How do ‘Soils’ fit into the RPS?
Soil provides a number of services fundamental to our prosperity, but is often undervalued. Indeed, we rely on it to support primary industries including farming, forestry and horticulture. Soil enables food production, provides a platform for construction, filters and regulates water and gases, recycles and stores organic matter and nutrients, and maintains healthy habitats and biodiversity.
Our region has a wide range of soils, including some of the most productive in New Zealand. However, subdivision of rural land has increased and concentrations of cadmium (which does not break down and is harmful to humans and the environment) in agricultural soils have been gradually increasing since the use of phosphate fertilisers became widespread in the 1940s.
In addition, some intensive land use practices are causing a reduction in soil quality – damaging its structure, fertility and porosity, and triggering a build-up of contaminants. Some land uses are also resulting in increased nutrients, sediment, pathogens and algal growth in water bodies.
Many of the region’s high class soils are in or around urban areas and are consequently under pressure from urban expansion and infrastructure development. Using high class soils for urban development pushes agricultural activities onto more marginal soils.
The RPS focuses on maintaining and enhancing the life supporting capacity of the soil resource, retaining high class soils, managing peat soils and contaminated land and minimising soil contaminants.
A number of the methods in the RPS are already being implemented. Some new ideas that are being developed include improving and making high class soil information available to other parties, looking at soil contaminants in addition to cadmium, implementing some of the actions identified in the contaminated land strategy and increasing our understanding about how to manage peat soils and the relative impacts of different land uses.
Soil is special: The Waikato region contains about one quarter of New Zealand’s high class soils, making them a significant resource within the region. The RPS encourages a range of methods including preparing and administering soil conservation and catchment management programmes in order to reduce erosion risk. It pushes for research into the risks from and effects of erosion and soil degradation, for education and advice to be given to land managers, and for information on high class soils, including soil classifications, to be available to territorial authorities and other interested parties.
Managing soil to keep it healthy: Soil disturbance and loss results in a decline in soil quality and productive capability, and a loss in the range of purposes for which the soil can be used. Erosion occurs naturally irrespective of land use, but the way that land is managed changes the risk and extent of soil disturbance and loss. The RPS advocates collaboration with primary industry, landowners and tÿngata whenua and promotes good soil management to ensure soil quality is maintained or enhanced. Regional and district plans will manage any effects on soils and manage location of developments on high class soils.
Subsidence: The Waikato region contains about 100 000 hectares of peat - about half of New Zealand’s peat land resource. Of the total area, 80% has been artificially drained for agriculture. Drainage and cultivation allows these soils to be farmed, but this results in subsidence (the gradual lowering of the lands surface).
Subsidence can adversely affect infrastructure, increase the risks associated with flooding and rising sea levels, require ongoing drainage system upgrades, limit agricultural productivity, reduce ecosystem services provided by peat, threaten the sustainability of adjacent wetlands and contribute to green house gas emissions. As set out in the RPS, research will be undertaken to better understand the effects of land management on the rate of subsidence and the long-term impacts of this on the peat resource and associated wetland ecosystems. This will inform plan development and land management practices.
Contaminated land and soil contaminants: People, animals and the environment can be exposed to risk from contaminated land in a number of ways, including direct contact with contaminated soil, swallowing food or water from contaminated environments and breathing gases or contaminated dust. As well as endangering health, these substances can limit the current and future uses of land and reduce land value. Therefore, areas of contaminated land will be identified and assessed - particularly prior to any development.
The RPS outlines the need to ensure contaminants in soils are minimised and do not limit the uses of the soil resource. For key soil contaminants including cadmium, fluorine and zinc, Waikato Regional Council will consider adopting risk-based guidelines and establish a process to determine discharge limits. It will work with industry and other stakeholders to identify, and incorporate into land management practices, actions to reduce the rate of accumulation of key soil contaminants.
Reece Hill, Senior Scientist for Science and Strategy (Land and Soil).
Justin Wyatt, Scientist for Science and Strategy (Land and Soil).
Bruce Peploe, Division Manager at Integrated Catchment Management (Business Process).
Alan Campbell, Land Management Advisory Services team Leader for Integrated Catchment Management (Land Management and Advisory Services).
Liz Tupuhi, Team Leader for Science and Strategy (Land and Soil).
“Soils are extremely important. They underpin our primary production-based economy and, through the way in which they are used and managed, have a critical role to play in addressing water quality issues in the region. We will continue to work with others toward maintaining and enhancing the health and function of our region’s soils. This will reduce the risks of, or associated with, soil loss, degradation, or contamination. It will also help avoid decline in the availability of our most productive and versatile ‘high class’ soils and ensure that existing and future soil uses are retained.” Haydon Jones, Land and Soil Scientist, WRC.