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The Dutch NBS site is located in the north of the Netherlands in a UNESCO World Heritage site with special natural values and an important role in maintaining the hydrological balance of the region. Unfortunately, intensive agriculture in the region, primarily potato production (also cereals, horticulture crops and fodder), has also caused the depletion of soil fertility and reduced agricultural productivity. Farmers are looking for innovative NBS solutions to restore this lost productivity, as well as enhance the resilience and efficiency of their farms. In addition, the provincial government has a strong interest in implementing NBS innovations in line with their policies to encourage environmentally friendly, sustainable and resilient production systems.

Trans4num is testing the use of more natural approaches to crop nutrient management in three contrasting farming systems in the region:

  • An organic farming system with potatoes, wheat and carrots. Possible nutrient sources include grass-clover mixtures and lucerne etc., both for mulching and silage;
  • A conventional farming system with wheat in rotation, and;
  • A regenerative arable organic farming system with potatoes in rotation.

All field trials will be conducted on the SPNA Ebelsheerd and Kollumerwaard experimental farms. The SPNA researchers will collaborate with farmer groups at the study sites to design and test the NBS innovations and disseminate the results. Comprehensive soil and crop data will be collected from both sites for evidence-based decision-making.


SPNA Ebelsheerd

SPNA Ebelsheerd is located on heavy clay soils in a cereal-growing region. The experimental farm Ebelsheerd has both organic and conventional fields on a total area of 112 ha. The conventional crops grown are winter wheat, winter barley, rapeseed, onions, sugarbeet and lucerne. The organic crops grown are spring wheat, pumpkins and string beans. The NBS solutions will be trialled on 3 ha land.

SPNA Kollumerwaard

SPNA Kollumerwaard is located on reclaimed clay soils in a region growing mainly seed potatoes. The experimental farm also has both organic and conventional fields. The conventional crops grown are seed potatoes, sugarbeet, wheat and barley, and the organic crops are seed potatoes, carrots, oats, grass-clover mixtures, wheat and pumpkins. The NBS solutions will be trialled on 20 ha.

Cover crops in rotation with seed potatoes

Farmers in the north of the Netherlands are increasingly interested in cover crops to improve the production of high-quality seed potatoes. Cover crops have several benefits issues, including fulfilling the Common Agricultural Policy regulations, buffering uncertainties in the supply of fertilisers and improving soil quality. Farmers have their own preferences regarding which cover crops to sow but need more information on when best to destroy and incorporate them into the soil to optimise the availability of nutrients for the following potatoes. SPNA will research the availability of soil nutrients when the cover crop is destroyed at different times before sowing the seed potatoes.

This work will also include monitoring aphid populations since there is evidence to suggest different cover crops and other soil ameliorations can reduce aphid numbers and thereby enhance the efficiency of soil nutrient use.

Grass-clover mixtures in rotation with organic winter wheat

The heavy clay soils at SPNA Ebelsheerd are ideal for growing winter wheat. Organic winter wheat is mainly fertilised with animal manure; however, there are shortages of manure in the region and farmers are looking for alternatives. SPNA is therefore researching the use of grass-clover mixtures grown in rotation.

Lucerne and grass-clover pellets for fertilising winter wheat

Wheat production in the Netherlands is typically very intensive, with large inputs of mineral nitrogen fertilisers. Trials at SPNA Ebelsheerd will test the use of lucerne and grass-clover pellets (a form of biofertiliser) as an innovative alternative to the conventional use of mineral fertilisers. Comparison of the mineral and biofertilisers will include investigation of the impact upon both short- and longer-term soil nutrient status and crop yield and quality.



Henk Westerhof


Prof. Dr. Coen Ritsema