GNF Management Table, November 21, 2014

This GNF Management Table forms part of the GNF Management Protocol. These are the instructions for the determination of NUs reasonably expected in the GNF generated at the greenhouse operation as required for registration and the preparation of a GNF strategy submitted at the time of registration under O. Reg. 300/14 made under the Nutrient Management Act, 2002.

  • The GNF Management Table (Table) below provides two methods:
  1. Method 1 - Use this method if generation of GNF is expected from one of the listed greenhouse crops and if the portion of leachate not reused in the closed circulation system is between 3.13 per cent and 50 per cent inclusive.
    1. Choose the line in the Table most representative of the crop and the portion of leachate not reused in the closed circulation system. If your operation falls in between two values in the column entitled "Portion of Leachate not Reused in Closed Circulation System (GNF)" you must use the higher value. Use this line to determine the values in items C. and D. below.
    2. Determine the greenhouse production area in ha for this crop and circulation system
    3. To obtain the volume of GNF generated in a calendar year, multiply greenhouse production area by the value found in the column 'Volume of GNF Generated in a Calendar Year Per Unit Area of Greenhouse Crop Production'
    4. To obtain the number of nutrient units of GNF generated in a calendar year, multiply greenhouse production area by the value found in the column 'Number of Nutrient Units in GNF Generated in a Calendar Year Per Unit Area of Greenhouse Crop Production'
  2. Method 2 - Use this method only if the crop grown is not listed in method 1 or if the portion of leachate not reused in the closed circulation system is less than 3.13 per cent or greater than 50 per cent.
    1. Determine the volume (m3) of GNF that you estimate could be generated by a greenhouse in a calendar year
    2. To obtain the number of nutrient units in GNF generated in a calendar year, multiply the estimated volume of GNF generated in a calendar year by the value found in the column 'Nutrient Units per Volume of Expected GNF Generation in a Calendar Year'
  • Using either method as appropriate, repeat this process for all GNF expected to be generated at each greenhouse operation on the farm unit and add the NUs for each greenhouse operation.
  • Add the NUs for all greenhouse operations on the farm unit to determine the number of nutrient units in the GNF generated on the farm unit in a calendar year.
Method 1
Greenhouse Crop Type Annual Volume of Nutrient Solution Applied to Plant Root Zone i Portion of Applied Nutrient Solution Leaving Plant Root Zone leachate)ii Portion of Leachate not Reused in Closed Circulation System (GNF) Volume of GNF Generated in a Calendar Year Per Unit Area of Greenhouse Crop Production Estimated Plant Available Nitrogen (PAN) Estimated Plant Available Phosphate (PAP) as P2O5 Number of Nutrient Units in GNF Generated in a Calendar Year Per Unit Area of Greenhouse Crop Production
  L/m2 (per cent) % (per cent) % m3/ha mg/L mg/L NU/ha
Tomato 1000 25 50 1250 328.3 231.3 9.5
Tomato 1000 25 25 620 328.3 231.3 4.8
Tomato 1000 25 12.5 310 328.3 231.3 2.4
Tomato 1000 25 6.25 160 328.3 231.3 1.2
Tomato 1000 25 3.13 80 328.3 231.3 0.6
Pepper 1000 25 50 1250 232.3 191.0 6.8
Pepper 1000 25 25 620 232.3 191.0 3.4
Pepper 1000 25 12.5 310 232.3 191.0 1.7
Pepper 1000 25 6.25 160 232.3 191.0 0.8
Pepper 1000 25 3.13 80 232.3 191.0 0.4
Cucumber 1000 25 50 1250 244.3 169.5 7.1
Cucumber 1000 25 25 620 244.3 169.5 3.6
Cucumber 1000 25 12.5 310 244.3 169.5 1.8
Cucumber 1000 25 6.25 160 244.3 169.5 0.9
Cucumber 1000 25 3.13 80 244.3 169.5 0.4
Flower 800 25 50 1000 193.0 92.1 4.5
Flower 800 25 25 500 193.0 92.1 2.2
Flower 800 25 12.5 250 193.0 92.1 1.1
Flower 800 25 6.25 120 193.0 92.1 0.6
Flower 800 25 3.13 60 193.0 92.1 0.3

Method 2
Description Nutrient Units per Volume of Expected GNF Generation in a Calendar Year NU/m3
Any other crop 0.0077
Any greenhouse if, under normal operating circumstances, the portion of leachate not reused in the closed circulation system is less than 3.13 per cent.td> 0.0077
Any greenhouse if, under normal operating circumstances, the portion of leachate not reused in the closed circulation system is greater than 50 per cent. 0.0077

i These are standard values for greenhouse crop production areas in Ontario.

ii These are standard values for greenhouse crop production in Ontario.


For more information:
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Author: OMAFRA Staff
Creation Date: 28 July 2015
Last Reviewed: 28 July 2015