Sustainable subsurface

Nitrate sensor: measuring soil and surface water quality

In cooperation with

Wageningen University & Research (WUR)

Monitoring the quality of agricultural land and surface water is increasingly done with sensors. But current measurements are not very accurate and take time. We are developing optical sensors that are affordable and easy to use. They also provide very precise measurements in real time. This makes it easy to determine and monitor nitrate concentrations and their sources.

Healthy drinking water and fertile soil

Fertilisers enrich soil with nutrients such as phosphate and nitrate. These minerals are required for crop growth, but too much causes problems. The substances can leach into ground and surface water, putting the quality of our drinking water at risk. If fertiliser concentrations are likely to exceed threshold levels, stakeholders such as water boards, provinces, and water treatment plants need to know as soon as possible.

A successful prototype

We have developed a prototype nitrate sensor in close collaboration with Wageningen University & Research (WUR) and several companies. Together, we combined our in-depth knowledge of technology, agriculture, water management, and entrepreneurship. The initial test on farmland was successful. Now we want to partner with companies interested in developing the sensor for different types of soil and surface water.

Expansion of the existing monitoring network

In the early 1990s, a national monitoring network known as the Dutch Minerals Policy Monitoring Programme LMM was established to monitor the effects of the fertiliser policy adopted in the Netherlands. Several hundred agricultural companies are taking part. WUR and the Dutch National Institute for Public Health and the Environment (RIVM) gather the data and monitor water quality.

Once our sensor is on the market, it will be a huge expansion of the monitoring network. The data will no longer be sent to a lab for analysis because the optical measurements will be recorded in real time in a permanent nationwide system. The data will therefore be available immediately.

Optical measurement

The sensor is based on glass fibre technology. We use light to measure nitrate concentrations in water and soil. In the near future, we want to expand the application to other substances such as ammonium. Once this has been achieved, it will be possible to implement larger scale monitoring that assesses factors such as nitrogen deposition in Natura 2000 nature protection areas.

Mass transition to optical measurement will enable faster and more effective measures to ensure fertile soil and healthy drinking water. In addition, it helps to optimise the use of agricultural fertilisers. This ensures better growth of crops and saves on resources.


We are keen to talk to companies interested in further developing the sensor, adapting it for use with other substances, and bringing it to market. Are you interested? Let us know and get in touch with Rolph Segers.

Get inspired

3 resultaten, getoond 1 t/m 3

Making the subsurface sustainable


Within TNO, the Geological Survey of the Netherlands is organised as a knowledge centre of the subsurface.

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