Grass Cure Calculation

Grass Cure Calculation

Determining the amount of curing (dryness) of grasses is a difficult process, but necessary to achieve the most realistic results for grassland fire behaviour indexes.

It is recommended that observers study the grasslands in their climatic zone at close quarters at a number of individual sites.
Determine the overall colour of the grassland and check for seed head development. Match these with the appropriate description in the guide below and select the "percentage cured" figure.
Ensure that the selected figure is appropriate to other grassland species within the district by carrying out observations at a number of other locations.
The "percentage cured" may now be used in the FWI Calc model.

Table : Various Stages of Curing (Barber 1966)

% Cured	Colour	Physiological Change
0	Green	From the beginning of growth to commencement of seed head development
10	Green	Seed heads formed and flowering
20	Yellowish-Green	Seed heads maturing and seed dropping
30	Yellowish-Green	Most seed heads mature and seed dropping
40	Yellow-Green	Most seed heads mature and seed dropping
50-60	Straw - odd patch of green and greenish-yellow	Up to ½ of all stems have dropped their seed, some areas may be fully cured, others may be quite green
70-80	Straw - very little green showing anywhere	Most seed heads have dropped their seed, lower third of stalk may be green
90	Straw - odd green gully	Essentially all seed has dropped, odd individual stalk may be green
100	Bleached	All stalks fully cured, seed heads and stalks break easily