosphorus
  • .05 lb. of Potassium

Simplified Tree & Ornamental Feeding: For deep root feeding mix 1 to 5 gallons of 16-4-5, 50% SRN per 100 gallons of water. Inject 1 to 5 gallons of the diluted fertilizer solution per each inch of tree trunk diameter at breast height. 16-4-5, 50% SRN will provide a continuous feeding throughout the growing season.

Foliar Feeding: Mix 2 to 3 quarts of 16-4-5, 50% SRN per 100 gallons of water; spray until light run-off. Foliar feeding with 16-4-5, 50% SRN will help correct deficiencies that occur through the growing season. Do not foliar feed when temperatures exceed 80°F, or in drought conditions.

Turf Feeding with P.F.C.’s 16-4-5, 50% SRN: Know the capabilities and limitations of the applicator you plan to use. Study the area to be treated and calculate the square footage accurately. A rate of 1/2 pound Nitrogen per 1,000 sq. ft. is accomplished by applying:

  • 21⁄2 pints per 1,000 sq. ft.
  • 1 gallon per 3,200 sq. ft.
  • 5 gallons per 16,000 sq. ft.

Add the proper amount of water to obtain this coverage. (Two to five gallons of water per 1,000 sq. ft.). The 1/2 pound rate should be used during warmer weather or when watering is not practical. Avoid application during periods of extremely hot or dry weather. The 1 pound rate should be used in spring and fall during colder weather, or where complete irrigation or watering may be accomplished after application.