Publication Date

1993

Location

New Zealand

Description

A multidisciplinary study was undertaken to investigate the changes in catchment runoff, groundwater recharge and soil fertility after the complete removal of brigalow (Acacia harpophylla) forest for buffet grass pasture. Clearing brlgalow for pasture increased runoff amount by 21 mm/year; however, runoff represented a·· small (11-14%) component of the annual water balance. An increase in groundwater recharge immediately after clearing was not sustained once the pasture was established. Clearing did not alter the annual water balance, evapotranspiration taking 90% of annual rainfall, Clearing and burning• caused a flush of plant available N, P and K but this was short-lived,; )Vithin 3 years, soil organic C and soil total N levels had returned to' pre-clearing levels. Five years of grazed pasture removed an estimated IO kg N/ha, and was considerably less exploitive of soil N thin cereal cropping (212 kg N/ha).

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Water Balance and Soil Fertility Characteristics of Brigalow (Acacia harpophylla) Lands Before and After Forest Clearing

New Zealand

A multidisciplinary study was undertaken to investigate the changes in catchment runoff, groundwater recharge and soil fertility after the complete removal of brigalow (Acacia harpophylla) forest for buffet grass pasture. Clearing brlgalow for pasture increased runoff amount by 21 mm/year; however, runoff represented a·· small (11-14%) component of the annual water balance. An increase in groundwater recharge immediately after clearing was not sustained once the pasture was established. Clearing did not alter the annual water balance, evapotranspiration taking 90% of annual rainfall, Clearing and burning• caused a flush of plant available N, P and K but this was short-lived,; )Vithin 3 years, soil organic C and soil total N levels had returned to' pre-clearing levels. Five years of grazed pasture removed an estimated IO kg N/ha, and was considerably less exploitive of soil N thin cereal cropping (212 kg N/ha).