Research Branch Report No. 129

Soluble nutrient inputs in rain and outputs in stream water during 1977 for small forested catchments in North-eastern Victoria.  D. W. Flinn, L. J. Bren and P. Hopmans.  April 1979.  55 pp. (unpubl.)

SUMMARY

Weekly inputs of soluble nutrients in bulk precipitation and outputs in stream water for three small, forested catchments near Myrtleford in north-east Victoria are being measured, and this paper discusses results for 1977. Results showed that accretion of dissolved Na, K, Ca, Mg, Cl, N (as NO-), and P (as PO43-) to the ecosystems in bulk precipitation was low due to the catchments being isolated from both oceanic and industrial influences. Rain water had a pH of between 5.7 and 7.3 according to the season, which was consistent with low atmospheric pollution. Nutrient losses in stream water were also found to be very low, possibly because streamflow represented only 7 - 14% of the total rainfall for the three catchments.

Nutrient balances, taken as the difference between soluble nutrient input in bulk precipitation and output in stream water with no allowances for losses through deep-seepage and other pathways, were positive for all elements studied except Mg where the balance was negative for two out of the three catchments. Respective inputs, outputs (range), and balances (range) in kg ha-1 for 1977 were: Na 2.775, 1.212 to 2.712, +0.063 to +1.563; K 1.818, 0.350 to 0.546, +1.271 to +1.468; Ca 3.253, 0.235 to 1.095, +2.158 to +3.018; Mg 1.103, 0.703 to 2.024, -0.921 to +0.400; Cl 12.446, 1.933 to 3.412, +9.034 to +10.513; P 0.009, 0.002 to 0.007, +0.002 to +0.007; N 0.319, 0.011 to 0.013, +0.306 to +0. 308.

The data supplemented by additional sampling will provide a basis upon which to judge the effects of converting dry sclerophyll native forest in north-east Victoria to Pinus radiata plantations on nutrient balance, water quality and water yield.

Also published:

Flinn, D.W., Bren, L.J. and Hopmans, P. (1979)  Soluble nutrient inputs from rain and outputs in stream water from small forested catchments.  Aust. For. 42 (1): 39-49.

Bren. L.J., Flinn, D.W., Hopmans, P. and Leitch, C.J. (1979) The hydrology of small forested catchments in North-eastern Victoria. I. Establishment of the Cropper Creek Project.  For. Comm. Vic., Bull. 27, 48 pp.