A damning report released by the Ministry of the Environment and Stats NZ last month says that New Zealand’s land use is contributing directly to soil and water degradation, soil erosion and is reducing the health and diversity of our plants, animals and habitats.
The report, Our Land 2018, shows more than 48 per cent of tested sites were outside the target range for two key indicators of soil quality. These were phosphorous content (an indicator of soil fertility) and macroporosity (a measure of soil compactness).
Excess phosphorous can travel into waterways through erosion and run off. It can trigger growth of unwanted plants and reduce water quality.
Soil that is too compacted restricts plant growth and reduces soil diversity. It also impedes soil drainage, resulting in increased greenhouse gas emissions from urine on soils and an increased amount of phosphorous and eroded soils reaching waterways.
The report says sites under more intensive land uses, such as dairying, cropping, horticulture and dry stock, were more frequently outside the range for these soil quality indicators.
In particular, 51 per cent of tested dairy sites had excess soil phosphorus and 65 per cent were below the range for macroporosity.
Some horticultural and cropping sites also had high phosphorous levels (37 per cent) and low macroporosity levels (39 per cent). Dry stock sites had low macroporosity levels (41 per cent).
The report says New Zealand already has naturally high rates of erosion due to a combination of steep terrain, rock and soil types and climate. New Zealand contributes about 1.7 per cent to global sediment loss, even though it makes up only 0.2 per cent of global land area.
The report says the problem is exacerbated by the removal of trees. New Zealand loses 192 million tonnes of soil each year from erosion and 44 per cent of this comes from pasture land.
The report’s findings come as no surprise to Ahuroa sheep and beef farmer Bev Trowbridge, who has long advocated for “regenerative farming” practices, which aim to protect the soil.
She says farmers are often extremely concerned about soil degradation but says pressure from banks, suppliers, market buyers and industry representatives all conspire to reinforce destructive farming practices.
“Farmers do not get to choose to go it alone, to market their own produce, or change to a high-value, low impact model. This is the travesty of our farming system,” she says.
Ms Trowbridge says the irony is that the solutions to the problems are not difficult. For example, farmers could make greater use of natural, organic fertilizers, especially compost, which has an abundance of living creatures within it that break up compacted soil.
Meanwhile, the report itself declines to make recommendations on how to redress problems with land use, but it says it is vital that New Zealand pays attention to the harm it is doing to the soil, noting that the quality of the soil underpins the New Zealand economy.
“This report provides an opportunity for us to recognise that soil and biodiversity are taonga (treasure), that our stewardship depends on earnestly building our knowledge base, and that it is our responsibility to take action to restore the health of the whenua (land), for today and tomorrow’s generations,” it says.