Science Centres: Pacific Rim

Soil erosion and the conseqeunt land degradation are serious problems around the world. NIWA is part of an international team developing novel techniques to help better inform land management in vulnerable areas.

The team we are part of involves 13 countries around the world including Chile, China, and Vietnam. We have developed a new robust forensic method for accurately identifying where eroded soil has come from.

The method developed by NIWA uses compound-specific stable isotopic analysis (CSIA) to identify the origin of soil in a sediment sample. When CSIA is combined with a second set of techniques – fallout radionuclide (FRN) – it can provide an assessment of exactly how much eroding soil has come from different sources.

Why is soil erosion so important?

Soil erosion is a natural processes but human activities such as deforestation, overgrazing, changes in land use, non-sustainable farming practices, and global climate change, can accelerate soil erosion. This often leads to landscapes become degraded, soil fertility, crop productivity, and water quality suffering, and increased sedimentation of lakes, reservoirs and floodplains.

If we can identify precisely the main sediment sources in a watershed, we can then identify the sites with critical soil erosion problems, and pinpoint where soil conservation measures will result in the biggest improvements in soil management and sustainable food supply.

An example – Vietnam

In Vietnam problems are arising because of a growing population, climate variability and change, and economic growth coupled with changing diet. Rice crops are being replaced with maize, and this agricultural intensification is leading to land degradation, especially in areas with steep slopes and high rainfall.

But where are the real hot spots of critical land degradation? Is it the maize cultivation, or is it in fact the homesteads,  the cassava, the timber wood plantation, or the bamboo forest? The CSIA technique coupled with FRNs can answer such questions.

A major output of this research will be decision-support tools for implementing precision conservation and contributing to sustainable land management.

This research is funded by the Joint Food and Agriculture Organisation (FAO)/International Atomic Energy Agency (IAEA) Division of Nuclear Techniques in Food and Agriculture. It aligns with NIWA research funded by the Foundation for Research, Science and Technology (FRST): ‘Land-use intensification: sustainable management of water quality and quantity’.

Contact: Max Gibbs