Changes in soil quality and land use in grazed pasture within rural Auckland
2013
Curran Cournane, F | Fraser, S. | Hicks, D. | Houlbrooke, D | Cox, N
As part of state-of-environment reporting, soil quality monitoring in Auckland has indicated that decreasing macroporosity is a concern for grazed pasture. This prompted a more intensive study undertaken in 2011 to resample the original 35 sites. Comparisons were made between Soil Orders and land uses, with soil samples taken from all repeat sites and under adjacent/ungrazed fence-lines to act as a control. Macroporosity was significantly less for grazed/tread (7%) than ungrazed/control (15%) treatments. However, macroporosity in the control treatment was only just within recommended guidelines for the Ultic Soil Order, representing >40% of Auckland's soils. The study found that what were originally described as two land use categories; dairy and drystock, increased to four categories; dairy, dairy-drystock conversion, drystock, and lifestyle conversion. Although 83% of dairy sites occupied what would be considered prime land, a large proportion of prime land was also occupied by lifestyle sites (64%), followed by dairy-drystock (38%) and drystock (30%). Such information raises two concerns: first, that a large proportion of prime land is not being used for commercial primary production; and second, the difficulty in developing soil quality trends as a result of land use changes.
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