Nanomaterials in plant protection products and fertilisers
he use of nanomaterials in agriculture could, on the one hand, reduce cost and effort, increase efficiency and lead to more environmentally sound applications. On the other hand, it might also have a negative effect on microorganisms in the soil. This is concluded by the authors of a review article written within the scope of the National Research Programme "Opportunities and Risks of Nanomaterials" (NRP 64).
Although no plant protection products or fertilisers containing nanomaterials are available on the market as yet, nanomaterials are becoming an increasingly important issue in agriculture, particularly as additives or agents in fertilisers or plant protection products: The number of scientific publications and patents on nanomaterials in this area has increased exponentially since the turn of the millennium, according to a review article recently published by researchers from the Agroscope Reckenholz-Tänikon Research Station and the Federal Office for Agriculture (*). With around 70 articles published until now, it is still possible for researchers to gain an overview of the topic. The USA and Germany are leading the field with regard to patents, but most of the scientific articles have been written in Asian countries.
Often outside the traditional nano range
Approximately 40 percent of the publications deal with carbon-based nanomaterials, followed by titanium dioxide, silver, silicagel and aluminium. Nanomaterials can be integrated into formulations in different forms and states - from solid particles through to polymers and emulsions. It is noticeable that the material development is often based on natural and degradable basic substances. The nanomaterials used are often larger than 100 nanometres and therefore by definition lie outside the classical nano range. In new plant protection products, in particular, the nanomaterials often serve as an additive that helps to release the agent in a controlled manner.
1000-fold higher flux into soils
The potential improvement of plant protection products and fertilisers through nanomaterials is offset by their significantly higher flux into soils if nanomaterials are used. Experts currently predict that this rate could be as much as 1000 times higher than the load released from the atmosphere. Hence, soil organisms and crops would also be more exposed to these substances.
Companies in Switzerland are already required to declare any nanomaterials contained in new plant protection products that they wish to register. However, international principles of nano-specific risk assessment are still at the development stage. As part of the National Research Programme "Opportunities and Risks of Nanomaterials" (NRP 64), the project NANOMICROPS (Effects of NANOparticles on beneficial soil MIcrobes and CROPS) is contributing to these efforts by developing ecotoxicological test systems for soil microorganisms and crops as well as making available analytical methods for quantifying nanomaterials in agriculturally significant environmental compartments such as soil and water.