10.1. Determination of percentage of crop residue

For the purpose of subsection 3(4) of the Regulation, the method for determining the percentage of land covered by crop residue is as follows:

Rope transect method:

  • The material required is a light rope (about 8 m in length with knots or other markings spaced along the rope at 15 cm intervals so that there is a total of 50 knots. This rope is laid out across the soil surface, preferably at an angle to the crop rows, and pulled slightly taut. The number of knots that are touching pieces of crop residue (the crop residue being touched has to have minimum dimensions of 2 mm by 2.5 cm) is counted. This number, when multiplied by two, is the per cent crop residue cover. This determination must be made a minimum of four times in different parts of the GNF application area, and the results averaged.

10.2. Procedures for determining unsaturated soil conditions

For the purpose of the definition of "unsaturated soil" in subsection 3(1) of the Regulation, use the following test to determine whether or not the soil has a water content that is less than 100 per cent of the total pore space or is at a negative soil water pressure:

  • dig a hole or remove a soil core to the minimum required depth for the purposes of the Regulation; and
  • observe whether water flows into the hole from the surrounding soil (this may take up to 30 minutes for most hydrologic soil groups but up to 60 minutes for hydrologic group D soils.

10.3. Maximum 24-hour application rate

The following sets out the procedure that must be used to determine the 24-hour maximum application rate referred to in paragraph 2 of subsection 39(1) of the Regulation. This 24-hour maximum application rate must be determined using a soil moisture instrument (e.g. tensiometer) to determine the actual per cent water by volume that is representative of the areas of the field to which GNF is applied. The user must then determine the maximum application rate by calculating the difference between the actual per cent water by volume and the field capacity for this soil texture for the GNF application area as determined using the Soil Moisture Field Capacity Table below. This number is then multiplied by 30.

Calculation: (Field Capacity value from the Soil Moisture Field Capacity Table (Table 2 below) - measured moisture value) x 30 cm x 100 m3/cm per ha = application rate in m3/ha/24 hour period.

Note: the 100 factor is used to convert cm to m and translate to a hectare basis (i.e. 0.01 m/cm * 10,000 m2/ha = 100 m3/cm per ha)


If the actual measured water content of a sandy loam soil is 10%:

The available capacity is calculated as: (0.25 - 0.10) x 30 cm x 100 m3/cm/ha = 450 m3/ha

And the maximum 24-hour application rate in this case would be 250 m3/ha due to the upper limit referred to in section 39 of the regulation.

Table 2. Volumetric soil moisture content at field Capacity (%) for the purpose of the Regulation

Sand, Loamy sand17
Sandy loam, Loam25
Silt loam, Sandy clay loam, Clay loam32
Silt, Silty clay, Silty clay loam, Clay37