Nut IQ

For Higher Quality and Yields in Regional Hazelnut Cultivation

Hazelnut cultivation is gaining importance in Germany and offers potential for increased regional production. At the same time, losses in quality and yield pose challenges for growers. Hollow nuts, fungal infestations, brown spot disease, or premature fruit drop can significantly impair the quality and marketability of the harvest. Added to this are stress factors such as drought. However, there is currently a lack of site-specific knowledge regarding targeted nutrient supply for German growing conditions, as well as practical recommendations derived from this knowledge.

This is exactly where the Nuss IQ project comes in. The project is investigating how targeted foliar applications of zinc, boron, and silicon can help improve nut quality, reduce yield losses, and increase the plants’ resilience to stress.

Goals and approach

Zinc and boron play an important role in fruit development and kernel formation, but have rarely been used in a targeted manner in German hazelnut cultivation to date. This project therefore investigates the impact of these two micronutrients on quality and yield, as well as the optimal timing for their application.

Another area of focus is silicon. It can increase plants’ resistance to stress factors such as drought. Its effectiveness as a foliar fertilizer for hazelnuts has not yet been studied. Nuss IQ is conducting the first systematic evaluation of its use under field conditions in Germany.

To this end, field trials are being conducted over several growing seasons at three commercial farms in Hesse and Thuringia. Different application rates and timing for zinc, boron, and silicon are being compared. Soil and leaf analyses, as well as yield and quality data, show how these measures affect the plants and the harvested nuts. Monitoring the microclimate helps to relate the results to different site conditions.

In addition, a greenhouse experiment is being conducted to study hazelnut plants under controlled drought stress. This allows the effect of micronutrients to be assessed independently of field weather conditions. An economic evaluation of the measures will also show which approaches are not only beneficial from a crop production perspective but also economically viable for the farms.

The goal is to provide practical, site-specific recommendations that help hazelnut growers improve quality and yield and make their orchards more resilient to changing environmental conditions.

Collaboration Between Research, Consulting, and Practice

Nuss IQ is coordinated by the University of Kassel. It plans the field trials and evaluates the results. Justus Liebig University Giessen is responsible for the supplementary greenhouse trial and conducts key analyses of soil and plant samples.

The Thuringian State Office for Agriculture and Rural Areas supports the participating farms in Thuringia and contributes to the design of experiments and the evaluation of results. The three participating farms are directly involved in setting up and conducting the experiments, as well as in evaluating the results. The Hessian State Office for Agriculture is involved primarily in an advisory capacity and also provides support for knowledge transfer.

The exchange between research, extension, and agricultural practice is a central component of the project. Findings and experiences from Nuss IQ are shared with the agricultural community through field days, networks, extension services, professional publications, and the communication channels of the participating institutions, among other means.