Federated Farmers: Soil quality is crucial Landcare NZ

Good soils are at the heart of agricultural enterprise

How good are New Zealand soils?

"They're a bit like people really, they have their good points and their bad points," says Landcare Research soil scientist Allan Hewitt.

Overall, they're a mixed bunch, he said.

This is something early settlers discovered the hard way.

When settlers saw the large trees in the landscape they assumed that "big trees meant fertile soil" - a rule of thumb that applied in Europe. But when they started planting crops and developing pasture, that principle started to crumble and the need for wise management of soils to support productive agriculture became clear.

"Soils are a crucial non-renewable resource for our future," Mr Hewitt said.

Soil provides a range of invisible "services" that support plant growth and the environment - these include water storage, nitrate filtering, phosphorus filtering, aeration, and climate change regulation.

Mr Hewitt has developed a new method to assess the quality of soils to help land managers and decision-makers get the best out of the country's soils.

It was recently published in the global journal of soil science - Geoderma.

The new method estimates and maps soil services - also referred to as its "natural capital" - relative to the requirements of a specific land use.

"We're looking at the value of soil by determining the number of services it provides and relating that to the needs of a specific land use," he said.

"New Zealand's highly productive soils are very limited and there is strong competition between land uses. Soil natural capital is emerging as a useful concept for informing environmental and land use decisions."

Mr Hewitt said soil was an essential natural asset that needed to be preserved and the Food and Agricultural Organisation of the United Nations (FAO) agrees.

2015 has been declared the International Year of Soils in a bid to raise the world's appreciation of the importance of soil.

Here is the web address of the journal paper -- Soil natural capital quantification by the stock adequacy method: www.researchgate.net/publication/268821451-Soil-natural-capital-quantification-by-the-stock-adequacy-method

Background:

Landcare Research is a Crown research institute focused on environmental science.

A key part of our research looks at the complex inter-relationships that control the response of soils and landscapes to climatic and human-induced pressures, evaluating current risk, and offering sustainable land use and natural resource allocation options.

* More on our soil work:

/www.landcareresearch.co.nz/science/soils-and-landscapes