Research Branch Report No. 258

Nutrient loss from broadcast burning of eucalypt debris in North-east Victoria.  H.T.L. Stewart and D.W. Flinn.  September 1984.  15 pp.  (unpubl.)


Eucalypt forest in an experimental catchment was cleared, and the debris broadcast burnt. The debris had a biomass of 26.73 kg m-2 and a nutrient content similar to that of other eucalypt forests of similar productivity. The moderate to high-intensity fire consumed 50% of all debris, and significantly increased pH, organic carbon, extractable phosphorus and exchangeable potassium and calcium in the 0-2 cm soil layer. Extractable phosphorus also increased in the 2-4 cm soil layer.

Quantities of total nitrogen and phosphorus, and exchangeable potassium, calcium and magnesium in the surface 20 cm of soil, and the total quantities of these nutrients in the debris were estimated before and after burning. Losses of nutrients as a proportion of the quantities estimated in the surface soil and debris were 1.7% and 6.5% of the total phosphorus and nitrogen respectively and 17.2%, 19.9% and 32.8% of the exchangeable potassium, magnesium and calcium respectively. Because tree roots explore profile depths considerably below 20 cm and because the relationship between the labile pool of site nutrients and those estimates made of losses due to burning is not known, it is not possible from the data available to estimate the effects of such losses on site productivity.

Also published:

Stewart, H.T.L. and Flinn, D.W. (1985)  Nutrient losses from broadcast-burning of eucalyptus debris in north-east Victoria.  Aust. For. Res. 15: 321-332.