Adapting to salty conditions in the Netherlands : A joint report on activities from the ‘Dealing with Salinization’ project (2023-2024)

Summary

Salinization, characterised by the accumulation of excessive salts, poses a significant threat to global food security. Arable land affected by salinization continues to expand. These developments are also taking place in the Netherlands. Recognizing the urgency of addressing this challenge, various strategies can be explored for adapting to a saline environment. Within this context, the KB-34 “Dealing with Salinization” project dives into salinity adaptation strategies with a two-year initiative of greenhouse experiments and desk studies aimed at understanding the effects of salinity on the plant-water-soil nexus. Results from the project are presented in this joint condensed report of activities. - Chapter 1 introduces the concept of salinization in the Netherlands which is linked to rising seawater levels and land subsidence. Coastal regions of the Netherlands in the Wadden islands, Northern and South-Western part of the Netherlands are especially vulnerable to salinization. Impact of salinization on agriculture is devastating reducing crop yield, degrading soils, impacting income and generating unplanned costs to manage salt-affected areas. Because of this, associated economic losses due to salinization in the Netherlands may reach up to €600 million annually. - Crop experiments in semi-controlled saline conditions are reviewed in Chapter 2. Broccoli, potato and wheat showed varied yield and quality response under saline conditions. combining the use of salt tolerant varieties with the application of organic and inorganic soil amendments has potential to mitigate the impact of salinity and boost crop quality and/ or yield under salt stressed conditions. The salt tolerant variety of potato had significantly better yield and quality under saline conditions. Application of seaweed extract and zeolite only slightly improved tuber yield under these conditions and did not close the yield gap caused by salinization. - Chapter 3 goes more in-depth on the interactions between soil salinity, soil moisture and application of soil amendments in the two years plant experiments. Zeolite application improved water retention and moderated the effects of salt stress on soil moisture. Additionally, the salt tolerant potato cultivar outperformed sensitive cultivar in maintaining soil moisture stability and reducing salinity variability in the soil pots. These findings highlight the potential of integrating soil amendments into sustainable water and salinity management strategies. - The cost-benefit analyses of chapter 4 highlights that the seaweed-based biostimulant offer the most consistent financial returns under saline stress, particularly for the salt-tolerant potato variety. Zeolite, despite improving yields, often fail to justify their high costs. These findings provide critical insights into the financial trade-offs faced by farmers, informing decisions about adopting soil amendments as part of salinity management strategies - Upscaling of salinization strategies to landscape, regional and (inter)national scale is important and discussed in chapter 5. The butterfly framework is used to systematically analyse key factors needed of upscaling. Furthermore, we discussed the experiences on upscaling salinity in international context, where a shift from short term field level agricultural improvement-oriented strategies addressing salinity, towards long term management at landscape level is required. Reflection on the situation in the Netherlands, indicate recommendations to explore upscaling along the same lines such as making linkages between field scale and short-term measures, and landscape, regional and (inter)national scale level and long-term measures. - Land-use transitions that balance ecological, economic, and societal objectives is explored in Chapter 6. Salinized areas may adopt solutions, such as saline agriculture or aquaculture, which provide ecosystem services like biodiversity conservation, carbon sequestration, nitrogen cycling and flood protection. Aligning these transitions with societal goals and planetary boundaries ensures environmental resilience and long-term economic viability.