Soil health and land use

  • Image, Soil health and land use.

    Different land uses put pressure on the land environment and can result in changes to soil health. Healthy soil supports the productivity of agriculture and forestry, and filters water to help prevent waterways from becoming contaminated. Soils are considered healthy if they fall within the target ranges for the indicators of acidity, fertility, organic reserves, and physical status.

    We classified Soil health and land use as a case study.

    Key findings

    In surveys that were conducted from 2009–13, more than 80 percent of soil health tests were within the target range for their respective land use.

    • All forestry and cropping/horticulture tests were within their target range for acidity.
    • Cropping/horticulture had the highest percentage (90 percent) of tests within targets for organic reserves.
    • Only 39 percent of dry stock sites and 23 percent of dairy sites were within their target range for physical status.
    • Between the first (1995–2008) and second (2009–13) survey periods, the proportion of sites within their target range for physical status decreased from 59 percent to 41 percent.

    Figure 1

    Note: Data from Landcare Research; regional councils of Northland, Waikato, Bay of Plenty, Taranaki, Hawke’s Bay, Manawatu-Wanganui, Wellington, Canterbury, Otago; district councils of Marlborough and Tasman; Nelson City Council; Auckland Council.

    Figure 2

    Note: Some sites did not have a recorded value for all tests. Soil sites with missing tests were excluded from the analysis. Data from Landcare Research; regional councils of Northland, Waikato, Bay of Plenty, Taranaki, Hawke’s Bay, Manawatu-Wanganui, Wellington, Canterbury, Otago; district councils of Marlborough and Tasman; Auckland Council.

    Figure 3

    Note: Some sites did not have a recorded value for all tests. Soil sites with missing tests were excluded from the analysis. Data from Landcare Research; regional councils of Northland, Waikato, Bay of Plenty, Taranaki, Hawkes Bay, Manawatu-Wanganui, Wellington, Canterbury, Otago; district councils of Marlborough and Tasman; Auckland Council.

    Figure 4

    Note: Sites were resurveyed at approximately equal intervals over a range of dates from 1995-2008 and 2009-13. Data from Landcare Research; regional councils of Northland, Waikato, Taranaki, Wellington, Caterbury; district councils of Marlborough and Tasman; Auckland council.

    Definition and methodology

    Soil health is informed by seven tests. These tests are classified into four indicators:

    • acidity (measured by soil pH)
    • organic reserves (measured by total carbon, total nitrogen, and mineralisable nitrogen)
    • fertility (measured by Olsen phosphorus)
    • physical status (measured by bulk density and macroporosity).

    The data comes from nine regional councils, surveyed at 419 soil sites down to 100mm deep. Of these soil sites, 323 were re-surveyed between the first (1995–2008) and second (2009–13) survey periods. These survey sites represent around 90 percent of the area in each agricultural activity. The regions surveyed include Northland, Auckland, Waikato, Taranaki, Hawke’s Bay, Wellington, Tasman, Marlborough, and Canterbury (Mackay et al, 2013).

    The target ranges for each measure are derived from Sparling (2007). To be within the target range for an indicator, the site had to meet target ranges for all contributing tests.

    Data quality

    We classified Soil health and land use as a case study.

    Relevance

    relevance-partial This case study is a partial measure of the ‘Soil health and quality’ topic.

    Accuracy

    accuracy-high The accuracy of the data source is of high quality.

    See Data quality information for more detail.

    References

    Mackay, A, Dominati, E, & Taylor, MD (2013). Soil quality indicators: The next generation. Client report number: RE500/2012/025. AgResearch, Palmerston North. Available from www.envirolink.govt.nz.

    Sparling, G (2007) Land: Soil quality assessed from the 500 Soils Project Environment New Zealand 2007. Unpublished, prepared for the Ministry for the Environment. Wellington.

     

    Updated 21 April 2017

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